US2925156A

US2925156A - Drive control mechanism for prime mover with fluid actuated clutches

Info

Publication number: US2925156A
Application number: US705006A
Authority: US
Inventors: Arthur F Grant; Robert R King
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1957-12-24
Filing date: 1957-12-24
Publication date: 1960-02-16
Anticipated expiration: 1977-02-16

Description

Feb. 16, 1960 A. F. GRANT ETAL 2,925,156;

DRIVE CONTROL. MECHANISM FOR PRIME MOVER l WITH FLUID ACTUATED CLUTCHES Filed Dec. 24, 1957 6 Sheets-Sheet 1 CLUTCH .s2/P

7U CLUTCH y"T4/.Q SUPPLY ENG/NE ROOM CO/VTRL SWT/01V mun/WAL za/vf PILOT HOUSE CO/VTPDL Feb. 16, 1960 A. F. GRANT ETAL 2,925,156

DRIVE CONTROL MEcHANIsM Foa PRIME MovER WITH FLUID ACTUATED cLuTcHEs Filed Dec. 24, 1957 6 Sheets-Sheet 2 INVENTORS A. F. GRANT ET AL DRIVE CONTROL MECHANISM FOR PRIME MOVER Feb. 16, 1960 WITH FLUID ACTUATED cLUTcx-IES 6 Sheets-Sheet 3 Filed Dec. 24, 1957 Mm o e 1.... E M Z fw w um 5 W my E uw.. 5 N A F U ,al E E C M ../v ma Amr 6 v/w y ,Mm wam w M 6 W w E W L 5 UAA p AE MW Mp6 c MN 5 Ma www w A my m .4m m .f MR 3N 7H M E 0 M 2 M mlmw Y T Y Umlmm m w w m Sum mlw nog E .G o mi wm E M. 0 W m H mw ,NEM RP 5X Ew Ul 0 an m e v m w m .w m. w o

maaar/nm TIME- Ml SECGNDS Feb. 16, 1960 A. F. GRANT ET AL 2,925,156

DRIVE CONTROL MECHANISM FOR PRIME MOVER WITH FLUID ACTUATED CLUTCHES 6 Sheets-Sheet 4 Filed Dc. 24, 1957 SUPPLY HS TEEN cL urcf/ INVENTORS A TUR/VE Y Feb. 16, 1960 A. F. GRNT ETAL DRIVE CONTROL MECHANISM FOR PRME MOVER Filed Dec. 24, 1957 WITH FLUID ACTUATED CLUTCHES 6 Sheets-Sheet 5 Feb. 16, 1960 A. F. GRAN-r Erm.

DRIVE CONTROL MECHANISM FOR PRIME MOVER WITH FLUID ACTUATED CLUTCHES Filed Dec. 24, 1957 6 Sheets-Sheet 6 Em bkb NU QN ,SNT

(JLMR INVENToRs @zaga/z Gao/)ff Blf/70d??? nited States aten 4 2,925,156 DRIVE CONTROL MECHANISM FOR PRIME MovER wIrH FLUID AcrUArnn cLUreHEs F, Grant, Cleveland, and Robert R. King, Lakewood, Ohio; said Grant `assgnor to General Motors Corporation, Detroit, Mich., a corporation of 'Delaware' Appiieaton December 24, 1957, Serial No. 705,006

This invention relatestocontrol apparatus of the tiuid pressure type for selectively controlling the speed of a unidirectional prime mover and the selective operation of clutches for controlling the speed and direction of an output member and has particular application to maneuvering control systems for marine propulsion drives.

Where a prime mover on a ship is operative in one direction only, it is customary to employ either a reversible electrical drive or forward and reverse clutches for selectively controlling the rotational direction of the propeller and hence the propulsion of the ship in either the forward or the astern directions. Prior to the instant invention, the operating characteristics of reversible electrical drives have generally been deemed to be much superior to those of reversible clutch drives, providing a responsiveness, a fneness, and an adaptability of control not considered possible with a clutch drive. However, such electrical drives andthe controls therefor are relatively complex and expensive. Hence, reversible clutch drives have been utilized `quite extensively in those applications where a high degree of neness and responsiveness` of control have not been required. VWith such clutch drives it is of course necessary to match the starting and running torque characteristics of the individual clutches with the speed and torque characteristics of the prime mover.

To reverse the direction of operation of the propeller with a reversing clutch drive, it is only necessary to disengage the one clutch and to subsequently engage the other. However, to minimize the power dissipation or work imposed on theoncoming clutch and thereby clutch Wear and to prevent damage to the clutches on other parts of the power transmitting mechanism upon clutch engagement, it has generally been desirable that the prime mover and the propeller rst be brought to and maintained at a low speed such as the idling speed of the prime mover before disengagement of the operating clutch and energization of the other clutch for engagement. To minimize' the possibility of stalling the engine during such low engine speed clutch engagement the engine idle fuel setting has necessarily been established at a rate higher than that which would otherwise have been required thus reducing overall operating eiciency of the power plant or provision has been made in the control mechanism for advancing the engine fuel setting slightly above its idle rate during the clutch engaging period.

The invention contemplates the provision of a simple, rugged, foolproof and relatively inexpensive marine drive and control system for a prime mover having speed setting means and ahead and astern driving clutches and including an improved single-lever maneuvering control mechanism interconnecting the speed setting means and clutches and adapted to provide controlled clutch engage ment comparable in smoothness and controllability to an electrical drive' and further to provide a controlled increase-in the speed setting of the prime mover and in the torque transmitting capacity of the engaged clutch after 2,925,156 Patented Feb. te, i960 initial full engagement of either clutch in response to manual movement of the manuvering control lever between a neutral zone and full speed ahead and astern contro;ling positions.

The combined means by which the foregoing objectives are accomplished, together with other novel. features and advantages of the invention, will become more apparent from the following detailed description of several embodiments thereof having reference to the accompanying drawings in which:

Figures l and la are diagrammatic views, partly in section and partly in outline, of complementary portions of an engine speed and clutch engagement control mechanism embodying the invention;

Figure 2 is a` graph showing the interrelationship between engine and output shaft speed and clutch ination pressure for the embodiment of the invention shown in Figures l and la;Y

Figure 3 is a graph showing the operating cycle of the form of the invention of Figures l and la in a full ahead and full asternreversal;

Figure 4 is a graph similar to Figure 3 showing a full' astern to full ahead reversal; and

Figures 5 to 8 are diagrammatic views showing modi'- fied forms of the invention.

DESCRIPTIONQFIGURE 1e Referring `more particularly to Figure la, a two-way reverse clutch is indicated generally at 10 and includes an ahead coupling 11 andan astern coupling 12; The two coupling units are selectively energizable to drivingly interconnect a unidirectional engine 14 to a propeller drive shaft loof a ship to provide either forward or reverse drive, respectively, through a suitable reverseand-reduction gear mechanism 18. The coupling units are independently operable by fluid pressure and in a first range of operation are adapted to provide controllable slip of the propeller shaft relative to the driving engine, the speed of the output shaft being substantially proportional to the actuating pressure applied thereto up to a given pressure `at which either coupling is normally fully engaged under engine idle speed and load conditions. Further increase in the actuating pressure supplied to either coupling above such a given pressure serves to further increase the speed and torque capacity of the coupling unit. g

The two-way reverse clutch 10 includes a driving input assembly common to both the forward and reverse couplings. This driving assembly comprises an engine driven stub shaft 20, a driving spider or disk 21, an annular drive adapter 22, and a driving drum or housing including annular end plates 23, 24 and intermediate members 25, 26, all of' which are secured together by suitable means. The intermediate housing members Z5 and 26 have outer cylindrical portionsextending axially from the `end plates 23 and 24 and adjacent end portions which `extend radially inwardly to provide ltwo flanges in spaced parallel relation to the end plates 23 and 24. The

members

23, 24 and 25, 26 thus define two annular recesses for mounting the

coupling units

11 and 12.

The

coupling units

11 and 12 each includes two axially spaced annular clutch plates 28, 29 and 310, 31, respectively, which are externally splined to the housing members 25 and 26, respectively. These clutch plates carry shoes of suitable rictional material and are adapted to frictionally engage clutch plates 32 and 33, respectively, which are sandwiched therebetween. The clutch plate 32 is internally splined to an ahead drive hub 34 and the clutch plate 33 is similarly splined to a reverse drive hub 35. The ahead drive hub 34 is drivingly connected to a hollow input drive shaft 36 of the reverse-and-reduction gear unit 18. The reverse drive hub 35 is journaled on the s haft 36 by spaced antifriction bearings 37, 38 and is drivingly connectable to the input drive shaft 36 and the propeller shaft 16 bya conventional reversing-andreduction gear mechanism within the gear unit 18, a bevel gear of a differential type reversing gear being partially shown at 39. The drive plates 28, 29 and 30, 31 are adapted to be biased into frictional driving engagement with the output drive plates 32 and 33 by the selective inflation of two annular tubes 40 and 41 carried by the drive housing end plates 23 and 24. The axial expansion of the tubes 40 and 41 is transmitted to the several clutch plates through intermediate heat-insulating plates 42 and 43. To insure disengagement of the several clutch plates whenever the tubes 40 and 41 are vented to atmosphere, a plurality of radially and equi-angularlv spaced springs 44 are adapted through a plurality of radially extending iingers or spokes 45 to bias the menibers 42 and 43 out of drive maintaining engagement with the adjacent clutch plates.

The clutch plates 42 and 43 are radially slotted to provide a plurality of radial ribs 42' and 43' which are adapted to thrustablv engage the adjacent surface of the

drive plates

2,9 and 31 and define a plurality of radially extending passages therebetween. The inwardlv extending flange portions of the housing members 25 and 26 are similarlv slotted to provide radial passage-defining ribs 25 and 26 engaging the adjacent surfaces of the drive plates 29 and 30, The drive plates 32 and 33 are also provided with a plurality of radially extending cored passages 32' and 33'. The several passages thus defined intermediate and within the several clutch plate elements open on radially extending passages or ports in the cylindrical portion of the housing members 25 and 26 and upon rotation of the several clutch members these passages serve as radial impellers inducing7 the rapid flow of cooling air therethrough thus dissipating the heat generated during the clutch engaging process.

Fluid under pressure is supplied to and discharged from the clutch actuating tubes 40 and 41 by way of two iiexible air tubes 46 and 47, respectively, which are in turn connected to air supply passages 48 and 49 provided in an air supply tube or shaft 50. The air supply shaft 50 is journaled in and proiects from the ends of the hollow input drive shaft 36 yof the gear mechanism. The engine end of the air supply tube 50 is drivingly connected to and supported by the input driving assembly of the clutch unit 10. a plate 51 carried bv the driving spider 21 and the ange end of the stub shaft 20 being universally connected to the adjacent end of the air tube 50 as indicated at 52. The passages 48 and 49 terminate adjacent the opposite end of the air tube in two axially spaced ports 48 and 49', respectively. These ports register with annular grooves 54 and 55. respectively, which are formed in a fluid seal member 56 journaled on the end of the air tube shaft. The annular grooves 54 and 55 are in turn connected to two inflation

pressure supply pipes

101 and 102, respectively.

The engine 14 is provided with an engine driven centrifugal governor 57 of a conventional type having a speed setting shaft 58 rotatable therein with a lever arm 59 secured thereto. The speed setting shaft 58 is adapted upon rotation in a counterclockwise direction to increase the governor speed setting and conditions the governor to regulate the fuel supplied to the engine to maintain engine speed and power output in a well known manner in accordance with the speed setting established thereby. As shown, the speed shaft and the lever 59 are in their engine idle speed maintaining position. The end of the lever 59 distal from the shaft 58 is pivotally connected to one endof a link 60. The opposite end of the link 60 is pivotally connected intermediate the ends of an output lever 61 of a pressure operated motor or actuator device 62.

The actuator unit 62 is connected to one end of a pressure supply pipe 126 and is operable in accordance .4 with pressure supplied thereto to adjustl the speed setting of the governor. Variations in the pressure supplied to the actuator unit above a predetermined minimum eect the ieciprocation of a rod or plunger element 64 which is pivotally connected to the actuator output lever intermediate its connection to the link 60 and a stationary pivot 63 at one end of the output lever. Thus an increase in the pressure supplied to the actuator effects counterclockwise speed-increasing movement of the lever 61 about its stationary pivot 63. The pressure responsive move-V ment of the actuator lever 61 is limited between engine idle and maximum speed and load positions defined by stop screws 65 and 65', respectively. The governor speed adjusting linkage intermediate the governor and the spede adjusting actuator is biased in a fuel decreasing direction in opposition to the pressure applied to the actuator unit by suitable spring means, not shown, associated with either the governor or the speed adjusting actuator.

DESCRIPTION-FIGURE l1 In the form of the invention shown in Figure 1, two control stands 66 and 67 are provided for controlling the operation of the two-way reverse clutch and the speed setting of the engine governor. For the purpose of illustration, the control stand 66 is designated as a pilot house control station and the control stand 67 is designated as an engine room control station. As the two control stands are identical in structure and function, corresponding elements of the two stands are hereinafter designated by the same reference numeral, the elements of the engine room stand being differentiated only by the use of a prime The selection of the controlling station is accomplished by the selective operation of a transfer valve 68 including a valve member 68' shiftable between either of two. control positions in which the transfer valve is effective to connect the selected control station to a main pressure supply pipe69 and to deliver pressure control signals therefrom to other elements of the overall control system. The transfer valve member 68 may be selectively shifted between. its two control positions by any suitable manual control means, not shown, from a location adjacent either control station. In the position shown, a passage or port a provided in the transfer valve member 68 connects the main pressure supply pipe 69 to pipe 70 for supplying pressure fluid tothe several control elements of the control stand 66 thus rendering the stand 66 effective to control the operation of the reverse clutch mechanism and of the governor speed adjusting actuator.

A single manually operable maneuvering control lever 71 is secured to a control shaft 72 which is rotatably` mounted in the control stand 66 for movement between a neutral position or zone and full speed ahead and astern controlling positions to either side of the neutral position, such positions of the control lever being designated by suitable legends in Figure 1. Two cams 73 and 74 are carried by the shaft 72 and selectively actuate an ahead shift control valve 75, an astern shift control valve 76, and a variable pressure regulator valve 77 in accordance with the direction and degree of movement of the control lever 71 from its neutral Zone.

The cam 73 is engaged by two diametrically opposed cam-following valve members 78 and 79 of the two shift control valves 75 and 76. The valve members 78 and 79 normally engage a base circle on the cam 73 when the control lever 71 is in its neutral zone. When in such engagement with the base circle, the valve members 78 and 79 are operative to connect both an ahead shift control pipe 80 and an astern shift control pipe 81 to an exhaust header 82. Operation of the control lever 71 beyond its neutral zone in either-direction causes a single lobe A formed on the cam 73 to shift either the valve member 78 or 79, in accordance with the direction of lever movement, to connect either the ahead or astern 54

Shift control pipe

80 or 8,1, respectively, to the pressure supply pipe The valve member 78 or 79 not shifted by the cam lobe upon such lever movementcontinues to engage the base circle of the cam 73 and thus continues to exhaust the shift control pipe associated therewith.

The variable pressure regulator valve 77 includes a valve member 83 which is adapted` to follow the cam 74. The contour of the cam member 74 is such that when the control lever 71 is in its neutral zone the valve member 83 is operable to connect a clutch inflation and speed control pipe 84, to the exhaust header 82 of the control stand. Movement of the control lever through the indicated end of its neutral zonein an ahead direction causes a lobe B on the cam 74 to actuate the valve member 83 to a control position in which it is eiective to deliver an initial pressure signal to the pipe 84 which, it applied to the ahead clutch would be suilicient to equal the biasing action of the springs 44. Further movement of the control lever 71 in the ahead direction between its neutral zone and an intermediate lever position, designated idle in Figure l, causes the cam operated valve member S3 to progressively increase the `pressure signal supplied to the pipe 34 up to a pressure which, if applied to the ahead clutch actuating tube 40, would normally be eiective to provide full lookup engagement at engine idle speed and load conditions. The lobe B `of cam 74 is so contoured that further movement of the control lever 71 through its idle position increases the pressure signal delivered to the pipe 84 by the pressure regulator valve to a value which, if applied to the engine governor speed adjusting actuator 62, would equal the biasing action of the spring means associated with the speed adjusting linkage intermediate the governor and actuator. Still further movement of the control lever between itsidle and full ahead positions is effective to progressively increase the pressure signal supplied to the pipe 84 to a maximum pressure which, if applied directly to the ahead clutch and engine speed actuator, would provide for maximum clutch running torque capacity and maximum engine speed. Movement of the control lever 71 between its neutral zone and its full astern position causes a second lobe C on the cam '74 to actuate the valve member 83 to supply corresponding pressure signals to the speed and clutch inflation control pipe 84.

In addition to the pressure supply passage a, the transfer valve member 68' is provided with passages b and c which, in the position shown, interconnect the pipes and 81, respectively, to pipes 85 and S6, respectively.

The pipes 85 and S6 are connected to opposite ends of a double-acting fluid motor 87 which is operable to control the operative position of a four-Way shift selector valve 88. The

pipes

85 and 86 are preferably each provided with a conventional flow control type valve indicated diagrammatically at 8S' and 86', respectively, consisting of an orifice restricting uid flow toward the motor 87 and permitting relatively unrestricted ow away from the motor. The transfer valve member 68 is also provided with a passage d which, in the position shown, interconnects the speed and inflation control pipe 84 to a pipe S9. The pipe 89 leads to a pilot operated pressure regulating relay valve 90. The pressure regulating valve 90 is adapted to interconnect a speed and inflation control pipe 91 to either the main pressure supply pipe 69 or an engine room exhaust header 92 and supplies an output pressure to the speed and ination control pipe 91 equal to the pilot signal imposed thereon. Thus when the control lever V71 is in its neutral zone, wherein the pressure regulator valve 77 is operable 'to -vent the pipe 84 to exhaust, the pressure regulating relay valve 90 is similarly operable to connect the pipe 91 to the exhaust header 92. Upon movement `of the control lever 71 from its neutral Azone in either direction, the pilot pressure imposed on the pressure regulating relay valve 90 causes the regulating relay 90 to supply the same pres sure to the speed and ination control pipe 91 from the main pressure supply.

The four-way selector valve 88 comprises a cylindrical housing or barrel 93 having a bore 94 extending axially therethrough. A valve member 95 is reciprocably mounted'within the bore 94 by a plurality of axially spaced O-ring seals 96 which are compressively interposed between and retained within the bore 94 by a plurality of annular port defining rings 97. An inlet port 98 opens on the bore 94 intermediate its ends and is connected to the speed and ination control line 91. Two outlet ports 99 and 100 open on the bore 94 in flanking relation to the inlet port 98. These outlet ports are connected to an ahead inflation control pipe 101 and an asterninflation control pipe 102, respectively, which are in turn connected to the annular ports 54 and 55, respectively, of the annular rotary seal member 56. The valve barrel 93 is further provided with two exhaust ports 193 and 104 which open on the bore 94 and are spaced axially outwardly of the outlet ports 99 and 100, respectively. These exhaust ports are connected to the engine room exhaust header 92.

The valve member 93 is provided with two axially spaced reduced diameter lands 105 and 106 which separate enlarged diameter land portions 107, 108 and 109 adapted to sealingly engage the port separating O-ring seals 96. A piston member 110 carried by the valve member 95 is reciprocably mounted within the cylinder S7 and defines two double acting expansible 4chambers 111 and 112 therein which `are connected to shift

control pipes

85 and 86. The valve member 95 is thus shiftable to an extreme left-hand position in response to fluid pressure applied to the expansible chamber 111 of the cylinder 87 through the shift control pipes Sii and 85, the chamber 112 being simultaneously vented to exhaust through pipes S1, 86 and the astern shift control valve 76. In this left-hand position the reduced diameter land 105 interconnects the pressure inlet port with the ahead ination outlet port 99 and the astern inflation tube is connected to exhaust by the reduced diameter land 106. Similarly, a shift controlling pressure signal applied to the expansible chamber 112, chamber 111 being vented to exhaust, is operable to shift the valve member to an extreme right-hand position wherein the reduced diameter land 105 serves to vent the ahead clutch and the reduced diameter land 106 interconnects the astern clutch inflation tube to the pressure inlet 98.

When the control lever 71 is in its neutral position, it will be noted that both the expansible chambers 111 and 112 will be vented to the exhaust header 82 through the shift control valve 75 and 76. When the chambers 111 and 112 are thus vented, the Valve member 95 is adapted to be centered to the position shown in Figure l by a centering spring assembly 113 mounted on the end of the valve barrel 93 opposite the actuator cylinder 87. ln this intermediate position, the lands 105 and 106 connect both the ahead and

astern inflation pipes

101 and 102 to the exhaust ports 103 and 104, respectively. The centering spring assembly includes a cylindrical casing 114 having two inwardly extending, axially spaced an nular shoulders 115 and 116. The shoulder 116 is in the form of a groove-mounted snap ring. rl`he shoulders 115 and 116 serve as abutment stops for two Washer members 117 and 118 which slidably embrace a reduced diameter land formed between two axially spaced shoulders 120 and 121 carried by the adjacent end of the valve member. A spring 122 is compressibly interposed between the washer members 117 and 118 and serves to center the valve member by axially aligning the abutment shoulders 115, 120 and 116, 121 of the casing 114 and valve member 95, respectively, in the absence of actuating pressure in either of the expansible chambers 111 and 112.

-In the `form of the invention shown in Figures l and la, the speed control pipe 126 is provided with a ow f t :warmesvvv control valve 126 diagrammatically shown to be of the type having an orifice` limiting the flow of actuating fluid to the `speed actuator 62'and a check valve permitting unrestricted flow therefrom. The speed control pipe 126 is alternately connectable through a two-way lcheck valve 123 to either the inflation pressure supply pipe 101 or 102.v The two-way check V Valve 123 comprises a cylindrical casing closedat both ends and reciprocably mounting a check valve member 125. Two branch,

pipes

101 and 102 connect the

clutch inflation pipes

101 and 102, respectively, to opposite ends of a check valve casing and the pipe 126is connected thereto intermediate its ends. The valve member 125 is shiftable in response to the pressure supplied to either of the

pipes

101 or 102, the other line being vented to exhaust, to permit the flow of the supplied pressurized fluid to the speed adjusting actuator 62.

DESCRIPTION-FGURES 2 4 Operations of embodiment of Figures I and la The operating characteristics of the form of the invention of Figures 1 and la are best shown by the

several graphs of'MFigures

2, 3 and 4 having reference to a specific application thereof to a tug having a diesel engine prime mover rated at 1000 S.H.P at 750 r.p.rn.

InFigure 2, curve I indicates the interrelationship between the propeller speed, in direct proportion to the engine speed, and the pressure signal supplied to the inflation and speed control pipe 84 by the control stand pressure regulator 77 upon movement of the control lever between its neutral and either its full ahead or astern positions. Curve II represents the minimum clutch inflation pressure required to maintain a given output shaft speed when the tug is running free, without tow, and thus represents a minimum torque condition. Curve Ill represents the minimum clutch inflation pressure required to maintain a given output shaft speed when the tug is driving against a dock thus simulating a torque condition corresponding to that required to initiate a tow. Above the clutch slip range curves II and Ill further define the inflation pressures at which the speed of the output shaft of the clutch corresponds to that of the clutch input shaft, the creep therebetween being less than one revolution for thirty minutes of operation. As indicated, the pressure differential between curves l and Il or III represents additional available clutch torque capacity for acceleration of the tug and its tow. This excess torque capacity insures against any prolonged periods of clutch slippage under high speed and torque conditions. f

Assuming the engine to be operating at idle speed with the control lever 71 of the controlling station in its neutral position or zone, both the ahead and the astern clutches are de-energized since the shift selector valve member 95 is in its neutral position venting both inflation tubes 40 and 41 and the governor speed setting actuator 62 to exhaust. Initial movement of the control lever from its neutral Zone actuates one of the shift control valves 75 or 76 to supply actuating pressure to one end of the actuating cylinder 87 thereby causing the piston 110 to shift the selector valve member 95 to one of its two shift controlling positions in accordance with the direction of control lever movement. Such initial movement of the control lever also shifts the regulating valve member 83 to close the connection between the exhaust header 82 and the inflation and speed control pipe E4 and to provide an'initial supply of pressurized fluid of approximately three pounds per square inch to the latter pipe. As duplicated by the pressure regulating relay valve 90 and supplied to either of the clutch actuating tubes 40 or 41 through the shifted selector valve 8S, this initial pressure of three pounds issufficient to overcome the biasing action of the springs 44 and initiates frictional driving engagement between the several plates of the corresponding clutch unit thereby initiating rotation of the propellerl shaft. Further advancement of the control lever 71 in either its ahead or astern control slip ranges serves toincrease the actuating pressure supplied to the oncoming clutch thereby decreasing the slip and increasing the torque transmitted between the driving and driven members. Thus the speed of the propeller shaft may be effectively controlled by the operator-selected position of the control lever to hold the tug against a tidal or river current or to slowly and smoothly initiate propulsion of the tug and its tow. The actuating pressure supplied to the oncoming clutch will generally be effective to shift the two-way check valve 123 to supply such pressure to the speed controlv pipe 126. However, when the control lever is in either of its clutch slip zones, such supplied pressure will be ineffective to actuate an adjustment of the governor speed setting. Y

As the control 71 is advanced toward its idleV position,

the inflation pressure supplied by the regulator valve 77 approaches a value of approximately 10 pounds per square inch which is the inflation pressure required to" provide full engagement between the driving and driven members of the clutch unit under engine idle maximum torque conditions. Further movementof the( control lever into its vengine idle position causes the regulator valve 77 to increase the pressure supplied to the inflation and speed control line 84 to a value of approximately 121/2 p.s.i. When duplicated by the relay regulating valve and supplied through the shifted selector valve to either of the

inflation control lines

101 or 102 and therefrom through the two-way check valve 123 to the speed control line 126, this pressure is effective to counterbalance the spring means biasing the governor speed adjusting linkage to its idle position. Movement of the control lever between its idle and full speed ahead or astern positions varies the magnitude of the pressure signal supplied to the line 84 by the regulator 77 in proportion to the degree of movement of the control lever. Thus, for any given position of the control lever in either of its idle-to-full speed zones, a pressure signal is provided which provides a given torque capacity for the driving coupling and effectsA the adjustment of the governor speed setting to provide a given engine speed and thereby a given propeller shaft speed.

In actual practice, the operation of the control lever 71 will generally not be accomplished slowly and smoothly enough to increase the pressure signal and thereby prof peller speed as per curve I of Figure 2.

Normally the operator will actuate the control 71 almost instantaneously to a position corresponding to the desired propeller shaft speed. Assuming an almost instantaneous movement of the control lever 71 from its neutral control zone to a second position within its ahead engine speed controlling zone, such a movement of the lever causes the ahead shift control valve 75 to supply a pilot signal to the cylinder 87 thereby actuating the valve member to its ahead drive establishing position. Such lever movement also rapidly actuates the regulatorV valve member 83 to a position wherein it is effective to supply a pilot pressure signal corresponding to the second position ofthe lever 71, by way of example, 50 pounds per square inch. This pressure signal is applied to and duplicated by the pilot operated pressure regulating relay valve 90. The flow of the 'pressurized fluid emanating from the regulating relay valve 90 through the selector valve 88 to the ahead clutch actuating tube 40 and through the two-way check valve 123 to the governor speed actuator 62 is retarded or throttled by the orice of the ow control check valve 91'. The flow of the supplied actuating pressure to the governor lspeed actuator 62 is further retarded by the flow control valve 126'. It will thus be seen that the flow controlvalve 91' controls the ination of the clutches to provide relatively smooth progressive engagement under such Aoperating conditions and'cooper-l ates with the ow control valve 126 to retard advancerrr-entf of' the engine speedg governor` setting. during clutch t.

achieve'` a reversal of: propeller drive from full speed ahead to full speed astern, or vice versa,` within a period of ve seconds without undue; heating andV wear of the several clutch elements. In Figure 3 curve IV represents enginespeed per unit time and: curve VIE represents the speed andi direction of the propeller shaft` per unit time dringf such a high. speed` reversal. Curves V and` VII indicate corresponding engine and propeller speed` curves andthe minimum. time for effecting sucha high speed reversal with a comparable electric drive for` the same tug. In Figure 4 the engine speed curve IV is duplicated during/the full speed astern to full speed ahead reversal ofthe propeller shaft, the speed of which is indicated by thecurveVIII.. The broken line curve IX in this figure indicates the free wheeling of the propeller shaft which would occur upon complete disengagement of the astern driving clutch12 if engagement of the ahead clutch were not, almost immediately initiated to eiect a braking action ontheastern rotation of the propeller drive shaft system.

The. operation ofthe control system during such high speedi maneuvering reversals is outlined briefly below. Movement of. the control lever 71 from its full ahead position to `its full astern position vents the valve shift actuator` chamber 111 through the ahead shift control valve 75 to the exhaust header 82. Opening of the check valve of theow control valve assembly 85' permits this venting of the chamber 111 to be relatively unrestricted. However, the pilot pressure from the astern shift control valve` 76 is restricted in its applicationto the expansible chamber 112 by the orifice of the flow control valve 86.

Consequently, the centeringV spring assembly 113 initially actuates the valve member to its centered position, wherein it vents the ahead clutch and the governor speed adjusting actuator to the exhaust header 92, until the astern shift pilot pressure is sufficient in the expansible chamber 112 to shift thevalve member 95 to its astern. shift controlling position `wherein the land 106 interconnects the astern inilationand speed control pipe 102 to the regulated pressure supply of the relay valve 90. During the rapidI movement of the control lever 71 from its full ahead 'to-full astern positions the ination and speed controlling pilot signal emanating from the pressure regulator valve. 77 is reduced until the control lever passes through its neutral zone wherein the ination and speed control pilot line 84 are connected to the exhaust header S2 and is subsequently increased until it again reaches its full engine speed value. However, it should be noted that this pilot ination and speed controlling signal, as duplicated byv the relay valve 90, is not applied to the oncoming astern clutch until the initial centering of the shift selector valve 95 has first vented the ahead clutch ination tube and the governor speed actuator thereby substantially disengaging the ahead clutch and reducing the engine governor to its idle speed setting. This is best seen from curves VI, VIII and IX which show the propeller shaft speed curves VI and VIII tending to follow the free wheeling curve IX until the engine speed has been reduced substantially to its idle position.

By proper selection or adjustment of the orifice size of the ow control valve assembly 86', as the engine appraches `its idle speed the shift selector valve member Figures;L 3 t and 4, it is` V is` shifted; to; its asternw .controlling` position` thereby,-

initiating the il'owrofactuating pressure tothe oncoming` asternwclntch. This flow 0f pressurized fluid" tothe on.- coming` clutchiswof course restricted by the-How control valve assembly/w1 Hence, the astern clutch issmoothly and progressively. energized` throughout its clutchv slip rangel to initially,` brake the` ahead rotation of the propeller shaft; system` down to zero speed and then to` reverse and drive the propeller with increasing speed and torque. As the` astern clutch becomes effectively fully engaged at engine-idle speed, the increasing pressure is applied to,` thegovernor. speed actuator through the

twowaychecktvalve

12,3 and serves to progressively increasev the governor speed setting, up to its full speed and` power` maintaining position.

A reversal. from. full` speed astern to full speed aheadis similarly effected-by the embodiment of the invention; of Figures 1f and. la, as shown by the graph of Figure 4, and consequently need not be discussed in detail. However, it.- willybe noted` that the propeller shaft and engineKV speed curves `IV--and VIIIf coincide between the point at which the oncoming aheadY clutch` is fully engaged and the full` speed ahead condition.

From' the f oregoingdescription ofthe operation of the form of the invention of Figures 1 and 1a it will be` seen that the four-way-shift selector valve 88 provides a positive mechanical interlock preventing the simultaneous, supply ofV actuating. pressure to the actuating tubes of` both the ahead and astern` clutches and when utilized with the ow control valves S5 and 86 insures substantial disengagement of the oifgo'ing clutch before engage,- ment ofthe oncoming clutch is initiated. This latter feature, when., taken in conjunction. with the two-Way check valve 123, Aserves to provide a positive pneumatic interlock between, clutch inflation. and engine speed and` is effective to-reduce engine speed` during` reverse maneuvering operations thereby prevent-ing excessive heating of` the clutches. This interlockingarrangement also prevents stalling o'r overloading the engine during such reversing operations since theclutch torque capacity at any particular pressure setting within the clutch-slip, engine idleV range is insuflicientto stall the idling engine. After initial full clutch engagement, the available clutch torque` capacity at any particular pressure setting is: substantially greater than the available engine torque. It should also`V be notedl that since clutch ination pressure is used to control the governor actuator through the two-way check valve, this arrangement will automatically result in a reduction in engine speed in the event of a low clutch inflation pressure which might otherwise permit destructive clutch slippage.

DESCRIPTION-FIGURE 5 In the form of the invention of Figure 5, the drive intermediatethe engine and the propeller shaft, the engine governor speed adjusting mechanism, and the remote control stations, as well as` other component elements, are identical with those shown and described with reference to Figures 1 and la. Such components are therefore represented by the` same reference numerals in Figure 5 although being shown somewhat more diagrammatically.

In this form of the invention, the pilot pressure actuation of the four-way selector valve 88 by the control lever operation of the shift control valves 75 and 76 is positively interlocked by means of suitable clutch inflation pressure actuated relays 134)y and 131 to assure complete disengagement of one clutch before the other clutch is actuated to drivingly connect the propeller shaft to the engine. This positive interlocking o'f the` selector valve `shifting is utilized in place of the controlled time delay which is introduced by the ow control valves 85 and 86' of the first embodiment and momentarily maintains the selector valve in its neutral position during the reversal cycle.

The inflation pressure actuated relays and 131 are associated with and adapted to control the tlow of pres.-

surized fluid to the opposite ends of the shift selector valve actuating cylinder 87 through the

pipes

85 and 86, respectively. The valve members of these twov relays are normally spring biased to a position indicated by the broken lines e and f, respectively, to provide a through passage between the separate ends o'f the

pipes

85 and 86, respectively. -To assure complete disengagement of either the ahead or astern driving clutch before the other clutch is energized to pick up torque, the pressure actuating means of the ahead shift controlling relay 130 is connected to the astern speed and inaton control pipe 102` by a pipe 102' and the pressure actuating means of the astern shift control relay 131 is similarly connected to the ahead ination and speed control pipe 101 by the pipe 101'. Hence, when an inflation and speed control- /ling pressure is supplied to the pipe 101 sufficient to initiate engagement of the ahead clutch, this signal is applied to the astern shift control relay 131 and is operative to actuate the valve member thereof to a second co'ntrol position indicated by the broken line f to connect the portionof the pipe 86 intermediate the actuator cylinder 87 and the relay to the engine room exhaust header 92. An engagement initiating inilation pressure supplied to the pipe 102 is similarly effective on the ahead shift controlling relay to connect the expansible chamber 111 of the shift actuator 87 to the exhaust header 92 as indicated by the broken line e. Thus when the control lever is reversed as in fast maneuvering, shifting of the selectorl valve to effect a reversal is prevented until the pressure in the engaged clutch is reduced to approximately its minimum inflation pressure.

It should be noted that the interlocking rclay'valves 130 and 131 delay pressure supply to the oncoming clutch in proportion to the opposite clutch ination pressure, but only during reverse maneuvering operation. Direct response is still attainable whenever the control lever 71 is moved from its neutral position, with both clutches disengaged, to either an ahead or an astern drive controlling position.

To' compensate for the somewhat delayed energization of the oncoming clutch during rapid maneuvering operation of this system, relative to that provided by the first form o'f the invention, a relay valve 135 is provided which is operative to control a passage or pipe 136 bypassing the flow contro'l valve 91'. Whenever the pressure in the portion of the pipe 91 between the flow control valve 91' and the selector valve is above the minimum pressure required for full clutch engagement, this pressure is applied to the relay valve 135 by branch pipe 136 and is operative to shift the relay valve Ymember between a closed position, indicated by the broken lines at g', to an o'pen'bypassing position, indicated at g. This permits a rapid and relatively unrestricted build-up of the inflation pressure applied to the oncoming clutch and to the governor speed adjusting actuator through the pipe 126 and the flow control valve 126' and thus provides for a more rapid advance of the engine governo'r speed setting shaft between its idle and maximum speed and load positions.

As a further refinement of the form of the invention shown in Figure 5, two ow control valves 132 and 133 are interposed in the pipes 102" and 101, respectively. Such valves introduce a time delay in the build-up of interlocking pressures applied to the relay valves 130 and 131, respectively, while permitting relatively unrestricted venting of such interlocking pressures from the relay valves. By properly proportioning the orifices of such ow co'ntrol valves, immediate response or shifting of the selector valve is permitted Without interlocking when the control lever is rapidly actuated between its idle ahead and idle astern positions.

DESCRIPTION-FIGURE 6 In the embodiment of the invention shown in Figure 6, a control lever 140 of a pilot house control stand 141 is operatively connected to a rotary' actuator device 144 by z suitable hydraulic, electrical or mechanical means inditrol stands 66 and 67 of the preceding embodiments. The control shaft 146 is also adapted to be manually operated by a control lever 148 mounted thereon.

The control stand 147 is connected to a suitable source of pressurized uid by a pipe 149 and is adapted upon movement of either control lever or 148 in an ahead direction to deliver an ahead-shift pilot signal to a pipe..

150 or upon movement of either control lever in an astern direction to deliver an astern shift pilot signal to a pipe i The control stand 147 is also adapted to deliver` 151. a variable inflation and speed controlling pressure signal to a pipe 152, such signal being proportional to the angular movement of either control lever from its neutral` position.

A ow control valve 153 interposed in the pipe` 152 corresponds to the ow control valves 91' of the preceding embodiments. T he pipe 152 is connected by two branch pipes 154 and 155 to the inlet ports of two pressure operated, three-way relay valves 156 and 157, respectively, which serve as ahead and astern shift control valves replacing the single four-way, spring cen-` tered and pressure actuated shift valve 88 of the preceding forms of the invention.l The relay valves 156 and,

157 are of conventional design and have valve members which are normally spring biased to provide exhaust connections m and n', respectively, between the clutch inflation and

speed control pipes

101 and 102, respectively, and the engine room exhaust -headerv92. Each relay valve member is shiftable to a second operative position in response to a shift controlling pilot signal applied thereto wherein pressure supplying connections m and n are established between the

pipes

154 and 101 and between the pipes and 102, respectively.

The application of the shift controlling pilot signals from the

pipes

150 and 151 to the shift control relay valves 156 and 157, respectively, is controlled by the interlocking action of two inflation pressure actuated relay valves 158 and 159 corresponding to the interlocking relays 130 and 131 of the embodiment of Figure 5. The valve members of the interlocking relay valves 158 and 159 are normally spring biased to a first position to provide through passages indicated o and p, respectively, between the ahead shift signal pipe 150 and a pipe 150' leading to the pressure sensing unit of the shift control relay valve 156 and between the astern shift pipe 151 and a pipe 151 leading to the pressure sensing unit of the astern shift control relay valve 157,.

respectively. The valve member of the interlocking rclay valve 158 is shiftable to a second operative position o venting the pipe 150' to the exhaust header 92 in response to astern inflation pressure applied thereto from. the

pipes

102 and 102 through a pipe 102". The valve member of the interlocking relay valve 159 is similarly shiftable to a second position venting the pipe 151 to exhaust whenever ahead inflation pressure is suppliedk thereto from the

pipes

101 and 101 through an interconnecting pipe 101".

With the exception of the independent operation of the shift controlling relay valves 156 and 157 and the omission of the flow control valves 132 and 133` and the flow control bypassing relay valve 135, the operation of the embodiment of Figure 6 is essentially the same as that of the form of -the invention of Figure 5.

DESCRIPTION- FIGURE `7 It will be noted that with the embodiments ofthe invention of Figures l and 1a, 5, and 6, when the coni-i 'j trol lever is moved .fronr or through itsV neutral position, there will necessarily be a lag period as the` pressure applied to the oncoming clutch builds up to overcome the action of the spring` 44; before clutch engagement is initiated to pick up the propeller load and start accelerating the masses involved in the propeller. drive system. Since the ow of inflation pressure to the oncoming clutch through the tiow control valves 91' or 153 is proportional to the pressure supplied, such a lag will be proportionally much` longer when the movement of the control lever is limited to a relatively low speed position. Such a lag may be overcome by the operator moving the control handle to a speed position beyond the speed at which he desires to operate with subsequent return of the handle to its desired position. Such operation provides a momentary boost in the initial inflation pressure applied through the ow control valve to the oncoming clutch thus shortening the delay in initial clutch engagement. Such a momentary pressure boost may also be provided automatically with` the supplementary control mechanism shown in Figure 7.

The supplementary control of Figure 7, comprises a pressure operated relay valve 164 which is operable to control the flow of the inflation and speed controlling pressure signal either in the remote control pipe 89 or in the

engine room pipe

91 or 152 of the several preceding embodiments. The relay valve 164 has a valve member which isA normally shiftable by the shiftcontrolling pilot signal from either the ahead or astern

shift control pipe

85 or 86, respectively, to provide a through connection q, between the ends of the pipe 89 separated thereby. The ahead and astern shift

signal supplying pipes

85 and 86 are connected to the opposite ends of a two-way or double check valve 160, similar to 123, through

branch passages

85 and 86, respectively. The valve member of the check valve 160 is shiftable, in response to the oncoming shift controlling signal in one pipe and to the venting of the other, to supply the oncoming shift controlling signal to a pipe 161 connected to the check valve 160 intermediate its ends. The pipe 161 is connected through a flow control valve 161 to the pressure sensing end of the relay valve 164 and to a chamber 165 of a predetermined volume. When the pressure applied to the pressure sensing end of the relay valve drops below a predetermined amount, e.g. 40 p.s.i., the valve member thereof is adapted to be shifted to a second position q' connecting the outlet end of the pipe 89 to a pipe 162. The pipe 162 is in turn connected to the pipe 161 by a pressure regulator valve 163. The regulator valve 163 is adapted to convert the shift controlling signal, e.g. 60 p.s.i., to a predetermined constant pressure, e.g. 30 p.s.i., and to supply such constant pressure to the pipe 162.

The operation of the supplementary control of Figure 7 is as follows, assuming the control stand lever to be actuated from an ahead driving position to an astern driving position. As the control lever passes through its neutral position, the ahead shift control pipe 85 is vented to exhaust through the ahead shift control valve 75. This venting of the line 85 also vents` the pipes 85" and 161, the relay valve 164, and the chamber 165 to exhaust prior to the shifting of the two-way check valve 33.60 in response to the build-up of the astern shift pilot signal supplied thereto above the venting pressure in the ahead shift pipe. This effects a momentary reduction in the pressure applied to the sensing unit of the relay valve 164 and within the chamber 165 below 40 p.si. Consequently, the valve member of the relay 164 is shifted to its second control position wherein the pipe 162 is connected to the outlet end of the pipe 89 thus supplying the constant 30 p.s.i. pressure from the pressure regulator valve 163 to the inflation tube of the oncoming astern clutch. Normal ination and speed control is restored by the relay valve 164` whenever the pressure in the pipe 161 intermediate the ow control valve 161' and. thel chamber 165agan` exceeds 40 p.s.i.` The timing for effecting such restoration of normal inflation and speed' controlA is accomplished by properly relating the volume of the chamber to the size of the orice of the ow control valve 161.

DESCRIPTION-FIGURE 8 The' form of the invention shown in Figure 8 is particularly` adapted for use in those applications requiring high degrees of control and responsiveness such as with multi-engine installations having a single output shaft.

The drive intermediate the engine and propeller shaft is identical with that shown in Figure la, the ahead and astern clutch units respectively being adapted to reverse the driving relation between the engine driven shaft 20 and the input driving shaft 36` of the reverse gear unit 18. As in the embodiments of Figures 1 and 5, the selective energizing and deenergizing of the astern and ahead clutch units are controlled by the operation of a four-way pilotoperated shift valve 88 which is shiftable to either of two shift controlling positions in response to the selective application of shift controlling pressure signals delivered to the ends of the valve actuating cylinder 87 associated therewith or to a centered neutral position provided by the spring centering assembly 113.

This control system features the coordination of clutch engagement with the propeller shaft speed during operation in the clutch slip speed ranges to provide a relatively fast rate of response during reversals from one slip range to the other. For operation above the clutch slip speed ranges this control system is adapted to apply a single high pressure to thev inflation tube of the selected clutch which is sufficient to` maintain full clutch engagement under all engine load and speed conditions between idle andI full speed ahead or astern. Consequently, the speed controlling signal is necessarily regulated and supplied to the governor speed adjusting actuator separately, although coordinated with, the clutch inflation controlling signal. This requires the elimination of the speed controlling two-way check valve connection intermediate the

clutch inflation lines

101 and 102 andthe speed actuator of the preceding embodiments. It will be noted that the governor, the governor speed adjusting actuator and the interconnecting linkages are shown diagrammatically to be similar to those of the rst and second forms of the invention and are therefore designated by the same reference numerals.

The pressure supply for the instant system includes an air receiver 201 which is connectable through a checkvalve-controlled pipe 200 to a suitable air compressor. The receiver is connected to and supplies a constant actuating pressure to the propulsion control system through a pipe 202, Vow through the pipe 202 being controlled by a combined filter and pressure regulator unit indicated at 202A and a manually operable shutoff valve 202B. A branch pipe 202 leading from the pressure supply pipe 202 is adapted to supply pressure through a flow control valve 244 and a pressure operated relay valve 231 to a pipe 232 leading to the pressure inlet 98 ofthe four-way shift control valve 88 for clutch inflation during idle to full speed ahead or astern operation. A second `branch 202" from the pressure supply pipe 202 is controllable by the selective actuation of a valve member 203 of a transfer valve assembly 203 to alternatively supply control pressure to either a pipe 204 leading to a pilot house control stand 210 when the valve member is in. its position indicated by the broken lines at a or to a pipe 204 leading to a similar engine room control stand, not shown, -when the valve member is in its broken-line-indicated position a'.

As shown diagrammatically, the control stand 210 includes a manually operable lever 211 which is secured to a control camshaft 212 rotatably mounted in the stand. The camshaft 212 is provided with four cams axially spaced thereon and indicated at 213, 214, 215

and 216. The cam- 216 is yprovided with a first control lobe G which is adapted tov actuatc ,a valve member 205 of a shutoff valve 206 ,to a closed position whenever the control lever 211 is within its neutral zone. Actuation of the control lever from its neutral zone permits the valve member 205 to be shifted to a second position wherein the pressure supply header 204d is connected to the pipe 204 through an interconnecting branch pipe 204a thus supplying actuating pressure to the several other control elements of the stand. A pressure operated relay valve 207 responsive to the pressure in the supply header 204d is adapted to provide a direct connection between the header 204d and the pressure supply pipe 204 through a branch pipe 204C whenever the pressure in the supply header 204d is in excess of a predetermined pressure. With. this interlocking pressure supply arrangement, a lmomentary loss of control stand operating pressure, which would otherwise occur each time the control lever is actuated through its neutral position, is prevented. It will be appreciated that this feature improves the overall responsiveness of the system.

The cam 213 is similar in function and configuration to the cam 73 of Figure 1, having a shift controlling lobe D thereon adapted to alternatively actuate the `valve member 218 of an ahead shift control valvev 217 to a position supplying a shift actuating pressure to the line 80 from the header 104d or to actuate the valve member 221 of an astern shift control valve 220 to a position supplying an astern shift signalwto the line 81 from the header 204d. When the ahead and the astern shift valve members are not in' actuating contact with the lobe D, as when the control `lever is in its neutral position, they are returnable to a position interconnecting both of the shift control pipes 80 and 81 to the'pilot house exhaust header 2719. As in the embodiment of Figure 1, the pipes 80 and 81 are connectable by the transfer valve member 203', Whenin the positions indicated in broken lines at'c and b, to the

pipes

85 and 86, respectively, which are connected to the opposite ends of the actuator cylinder 87 for shifting the fourway valve.

The cam 215 serves to control the slip engagement of the energized clutch when the control lever 211 is actuated to a control position Within either of the indicated ahead or astern slip ranges. The configuration of the cam 215 is such as to actuate la valve member 223 of a` pressure regulator 222 to interconnect vthe pressure supply header 204d to a pipe 224 `and to supply a variable pressure thereto proportional to the degree of movement of the control lever and of the valve member 223 from their shown neutral positions wherein the valve member 223 engages an arcuate surface of minimum radius on the cam 215 and is adapted to connect the pipe 224 to the exhaust header 219. The arcuate surface defining the neutral zone on` the camv 215 is flanked by two rises of increasing radius F and F Which are adapted to propressively shift the Valve member 223 to increase the regulated pressure supplied lto the pipe 224 throughout the clutch slip ranges for ahead and astern operation, respectively. The two cam rises F and F tereminate in a cylindrical surface which extends therebetween on the side of the cam opposite the neutral zone and defines the maximum opening of the valve member 223 to provide the pressure required for full clutch engagement under idle speed and load conditions. The opposite end of the pipe 224 is connected to a pressure regulator relay valve 225 of the so-called computing type'having an output pressure controlled in accordance with the differential between several pressure control 4signals imposed thereon. The pressure `signal delivered by the pipe 224 to the relay valve 225. provides a first -control signal or set point for controllingthe pressure regulation thereof in accordance with the desired speed of the output shaft. A second controlsignal orfset point for the differential computing relay 225 is provided by and air tachometer 227 through an interconnecting pipe 22S. The tachometer 227 is drivingly connected to the propeller shaft 16, as indicated at 226, and the pressure signal generated thereby is of course proportional to the speed of the'propeller shaft.

' A pressure regulator valve 233 interposed-in a branch 204b of the pressure supply pipe 204 reduces the constant pressure supplied thereto to a lower constant output pressure equal to that pressure requiredl for full clutch engagement under engine idle speed and load conditions and this reduced pressure is supplied to the differential relay valve 225. As indicated above, the differential relay valve is adapted to regulate the flow of fluid pressure from the branch 204b to an outlet pipe 229 in accordance with the set point pressures imposed thereon. The pipe 229 is connectable through an inilation pressure controlled safety relay valve 230 and the inflation pressure supply controlling relay 231 to the inlet pipe 232 of the four-way valve. The inflation pressure sensing unit of the safety relay valve 230 is connected to the pipe 232 by a branch pipe 232". This safety relay valve insures the isolation of the relatively low pressure differential relay valve 225 from the high inflation pressure which is supplied through the relay valve 231 under idle to full speed ahead or astern operating conditions.

The operation of the differential relay 225 is such that a slip speed indicating signal of a given magnitude supplied to the pipe 224 when the output shaft 16 is at rest or rotating at a substantially lower speed causes the relatively unrestricted flow of the pressurized fluid supplied thereto to the energized or oncoming clutch. This imposes a relatively high initial or starting torque vcapacity on the oncoming clutch with resultant rapid acceleration of the output shaft 16. However, as the speed of the output shaft approaches the speed indicated by the control stand regulated set point pressure in the pipe 224, the increasing set point pressure supplied to the relay 225 by the air tachometer 227 causes the differential relay to reduce the pressure supplied to the energized clutch by venting a portion of the pressure previously supplied to the pipe 229 to the exhaust header 92 until the inflation pressure required for the desired speed maintaining slippage is reached. Should the control stand set point pressure in the pipe 224 be reduced to a pressure indicating a desired speed less than that of the output shaft, the computing relay will similarly vent a portion of the clutch inflation pressure to the exhaust header below that required for the desired speed until the output shaft speed indicating set point again matches the set point pressure in the pipe 224.'

A second control stand mounted pressure regulator valve 234 is adapted to supply a speed controlling pressure signal to a pipe 236 and therefrom to the governor speed actuator 67 in accordance with the movement of the control lever 211 between its idle and full speed ahead and astern control positions; a pressure regulating valve member 235 of the regulator valve 234 being maintained in thrust engagement with the surface of the cam 214 and actuated thereby. The surface of the cam 214 is formed on a single radius intermediate its ahead and Vastern engine idle speed controlling positions and maintains the valve member 235 in a position venting the outlet pipe 236 to the exhaust header 219 throughout the neutral and slip range of movement of the cam 214 and the lever 211. At its engine idle speed controlling positions, the cam surface is provided with an initial rise adapted to actuate the valve member 235 to an initial pressure supplying position wherein the minimum pressure required to counterbalance the engine idle maintaining means of the governor 57 and actuator 67 is supplied to the pipe 236. In its idle-to-full speed ahead and astern controlling sectors the surfaces of the cam 214 are provided with rises as indicated at E and E', respectively, which are adapted to shift the valve member 23S to annales T7 progressively increase the speed control pressure `signal supplied to `the pipe -236 nin Vaccordance with'the angular movement of the control lever in either speed increasing direction. o

The flow of the speed controlling pressure signal to the actuator 67 through the pipe 236 is controlled by the orifice of a ow control type ,check valve 237 and a pressure operated relay valve 23S. The relay valve 238 `is operable to provide a through connection between the ends of the pipe 236 separated thereby in response to a predetermined. pressure signal supplied to the pressure sensing unit thereof. In theabsence of such a predetermined pressure applied to its pressure sensing unit, -the relay valve 238 is Yadapted to vent the governor speed actuator 67 to the engine room exhaust header 92.

The cam 216 is provided with a second lobe thereon diametrically opposite end lobe G and` extends arcuately thereof through `an angular sector substantially equal to that subtended by the slip and neutral zones of the convrol lever. 4When the lever V211 is in its neutral or either of its slip Zones, the lobe H thrustably `engages and actuates a valve member 239 of a shutoff valve 240 to a position wherein it provides a connection between a pipe 2594s: and the control station exhaust header 219. When the control lever 211 is shifted `to either of its idle speed controlling positions, `the-lobe H no longer engages `the valve member 239 which `is returnable to a position interconnecting the pressure supply header 2l4d to the pipe 204e.. The pressure thus supplied to the pipe 204e is delivered through branch pipes 204ftand 204g connectedthereto' to the pressure sensing units of the inflation controlling relay r2,31 and 23S, respectively. The flow of pressure fluid to the relays through the branch pipes 204f and 204g lis controlled by flow control valves 241 and ZAL-respectively, interposed therein. By proper selection of orifice size for theflow control valves 241 and 242 and the valve actuating pressures for the relays 231 and` 238, the relay valve 231 will first be actuated to supply full inflation pressure to the engaged clutch prior to the actuation of the relayvalve 238 to `supply speed increasing pressure to the governor speed actuator.

Operation of embodiment of Figure 8 The operation `.of the embodiment of the invention of Figure 8 will generally be apparent from the foregoing description. However, such `operation is outlined briefly below.

Assume the control lever is actuated from its neutral zone to an astern slip position. This initial movement of the control lever causes the valve member 265 `to be shifted to its opened-position Supplying pressureto the control stand supply header 26M. The astern shift valve member 221 has similarly been shifted to its opened position and the shift controlling pressure signal thus supplied to the shift-valve actuator 87 causes that valve Vto be shifted to its astern controlling position. The pressure signal supplied to the differential computing relay V22S by the pressure regulatorvalve 222 in accordance with the adjusted position of the control lever and by the air tachometer 227 inaccordance with the propeller speed causes the differential relay to supply the idle speed full engagement inflation `pressure from the pressure regulator valve 233 tofthe astern clutch through the

pipes

229, 232 and 102 as controlled by the safety relay valve 230, the inflation control valve 231 and the shift control valve it. As the speed of the output propeller shaft approaches the desired speed indicated by the `adjusted position of the control lever the differential relay valve reduces the astern clutch inflation pressure to provide the desired propeller `shaft speed.

If the `control lever`is now actuated to a position within its '.astern engine speed controlling sector, -the resultant'inorlease in the pressure signal in pipe 224 causesithecldifferential relay 225 to initially supply the full output pressure ofthe pressure regulator 233 to the 18 astern clutch. Since the flow of ,duid pressure to the inflation .controlling relay 231 and the speed controlling relay 238'is retarded by the flow control valves 241 and 242, respectively, the pressure supplied through the differential relay `initiates full astern clutch engagement prior to the actuation of the relay valve 231 to provide full supply pressure to the engaged clutch and the subsequent actuation Vof the relay valve 238 to supply the speed controlling signal to the governor speed actuator.

In accomplishing a high speed reversal from the now established astern speed to full speed ahead, the control lever is quickly actuated by the operator to its full speed ahead position. The movement of the control lever 211 and the several cams through their astern slip ranges causes the valve 24u to vent the pipe 204e to exhaust. This rapidly exhauststhe'pressure sensing units of the relay valves 231 and 23S through the ow control valves 241 `and 242 with the consequential venting of the governor speed actuator to reduce the engine speed to idle and the re-establishing of the low pressure connection between the

pipes

229 and 232.

As the several cams pass through their neutral positions and into the ahead slip range the astern shift valve 220 vents the corresponding end of the shift valve actuator to exhaust to permit the oncoming shift controlling signal provided by the valve 217 to actuate the #shift valve to its ahead `controlling position. As the control lever is-rapidly advanced to its full speed ahead position, the pressure signals imposed on the differential computing relay will be such as to initially apply idle speed engaging -pressure of the regulator valve 233 to the ahead clutch to eiect the engagement thereof prior tothefactuation .of the relay valve 231 to provide full supply pressure to the engaged `clutch and the subsequent actuation of the relay valve 238 to permit adjustment of the `actuator- 67 to advance the governor to its maximum speed and load maintaining setting.

The preferred embodiments of the invention have been described in detail for the purpose of explaining the several principles, objects, advantages and features of the invention and the bestknown means of practicing the invention. 1t is to be understood, however, that the invention is not to be considered as limited by this description. Many modifications may be made by the exercise of skill in the art without departing from the scope of the principles of the invention as defined in the following claims.

We claim:

l. A drive control apparatus including two couplings independently operable by fluid under pressure to provide alternative driving connections between a load and a prime mover of torque capacity substantially proportional to the pressure of such fluid and operable upon release of such fluid under pressure to disconnect said load from said prime mover, a power -control motor operable by fluid under pressure to adjust the speed of said prime mover between minimum and maximum limits in proportion lto the pressure of such duid, a first valve means operable to selectively supply and release fluid under pressure to and from either one of said couplings, a second valve means operable to supply fluid under pressure to operate said motor, a control device operable to regulate the pressure of fluid supplied through said first and second valve means to said couplings and motorand including a control element movable from a rio-pressure supply position to either of two full pressure supply positions, and means for controlling operation of said first and second valve meansto control the supply or" fiuid under pressure .to and its release from each of said couplings and said motor in accordance with movement of said control element to and fromits no-pressure supply position.

2. `An apparatus for controlling two couplings independentl-y operable by fluid under pressure to provide a driving connection between a load and Va prime mover asada-e 19 of torque capacity substantially proportional to the pressure of such fluid and operable upon release of such tiuid under pressure to disconnect said load from said prime mover and for also controlling a power control motor operable by fluid under pressure above a predetermined pressure to adjust the speed of said prime mover in proportion to the pressure of such tiud, comprising in combination with said couplings and motor, a iirst valve means operable to selectively supply fluid under pressure to either one of said couplings and at the same time release fluid under pressure from the other coupling, a second valve means operable in response to the supply of fluid under pressure to either one of said couplings'to provide a connection between said one coupling and said motor to thereby supply such fluid under pressure to operate said motor, a control device operable `to regulate. the pressure of uid supplied through said iirst and second valve means to said couplings and motor, said control device including a control element movable from a no-pressure supply position to either of two full pressure supply positions and means for controlling operation of said first valve means to control the supply of fluid under pressure to and its release from each of said couplings in accordance with movement of said control element to and from its no-pressure supply position.

3. A drive control system including two couplings each independently operable by pressurized liuid to provide a driving connection between a load and a prime mover of torque capacity substantially proportional to the effective pressure of such iluid and operable upon release, of such pressurized uid to disconnect said load from said prime mover, a power control motor operable by pressurized fluid to adjust the speed of said prime mover in proportion to the pressure of such fluid, a

`control device operable to regulate fluid pressure for supply to said couplings and to said motor and including a control element movable between two maximum pressure s upply positions through a no-pressure supply position, a rst valve means including a valve member shiftable to selectively supply pressurized uid from said control device to and to release pressurized fluid from l either one of said couplings, a second valve means operable in response to a higher pressure of lluid in either one of said couplings to provide a connection between said power control motor and said one coupling whereby pressurized tiuid as supplied to said coupling is supplied to operate said motor, and means associated with said control device for shifting said valve member to control the supply of fluid under pressure to and its release from each of said couplings in accordance with the movement of said control clement to and from its no-pressure supply position, said last-mentioned means being operable upon operation of said control device element to or through its no-pressure supply position to shift said valve member to a position wherein said member is adapted to simultaneously release tluid under pressure from both of said couplings and to delay further movement of said valve member and thereby the supply of fluid under pressure to the other coupling to permit a reduction in the pressure of uid in said one coupling below a chosen pressure. Y

4. A power plant drive control mechanism comprising,V in combination, two friction couplings independently operable by uid under pressure to provide alternative driving connections between a load and a prime mover of torque capacity substantially proportional to the pressure of such liuid and operable upon release of such fluid under pressure to disconnect said load from said-prime mover, a power control motor operable by fluid above a predetermined pressure corresponding to that required to establish initial full engagement of such couplings to adjust the speed of said prime mover-in proportion to the pressure of such fluid between minimum and maximum limits, a first valve means operable to selectively supply and release uid Vunder pressure to and from said couplings, a second valve means operable in response to the supply of fluid under pressure to either one of said couplings to provide a connection between said one coupling and said motor to thereby supply such fluid under pressure to operate said motor, a' control `device operable to regulate the pressure of fluid supplied through said trst and second valve means to said couplings and motor and including a control element movable between `a no-pressure supply position and either of two full pressure supply positions, means for controlling operation of said first valve means to control the supply of fluid under pressure to and its release from each of said couplings and said motor in accordance with movement of said control element to and from its no-pressure supply position and operable upon movement of said control element to or through its nopressure supplyposition to Vrelease `tiuid under pressure from either 'one of said couplings and said motor, and means associated with said last-mentioned-means for delaying the supply of uid under pressure to the other coupling until the pressureof fluid in said one coupling is reduced below a chosen pressure upon movement of saidcontrol element through its no-pressure supply position.

V5. VAn apparatus for controlling two couplings independently operable by fluid under pressure to provide a driving connection between a load and a prime mover proportional to the pressure of such fluid and operable upon release of such fluid under pressure to disconnect said load from said prime mover and for also controlling a power control motor operable by iluid under pressure above a predetermined pressure vto adjust the speed of said prime mover in proportion to the pressure of such uid, comprising in combination with said couplings and motor, a rst valve means operable to selectively supply uid under pressure to and its release from said couplings, a second valve means operable in response to the supply of fluid under pressure to either one of Vsaid couplings to provide a connection between Vsaid one coupling and said motor to thereby supply such fluid under pressureto operate said motor, a control device operable to regulate the pressure of Huid supplied through said iirst and second valve means to said couplings and motor and including a control element movable from a no-pressure supply position to either of two full pressure supply positions, and means for controlling operation of said rst valve means to control the sup-` ply of iluid under pressure to and its release from each of said couplings in accordance with movement of said control clement to and from its no-pressure supply p0- sition, said last-mentioned means including means operable upon movement of said control element to or through its no-pressure supply position to permit relatively unrestricted actuation of said rst valve means to release fluid under pressure from one of said couplings and to delay further actuation of-said first valve means and thereby the supply of uid under pressure to the other coupling to permit the pressure of uid in said one coupling to be reduced below a chosen pressure.

6. An apparatus for controlling two couplings independently operable by lluid under pressure to provide alternative driving connections between a load and a prime mover of torque capacity substantially proportional to the pressure of such fluid and operable upon release of` such fluid under pressure to disconnect said load from said'prime moverl'and for also controlling a' power controll motor operable by fluid under pressure above a predetermined pressure to adjust Vthe speed of said prime mover in proportion tothe pressure of such fluid between minimum and maximum speed limits, comprising in combination with said couplings and motor, afrst valve means operable toselectively` supply lluid under pressure to either one of said couplings and at the same time'release iluid under pressure from' the `'other coupling,` a secondV valve means operable in relsponse to the supply fofuid under pressure `to` either `one of said couplings to provide `a connection between `said one coupling and said umotor to thereby supply such vfluid under pressure lto operate said motor, a control device operable to regulate the pressure of fluid supplied through said first and second valve means to said couplings and motor and including a control element movable from a no-pressure supply position to either of two full pressure supply positions, means for controlling operation of saidiirst valve means to control thefsupply of fluid under pressure to and its release from each of said couplings in accordance with movement of said control element to and from its no-pressuretsupply position and operable upon movement of said control element to or through its no-pressure supply position to cause said first valve4 means `to release fluid under pressure from either one of said couplings, and interlock means operable in response to lthe pressure of fluid supplied to either one of said couplings to delay the supply of uid under pressure to the other coupling upon movement of said control element through its no-pressure supply position until the pressure of fluid in said one coupling is reduced to below a predetermined pressure.

7. A `drive control system includingrtwo couplings each independently operable by pressurized fluid to pro- 4vide a frictional driving connection between a load and `a prime mover proportional to the effective pressure of `such fluid and operable upon release of such pressurized fluid to disconnect said load from said prime mover, a

-power control motor operable by pressurized fluid to ladjust the speed of said prime mover in proportion to `the pressure of such fluid, a control device operable to regulate fluid pressure for supply to said couplings and to said motor'and including a control element movable between two maximum pressure supply positions throng a no-pressure supply position, a first valve means including a valve member shiftable between rst and second positions wherein said valve member is adapted to selectively supply pressurized fluid from said control device to either one of said couplings and at the same time to release pressurized fluid from theother coupling, said valve member having an intermediate position wherein it is adapted to simultaneously release pressurized fluid from both of said couplings, uid pressure means associated with said control device for shifting said first valve member to its first and second positions to control the supply of liuid under pressure to and its release from each of said couplings in accordance with the movement of said control element to and from its nopressuresupply` position, said last-mentioned means being operable upon operation of said control device element to or through its no-pressure supply position to shift said valve member to its-intermediate position to insure release fluid under pressure from one of said couplings prior to the supply of fluid under pressure to the other coupling, and interlocking valve means operable to open said power control motor to said control device when said control device is supplying pressurized fluid to said rst valve means in excess of apredetermined pressure.

8. A drive control mechanism comprising, in combination, two couplings independently` operable by pressurized fluid to provide a frictional -driving connection between a load and a prime mover of a torque capacity substantially proportional ito the effective pressure of such fluid and operable upon release of such pressurized fluid to disconnect said load from said prime mover, a power control motor operable by pressurized fluid -above a predetermined pressure to adjust the speed of said prime mover between minimum and maximum speed limits in proportion tothe pressure ofsuch fluid, a control device operablellto regulate fluid pressure for supply to said couplings and to said motor and including `a control `element movable between two maximum pressure supply positions through a 11o-pressure. supply position, said control device being adapted to supply pressurized fluid to one of said couplings sufficient to establish and maintain a substantially positive driving connection therethrough when said control device is supplying uid pressure in excess of said predetermined pressure to said motor, a first valve means operable to selectively supply pressurized fluid from said control device to either one of said couplings and atthe same time to release pressurized fluid from the othercoupling, a second valve means operable to supply pressurized fluid from said control device to said motor, `fluid pressure means associated with sad control device and said first valve means for remotely controlling the operation of said first valve means to control the supply of fluid under pressure to and its release from eachof said couplings in accordance with the movement of said control element to and from its no-pressure supply position, and a second fluid pressure means associated with said control device and said second valve means for remotely `controlling the operation of said second valve means to control the supply of fluid under pressure to and its `release from said motor in accordance with the movement of said control element to and from its no-pressure supply position.

9. A drive control system including two couplings individually operable-by fluid under pressure to provide a controllable slip frictional driving connection between a load and a prime mover of a torque capacity substantially porportional to the effective pressure of such fluid below a predetermined pressure and to provide a substantially positive driving connection therebetween when the pressure of such fluid is above said predetermined pressure and operable upon release of such fluid under pressure to disconnect said load from said prime mover, a power control motor operable by fluid pressure above said predetermined pressure to adjust the speed of said prime mover in proportion to the pressure of such fluid, a coupling control pipe connected to each of said couplings, a speed control pipe connected to `said power control motor, a first valve means intermediate said coupling control pipes and including a valve member shiftable in response to a differential in the fluid pressure in said coupling control pipes to interconnect the coupling pipe having the higher fluid pressure therein to said speed control pipe, a second valve means including a second valve member shiftable between two extreme positions for selectively supplying fluid under pressure to either `one of said coupling control pipes while at the same time releasing fluid under pressure from the other coupling control pipe and having an intermediate position for simultaneously releasing fluid under pressure from both of said coupling control pipes, a double-acting motor means associated with said second valve means and operable by uid pressure `to selectively shift said second valve member toward either of its extreme positions, and means associated with said second valve means and operable upon release of fluid pressure from said doubleacting motor means to shift said second Valve member Vto its intermediate position, a control device operable to regulate fluid pressure for supplylto said couplings and to said motor through said valve ,means and including a control element movable betweentwo maximum pressure supply positions through a `nor-pressure supply position, and means associated jwith said control device and operable to selectively supply Afluid pressure to said double-acting motor means to control the shifting of -said second valve member to control the supply of fluid under pressure to and its release from each of saidcouplings and said power control motor in accordance with the movement of saidcontrol element to and from its no-pressure supply position, said-last-mentioned means being operable upon operation or" said control device element to or through its no-pressure supply position to release fluid pressure from said double-acting motor means to shift said second valve member to its intermediate position wherein it is adapted to simultaneously aeaenee release fluid under pressure from both of said Vcouplings and to delay further movement of said valve member and thereby the supply of fluid under pressure to the other coupling to permit a reduction in the pressure of iluid in said one coupling below a chosen pressure.

lO. A drive control system including two couplings individually operable by uid under pressure to provide a controllable lslip frictional driving connection between a load and .a prime mover of a torque capacity substantially proportional to the effective pressurev of such fluid below a predetermined pressure and to provide a substantially positive driving connection therebetween when the pressure of such iluid lis above said predetermined pressure and operable upon release of such iiuid under pressure to disconnect said load from said prime mover, a power control motor operable by fluid pressure above said predetermined pressure to adjust the speed of said prime mover vin proportion to the pressure of such fluid, a coupling control pipe connected to each of said couplings, a speed control pipe connected to said power control motor, a valve having an inlet port connected to each of said coupling control pipes and an outlet port connected to said speed control pipe and including a valve member shiftable in response to a differential in the fluid pressure in said coupling control pipes to interconnect the coupling pipe having the higher Huid pressure therein to said speed control pipe, a fourway valve including a valve member shiftable between two extreme positions for selectively supplying iluid under pressure to either one of said coupling control pipes while at the same time releasing fluid under pressure from the other coupling control pipe and having an intermediate position for simultaneously releasing uid under pressure from both of said coupling control pipes, a double-acting motor means associated with said fourway valve member and operable by fluid pressure to selectively shift said valve member toward either of its extreme positions, and means associated with said fourway valve member and operable upon release of lluid pressure from said double-acting motor means to shift said four-way valve member to its intermediate position, a control device operable to regulate fluid pressure for supply to said couplings and to said motor through said valves and including a control element movable between two maximum pressure supply positions through a nopressure supply position, and means associated with said control device and operable to selectively supply iluid pressure to lsaid double-acting motor means to control the shifting of said valve member to control the supply of fluid under pressure to and its release from each of said couplings and said power -control motor in accordance with the movement of said control element to and from its no-pressure supply position, said last-mentioned means being operable upon operation of said control device element to or through its no-pressure supply position to release uid pressure from said double-acting motor means to shift said four-way valve member to its intermediate position wherein it is adapted to simultaneouslyv release lluid under pressure from both of -said couplings and to delay further movement of said valve memberand thereby the supply of fluid under pressure to the other coupling to permit a reduction in the-pres- I sure of fluid in said one coupling below a chosen pressure.

1l. Al drive control system comprising, in combination, two couplings individually operable by fluid under pressure to provide a controllable slip driving connection between a load and a prime mover of speed and torque capacity substantially proportional to the effective pressure of such iluid below a predetermined pressure and to provide a substantially positive driving connection therebetween when the pressure of such iiuid is at'or above said predetermined pressure and operable upon release of such fluid under pressure to disconnect said load from said prime mover, a power control motor operable by fluid pressure above a predetermined pressure to adjust the V24 speed of said prime mover .in proportion to the pressure of such luid, a speed control pipe connected to said power control motor, a iirst valve means operable to control the supply of pressure fluid to and from said speed control pipe, means associated with said tirst valve means and operable by uid pressure to actuate said valve means to control the supply of pressure fluid to and from said speed control` pipe, a coupling control pipe connected to each of said couplings, a second valve means operable between two extreme control conditions to selectively supply fluid under pressuretto either one of said coupling control pipes while at the 4same time releasing iluid under pressure from the other coupling control pipe and an intermediate control condition for simultaneously releasing fluid under pressure from both of `said coupling control pipes,'m`otor means associated with said second valve means and oper'. able by uidV pressure to selectively actuateV second valve means to either of its Vextreme control conditions, and Vmeans associated with said second valve means and operable upon release of fluid pressure from said motor means to actuate said second valve means to its intermediate control conditiom ar control device operable to progressively regulate Vfluid pressure for supply to said couplings and to said motor through said valve means and including a control element movable between two maximum pressure supply positions through a no-pressure supply position, and means associated with said control device and operable to selectively supply iluid pressure to said valve actuating means to control the actuation of said valve means to control the supply of fluid under pressureto and its release from each ofsaid couplings and said power Vcontrol motor in accordance with the movement vof said control element to and fromV its no-pressure supply position.

12. An apparatus for controlling two individual couplings operable by fluid under pressure to provide a con'- trollable slip driving connection between a load and a prime mover to a degree proportional to the pressure of such iluid below a predetermined pressure and to provide a substantially positive driving connection therebetween when the pressure of such uid is above said predetermined pressure and operable upon release of such iluid under pressure to disconnect said load from said prime mover, and for also controlling a power control motor operable by Huid pressure to adjust the speed of said prime mover between minimum and maximum speed limits in proportion to the pressure of such fluid above said predetermined pressure, comprising in combination with said couplings and motor, a coupling control pipe connected to each of said couplings, a speed control pipe for said power control motor, a two-way check valve having an inlet port connected to each of said coupling control pipes and an outlet port connected to said speed controlY pipe and including a valve member shiftable in response to a iluid pressure differential in said coupling control pipes to interconnect the coupling pipe having the higher fluid pressure therein to said speed control pipe, a four-way valve means including a valve member shiftable between two extreme positions for selectively supplying fluid under pressure to either one of said coupling control pipes while at the same time releasing fluid under pressure from the other coupling control pipe and having an intermediate position for simultaneously releasing iiuid under` pressure from both Vof said coupling control pipes, a doubleacting motor means associated with said four-way valve member and operable by. iluid pressure to selectively shift said valve member toward its extreme positions, means associated with said four-way valve member and operable upon release fluid pressure from said motor meansto shift said four-way valve member to its intermediate positions, and a control device including a control element movable from a no-pressure supply position to either of two full pressure supply positions to progressively regulate the pressure of uid supplied through said four-Way valve means to said couplings and motor, and shift valve means `l toperable inV accordance with `*movement of 'said contr-ol velement to and from its no-pressure supply position to selectively control the supply and release of iluid pressure --to-and from said double-acting motor means to thereby .control the shifting of said four-way valve member to control the supply of fluid under pressure to and its release from each of said couplings and said motor.

i 13. A mechanism for controlling power transmission .between a load and a prime mover comprising, in combination, a power control motor operable by liuid pres- `fsure above a predetermined pressure to adjust the speed of said prime mover in proportion to the pressure of such `fluid, two couplings individually operable by duid under pressure to provide a controllable slip driving connection .between said load and said prime mover of a torque capacity substantially proportional to the effective pressure of such fluid below saidpredetermined pressure and Ato, provide a substantially positive driving connection therebetween when the pressure of such fluid is above said predetermined pressure and operable upon release of such .fluid under pressure to disconnect said load from said tprime mover, a speed control pipe connected to said ,power control motor, a first flow control means associated `with said speed controlpipe and adapted to restrict 4theiflowofA fluid to said speed `control motor and to permit theunrestricted venting of fluid from said motor, a coupling control pipe connected to each of said couplings, a first valve-means intermediate said coupling control pipes and operable in response to a differential in the iluid Vpressure in said coupling control pipes to interconnect the ,coupling `pipe having the higher fluid pressure therein Ato said speed `control pipe, a second valve means operable between two extreme control conditions wherein fluid lunder pressure is selectively supplied to either one of said .coupling control pipes while at `the same time releasing fluid under pressure from the othercoupling control pipe and an intermediate control condition wherein fluid under pressure is simultaneously released from both of said `coupling control pipes, motor means associated with said second valve means and operable by fluid pressure to y selectively actuate said second valve means toward either .of its extreme control conditions and operable upon `release -of fluid pressure therefrom to shift said second `valve means to .its intermediate control condition, a `control `device .operable to progressively regulate fluid pressure for supply to said couplings and to said motor through said valve means and including a control element movable between two maximum speed and load pressure supply positions through a neutral no-pressure supply position, a pressure supply pipe interconnecting said device and said second valve means, a second flow control means associated with said last-mentioned pipe and adapted to restrict the ow of fluid to said second ,valve means and to Vpermit the relatively unrestricted `venting `of fluid from said second valve means, a third valve means associated with said control device and operable to selectively supply and release fluid pressure 4to and from said motor means to control theactuationf of said ,second valve means in accordance with the movement of Isaid` control element to and from its no-pressure supply -neutralpositiom and third flow control means intermedi- `ate said third valve means and said motor means and )adapted to restrict the fiow of fluid towards said motor means ,and to permit the relatively unrestricted venting thereof `whereby operation of said control device element to or through vits no-pressure supply position causes said third valve means to quickly vent fluid pressure from said `,motor means thereby causingA said motormeans to actuate said second valve means from` one of its eXtreme 'control conditions to its intermediate control conditions twhe'reinit is adapted to release iluid under` pressure from the previously engaged one of said couplings and to delay ractuationof said second valve means toits other extreme control,condition `and thereby the` supply of uid under `pressuretothe other ctmplingto` permit `a reduction in pressure and to provide a substantially positive Vdriving connection therebetween when the pressure of suchuid is above said predetermined pressure and operableupon release of such iluidunder pressure toV disconnect said load from said prime mover, a speed control pipe connected to said power control motor, a first iiow control means associated with said speed control pipe and adapted to Arestrict the ow of fluid to said speed control motor and to permit the unrestricted venting of fluid from said motor, a coupling control pipe connected to each of said couplings, a first valve means intermediate said coupling control pipes and operable in response to a differential inthe iluid pressure in said coupling control pipes to interconnect the coupling pipe having the higher fluid pressure therein to said speed control pipe, a second valve `means operable between two operating conditions where- ,in` uid under `pressure is alternatively supplied to one `of said coupling control pipes while at the same time releasing fluid under pressure from the other coupling control pipe and an intermediate operating condition wherein fluid under pressure is simultaneously released Ifrom both Yof said coupling control pipes, motor means associated withv said second valve means and operable by fluid pressure to selectively actuate said second valve means toward either of its extreme operating conditions and operable upon release of fluid pressure therefrom `to shift said second valve means to its intermediate operating condition, a control device operable to progressively regulate fluid pressure for supply to said couplings and to said motor through said Valve means and includ- -ing a control element movable between two maximum speed and load pressure supply positions through a neutral no-pressure supply position, a pressure supply pipe interconnecting said device and said second valve means, a second ow control means associated with said last- Amentioned pipe and adapted to restrict the flow of fluid to said second valve means land to permit the relatively unrestricted venting of fluid from said second valve means, and a third valve means associated with said control device land operable to selectively supply and release iluid pressure to and from said motor means to control the actuation of said second valve means in accord- .ance with the movement of said control element to and from its `no-pressure supply neutral position.

15. In a mechanism for controlling power transmis- VAsion between a load and a prime mover, the combination comprising a power control motor operable by fluid pressure above a predetermined pressure to adjust the `speed of said prime mover in proportion to the pressure of such uid, two couplings individually operable by fluid under pressure to provide a controllable slip driving connection between said load and prime mover ,of a speed and torque capacity substantially proportional to the effective pressure of such duid below said predeterminedpressure and to provide a substantially positive `driving `connection therebetween when the pressure ,of

.suchfluid is above said predetermined pressure and operable upon release of such fluid Linder pressure to disconnect said load from said prime mover, a speed control pipe connected to said power control motor, a cou- .plingrcontrolpipe connected to each of said couplings,

a first ,valve means intermediate said coupling `control pipes and operable in response `to a differential in .the uidpressure in` said coupling control pipestofintercon- 27 Y Y nect the coupling pipe having the higher fluid pressure therein to said speed control pipe, -a second valve means operable between two extreme operational conditions wherein fluid under pressure is selectively supplied to either on of said coupling control pipes while at the same time releasing liuid under pressure from the other coupling control pipe and an intermediate operational condition wherein both of said coupling control pipes are simultaneously vented, motor means associated with said second valve means andk operable by fluid pressure to selectively actuate said second valve means toward either of its extreme operational conditions and operable upon release of tluid pressure therefrom to shift said second valve means to its intermediate operational condition,

fa control device operable to progressively regulate uid pressure for supply to said couplings and to said motor through said valve means and including a control elementmovable between two maximum speed and load pressure supply positions through a neutral no-pressure supply position, Va pressure supply pipe interconnecting said device and said second valve means, and a third valve means associated with said control device and operable to selectively control the supply and release fluid pressure to `and from said motor means to control the actuation of said second valve means in accordance with the movement of said control element to and from its nopressure supply neutral position.

16. The combination set forth in claim and including a flow control means intermediate said third valve means and saidmotor means and adapted to restrict the flow of Huid towards said motor means and to permit the relatively unrestricted venting thereof whereby operation of said control element to or through its nopressure supply position causes said third valve means to quickly vent fluid pressure from said motor `means thereby causing said motor means to actuate'said second valve means to its intermediate operational condition wherein it is adapted to release fiuid 'under pressure from one of said couplings, said ilow control means delaying the supply of actuating pressure fluid to said motor means to effect further movement of said valve member towards its`other extreme operational condition thereby delaying the supply of fluid under pressure to the other coupling to permit a reduction in the pressure of uid in said one coupling below a chosen pressure.

17. The combination as set forth in claim 15 and including interlocking valve means intermediate said third valve means and said motor means and operable in response to the pressure of iiuid supplied to either one of said couplings to permit relatively unrestricted venting 'of said motor means to return said second valve means to its intermediate operational condition from one of said extreme operational conditions upon actuation of said control element to or through its no-pressure supply position and to prevent the supply of tluid under pressure to said motor means to shift said second valve means towards the other of its extreme operational conditions and thereby the Supply of pressure to the other of said couplings until the pressure of said one coupling is reduced to or below said predetermined pressure.

18. The `combination set forth in claim 15 and including a now control means intermediate said control device and said lsecond valve means yand adapted to restrict the ow of control device regulated pressure fluid towards said couplings and power control motor and -to permit the relatively unrestricted venting of fluid therefrom, and relay valve means operable to bypass said ow control means in response to the supply of Huid above said predetermined pressure to said second valve means thereby permtiting the relatively unrestricted supply of control device regulated pressure uid through said second valve means to one of said couplings and said power control motor after a postve driving connection nas been initially established through said one coupling.

19. In a mechanism for controlling transmission of power between a load and a prime mover, the combina- 28 tion comprising aprime mover control includinga motor operable by fluid pressure to adjust the speed and torque capacity of said prime mover in proportion' toA the pressure of such fluid, a pipe connected to said motor, a first valve means associated with said pipe operable to control fluid liow therethrough, and means lassociated with/ Isaid first valve means and operable by uid pressure to actuate said valve means to control the supply of pressure fluid to and from* said power control motor, two couplingsindividually operable by uid under pressure to provide a controllable slip driving connection between said load and prime mover of a speed and torque casure is selectively supplied to either one ofsaid couplingv v connected pipes while at the same time releasing fluid under pressure from the other coupling connected pipe and an intermediate operational condition wherein both of said coupling connected pipes are` simultaneously vented, double-acting motor means associated with said second valve means and operable by fluid pressure supplied to opposite ends thereof to selectively actuate said second valve means toward either of its altern-ative operational conditions and operable upon release of fluid pressure from both ends thereof to shift said second valve means to its intermediate operational condition, a control device operable to progressively regulate uid pressure for supply to said couplings and tosaid motor through said rst and second valve means and including a control element movable between two maximum speed and load pressure supply positions through a neutral no-pressure supply position, a pressure supply pipe interconnecting said device and said second valve means, a third valve means associated with said control device and operable to selectively control the supply and release fluid pressure to and from the opposite ends of said motor means to control the actuation of said second valve means in accordance with the movement of said control element to and vfrom its no-pressure supply neutral position, and two pipes interconnecting said third valve means to opposite ends of said motor means.

20. In a mechanism for controlling transmission of power between a load and a prime mover, the combination comprising apower control motor operable by uid pressure to adjust the speed and torque capacity of said prime mover in proportion .to the pressure of such iiuid, two couplings individually operable by liuid under pressure to provide a controllable slip driving connection between said load and prime mover of a speed and torque capacity substantially proportional to the elective pressure of such uid below a predetermined pressure and to provide a substantially positive driving connection therebetween when theY pressure of such uid is above said predetermined pressure and operable upon release of such fluid under pressure to disconnect said load from said prime mover, a speed control pipe connected to said power control motor, a rst valve means operable to control the supply of pressure fluid to and from said speed control pipe, means associated with saidrst valve means and operable by uid pressure to actuate said valve means to control the supply of pressure uid to and from said speed control pipe, a coupling control pipe connected to each of said couplings, second valve means operable between two extreme operational conditions wherein fluid under pressure is selectively supplied to either one of said coupling control pipes while at the same timoreleasing fluid under pressure from the otherA coupling control pipe and an intermediate'operational condition