US2827768A

US2827768A - Hydraulic circuit with flow divider

Info

Publication number: US2827768A
Application number: US559645A
Authority: US
Inventors: Joseph F Ziskal; Eugene P Virtue
Original assignee: International Harverster Corp
Current assignee: Navistar Inc
Priority date: 1956-01-17
Filing date: 1956-01-17
Publication date: 1958-03-25
Anticipated expiration: 1975-03-25

Description

March 25, 1958 Filed Jan. 17, 1956 J. F. ZISKAL ETAL- HYDRAULIC CIRCUIT WITH FLOW DIVIDER 4 Sheets-Sheet 1 INVENTORS.

March 25, 1958 J. F. ZISKAL ETAL HYDRAULIC CIRCUIT WITH FLOW DIVIDER 4 Sheets-Sheet 2 Filed Jan. 17, 1956 30 28 37 1 23 424 2.5 47 34 v INVENTORS. 26 H flag 0A a 40 4.? feyeyze %224(e March 25, 1958 J. F. ZISKAL. ETAL 2,827,768

HYDRAULIC CIRCUIT WITH FLOW DIVIDER Filed Jan. 17, 1956 4 Sheets-Sheet s IN VEN TORS.

104 105 J wf flysaz z @226 f al age Filed Jan. 17, 1956 March 25, 1958 J. F. ZISKAL ETAL 2,827,758

HYDRAULIC cmcurr WITH FLOW DIVIDER 4 Sheets-Sheet 4 62 IN VEN TORS- United States Patent *Ofi ice 2,827,768 P atented Mar. 25, 1958 HYDRAULIC CIRCUIT WITH FLow urvmnn Joseph F. Zishal, Broohfield, and Eugene F. Virtue, Tinley Park, 51]., assignors to International Harvester Company, a corporation of New Jersey Application January 17, 1956,, Serial No. 55?,45

6 Claims. (Cl. oil-97) This invention relates to a fluid flow dividing mechanism. More in particular this invention relates to a mechanism for dividing the flow of a source of fluid under pressure whereby the flow of fluid delivered to one outlet thereof is regulated or metered and alternate means for discharging excess fluid from said source at low pressure to another outlet thereof or making available said excess fluid at high pressure fora secondary purpose.

As an example of the utility of such a device attention is directed to the fact that wheel type tractors are now manufactured which employ hydraulic power steering mechanisms of the kind which requires the delivery of fluid at a substantially constant pressure during the operation thereof. 'For this purpose it is the practice to provide a separate hydraulic pump on the tractor to provide fluid under substantially constant-pressure when the power steering motor is in operation and by-passing the fluid when the power steering motor is motionless or at rest. Frequently the same type of tractors are provided with hydraulic lift mechanisms for elevating associated implements in transport position. For example a tractor may be connected to a plow whereby the plow may be raised hydraulically to facilitate transportation thereof from one place to another. Thus a single tractor may have two or more independent hydraulic systems requiring an individual pump for each system.

In order to'reduce costs the primary purpose of this invention is to provide an hydraulic circuit or system having but a single hydraulic pump which system will power an hydraulic steering motor of the type described and, in addition thereto, one or more secondary hydraulic motors such as hydraulic rams.

Another object of this invention is to provide an hydraulic flow divider valve arrangement adapted to deliver through one outlet thereof fluid at a metered rate and at substantially constant pressure and a second outlet adapted to bypass excess fluid under pressure for discharge thereof or delivery to a second hydraulic motor and control valve therefor.

These and other desirable objects inherent in and encompassed by the invention will be more readily understood h'om the ensuing description, the appended claims and the annexed drawings wherein:

Figure 1 is an hydraulic system or circuit included in this invention, in schematic form, diagrammatically illustrating the flow of fluid to a power steering motor at rest and a second fluid motor also at rest.

Figure 2 is similar to Figure 1 except that it illustrates the flow of fluid when the second fluid motor is in operation.

Figure 3 illustrates the construction, in section, of the flow control valve or flow dividing valve of this invention.

Figure 4 illustrates a form of the invention in which the hydraulic circuit is modified slightly over that shown in Figure 1.

Figure 5 is similar to that of Figure 4 except that it 2 illustratesthe flowof fluid when the second fluid motor is in operation.

Referring to the drawings illustrating a preferred embodiment of this invention, generally indicated at 10, con sists of afirst control valve 11 and a second control valve 12, a servo-motor assembly 13 including a first fluid motor 67, a second fluid motor 14, a fluid pump 15 which may include a reservoir 16, and a fluid flow dividing mechanism 17. The fluid flow dividing mechanism 17 comprises a fluid flow regulating valve 18 operably controlled by a ram 19, a fluid flow dividing valve 20, and may optionally include a'relief valve 51. The aforementioned elements are interconnected together suitably by various conduits, tubes or fluid passages'to form a fluid circuit or system as hereinafter described.

A novel and ingenious feature of this invention is the inclusion of the fluid-flow dividing valve 20. The primary function of this valve 20 is to meter a first portion of fluid flow entering the inlet port 21 thereof for delivery to a-flrst outlet port 22 at a substantially constant rate of fluid flow. The excess portion of fluid 'flow entering the inlet port 21 over and above that delivered to the first outlet port 22 is directed to a second outlet port 23. The construction of the fluid flow dividing valve 20 will now be described.

Referring to Figure 3 the fluid flow dividing valve 20 consists of a housing 24 having a large longitudinalhole 25 therethrough. A rear head member 26 is positioned at one end of the hole 25 and held rigidly to the housing 24 by any one of the various commonly known methods such as a pressed fit or by providing an enlargement .27 of the hole 25 forming an abutting shoulder 28 for the head member 26 for preventing inward movement thereof. Outward movement of the head member 26 may be restrained by employing a snap ring 29 suitably received in an annular groove 30 in the housing 24 and a corresponding annular groove 31 in the head member 26. A fluid seal 32 may be disposed circumferentially about the head member 26 to prevent fluid leakage therethrough. A front head member 33 is rigidly mounted in the opposite end of the hole 25 similarly to that described for the rear head member 26.

The inner portion of the front head member 33 is provided with a seat element 34 adapted to anchor one end of a captive helical spring 35.

Within the housing 24 is disposed slidably in the hole 25 a reciprocable valve member 36. The member 36 is provided with a large bore 37 adapted to accommodate the other end of the spring 35, said bore extending adjacent the rear end of the member 36 to form a seat 33 for the captive spring 35. A small bore or first metering passage 39 is provided in one end portion 41 of the member 36 to communicate for fluid flow the large bore 37 with a chamber 48 formed by the housing 24, head member 26 and one end portion 41 of the member 36. Thus it will be seen that the reciprocable valve member 36 is urged rearwardly by the spring 35.

Adjacent the rearward end of the reciprocable valve member 36 is a large or Wide circumferential groove 42 of suflicient axial length to effect registration with the inlet port 21 for fluid flow irrespective of axial movement of the valve member 36. The circumferential groove 42 is 'communicatively connected for fluid flow to the chamber 46 by means of one or more channels 43 longitudinally disposed in the periphery of the valve member 36 as best shown in Figure 3. Thus the inlet port 21 is always communicatively connected for fluid flow to the large bore 37 of the valve member 36 through the channel 43, chamber 40 and small bore or first metering passage 39. The second outlet port 23 is positioned to register with land 44 when the reciprocable valve member is in the position shown in Figure 3 thus preventing fluid flow from the inlet port 21 to the second outlet port 23. However, when the fluid pressure at the inlet port;21 reaches a predetermined limit set by the compressive characteristics of the spring 35, the fluid pressure ,acting on the annular surface '45 formed by the groove .42 and land 44 and the rearward end of the member 36 adjacent the chamber 40 causes forward movement of the valve member 36'which movement permits flow of fluid from the groove 42 to the second outlet port 23. From this it can be been that the valvingby the relation of the land 44 wtih the housing 24 throttles the flow of fluid from'the groove 42'to the second outlet port 23 :because the spring 35 urges the valves member 36 rearwardly and the forward motion of the'member 36 must beca used by fluidpressurein the groove 42 acting on V .the annular surface 45 and the rear end of the member 36 to compressthe spring 1 It: will be noted in Figure 3 that the forward end annular face 47 of the reciprocable valve member 36 is positioned to register with the first outlet port 22 to form a second fluidmetering passage 48 which communicates for fluid flow the bore 37 with the first outlet port 22. However, asf'the valve member 36 moves forwardly fluid flow through the'second fluid metering passage 48 is progressively restricted or throttled and becomes completely closed when the valve member 36 reaches its extreme forward limit. The forward movement of the valve member 36 is limited by the annular portion 49 of the seat 34 serving as a stop means when the annular face 47 is in abutting relation thereto.

Adjacent and rearwardly of the annular face 47 of the 'valve member 36 is a small annular groove 46 positioned to communicatively register with the first outlet port 22 irrespective of the axial position or movement of the valve member 36. 'A u'ansversely disposed small port or snubbing port 50 in the valve member 36 is provided to connect communicatively for fluid flow the bore 37 with the small annular groove 46. Thus the snubbing port'50 is always in communication with the first outlet port 22. through the groove 46. The purpose of the snubbing port 50 is to prevent the stoppage of fluid flow to the first outlet port 22 during periods when the system 'is subjected to momentary pressure surges of suflicient magnitude to move the member 36 forwardly to its limit thus closing the second metering passage 48. The

port has in such instances the eifect of snubbing the sudden forward surge of the member 36 and allows fluid to enter the first outlet port 22 at such times to feed fluid to the servo-motor assembly 13. Also when the servomotor assembly 13 is actuated momentarily the port 50 snubs or dampens any chattering tendency of the member 36. 7

From the foregoing it can be seen that when fluid is delivered to the inlet port 21 at low pressure, the entire fluid flow passes from the inlet port 21 to the groove 42, thence through the channel 43 to the chamber 4% thence through the small bore or first metering passage 39 to the large bore 37 of the valve member 36, thence through both the snubbing port 50 and associated groove 46 and the second fluid metering passage 48 to the first outlet port 22. Under low pressure conditions none of the fluid passes to the second outlet port 23 because the land 44 is in complete registration with the second outlet port 23; 7

Now as the fluid flow at the inlet port 21 increases the pressure differential between the chamber 49 and the opening formed by the large bore 37 also increases due to the restriction of fluid flow through the small bore or first fluid metering passage 39. This pressure differential when of suflicient high magnitude causes forward movement of the member 36 thereby further compressing the captive spring 35. The forward movement of the member 36 results in that the second fluid metering passage 48 is progressively restricted and the fluid is throttleci 4 V therethrough. From this it can. be seen that as the reciprocable valve member 36 is progresively moved for= wardly the metering of fluid flow to the first outlet port 22 is shifted from the first fluid metering passage 39 to the second metering passage 48; When the member 36 moves forwardly to begin throttling fluid flow through V the second metering passage 48 a corresponding'backpressure is created in. the opening formed by the large bore 37 which back-pressure reduces the pressure dif ferential between the chamber 40 and the opening formed by the large bore 37 as the fluid passes through the fluid restriction caused by the first fluid metering passage 39. Thus; the valve member 36 moves forwardly thereby throttling fluid through the second'fluid meter ing passage 48 to a point where the above described back-pressure augmented by the urging of the spring 35 balances the pressure of fluid in the groove 42 and chamber 49. As the fluid flow continues to increase at the inlet port 21 the. second fluid metering passage 48 is progressively restricted and the fluid is throttled correspondingly therethrough. The forward movement of the'valve member 36 causes the groove 42 to register with the second outlet port23 thereby by-passing the excess fluid therethrough. 'Now in the case of sudden pressure surges when the fluid pressure at the inlet port 21 rises toa predetermined pressure limit, the valve member 36 will have momentarily at least reached its extreme forward position whereby the second fluid metering passage is completely closed and the only fluid flow to the first outlet port 22 is through the snubbing port 50 and associated annular groove 46. Thus it may be seen that fluid flow to the first outlet port 22 is maintained at substantially a constant rate or pressure and the excess fluid discharged through the second outlet port 23. e

The relief valve 51 of Figures 1 and 2 may be said to be optionally provided unless the capacity of the pump 15 appreciably exceds the fluid delivery necessary to move the reciprocable valve member 36 of the dividing valve 2t) to its extreme forward position as previously described. The relief valve 51 may be of the ordinary known check valve design adapted to permit flow of fluid therethrough when the pressure exceeds' a predetermined value. 7 The relief valve 51 in this instance may be comprised of an inlet port 52 and an outlet port '53, a slidable plunger 54 urged in seating relation with a seat-55 by a captive spring 56. The fluid under pressure entering the inlet port 52 of the valve 51 acts upwardly to urge upward movement of the plunger 54 against the force of the spring 56to unseat the plunger 54 thereby allowing the fluid to escape to the outlet port 53 thereof in a commonly known manner. From this it is evident that the compressive characteristics of the spring 56 determine the fluid pressure at the inlet port 52 necessary to actuate movement of the plunger 54 to open therrelief valve 51 allowing the'fluid to escape therethrough to the outlet port 53 thereof. An ordinary well known ball-type check valve would function similarly. a .The fluid pressure regulating valve 18' including the control ram 19 therefor comprises essentially a ball valve wherein the ball 57 -is normally urgedin seating relation with a seat '58 similar to the known balltype check valve. The regulating valve 18'is providediiwith an inlet port 59 andan outlet port 60. jAs will be noted from Figure2 the ball 57 is urged into seating; relation with the seat 58 by the spring 61. Thus it can be "seen that normally the regulating valve 18 is closed as, the ball 57 is kept seated by fluid under pressure at the inlet port 59 thereof actingon'the ball coupled with the urg ing of thespring61. It is also evident that in order to unseat the ball 57 a downward force must be applied to 7 the ball 57 of suflicient magnitude to overcomethe .fluid pressure entering the inlet port 59 and acting upwardly on the ball '57 as Well as the upward urging of the spring 61 One way for applying the necessary force to unseat the ball '57 of the regulating valve 18 is by means of a small single acting fluid rain 19. The ram 1'9 may be of the ordinary known type having a piston 62 with a work member "63 rigidly connected thereto.

The ram 19 is provided with a port 64 which is adapted to conduct fluid under pressure into the enclosure 65 for acting on the piston 62 to urge the work member 63 in a downward direction. The lower end 66 of the work member 63 abuts or engages the ball 57 and when sufiicient fluid pressure enters the enclosure 65 the ball 57 is forced downward to unseat thereby opening the regulating valve 18 to discharge fluid from the inlet port 59 thereof to the outlet port 60 thereof. When the fluid pressure is reduced in the enclosure 65 the spring 61 urges the piston 62 upwardly to reseat the ball 57 to close the regulating valve 18 and the fluid in the enclosure 65 is forced out the port 64. Thus by controlling the fluid pressure at the port 64 of the ram 19 the flow of fluid from the inlet port 59 to the outlet port 6% of the regulating valve 18 may be throttled from a closed position to a fully open position.

The fluid pump 15 and associated reservoir 16 may be of any of the well known types and for purposes herein maybe described as any source of fluid under pressure. For example an ordinary gear pump provided on many well known tractors is quite satisfactory for use in the fluid circuit of this invention.

As previously mentioned the fluid circuit of this invention includes a servo-motor assembly 13 and 'a second fluid motor 14. The servo-motor assembly 13 is of the type wherein fluid is by-passed therethrough when the servo-motor assembly 13 is motionless. An example of such a servo-motor assembly 13 is a power steering device. The servo-motor assembly 13, as schematically illustrated in Figures 1 and 2, may comprise a two-way acting fluid cylinder 6'] (schematically indicated) associated'with theground engaging front wheels of a tractor or other vehicle. The front Wheels of the vehicle (not shown) are associated with core element 68 of a steervalve 69. A manually operable steering wheel (not shown) is associated with a valve sleeve element 70. A

pairof pipes

71 and 72, one for conducting fluid under pressure to the cylinder'67 While the other conducts discharge fluid from the cylinder 67 in a commonly known manner, are connected to a pair of

ports

73 and 74 respectively. The illustration shown in Figure 1 shows the steering or operating valve 69 'ina neutral or motionless position. The fluid under pressure entering the inlet port 75 of the steering valve 69 in the neutral position as shown is conducted to a discharge port 76 as "indicated by the arrows in Figures land 2 of the steering valve 69. When the valve sleeve element 70 is manually rotated in a clockwise direction the fluid entering the inlet port 75 is permitted to how only into the port 73 and pipe 71 to the cylinder 67 thus energizing the cylinder 67 in one direction. The discharge fluid from the cylinder 67 flows through'the pipe72 and port 74 tothe discharge port 76. Since the cylinder 67 is now energized in one direction the ground engaging wheels movecorrespondingly to'turn the vehicle and the core element 68 associated therewith moves in a clockwise direction'nntil the core element 68 reestablishes a neutral position with respect to the valve sleeve element 70 in a commonly known manner. A counterclockwise movement of the sleeve member 76 causes 'the reverse movement of the cylinder 67 in a similar manner to that just described. In other words the cylinder 67 always tends to urge the steering mechanism in a direction to reestablish the valve 69 in a neutral condition thereby permitting the fluid entering the inlet port 75 *to by-pass freely to the dis chargeport 76 while the servo-motor assembly 13 is motionless.

The second fluid motor '14 may be of any of the well known types and for purposes of this invention an ordinary two-way acting mm was selected. The second fluid motor comprises the usual housing having a movable piston 77 and associated connecting rod 78. g The ports 7 9 and '80, one being connected to each end of the motor 14, serve to introduce fluid for energizing the motor 14 in one direction While discharging fluid through the other in a commonly known manner.

The fluid circuit of this invention also includes a first control valve 11 and a second control valve 12. The first control valve 11 may consist of an ordinary well known shut-oil valve as its purpose is to control the ram 19 of the regulating valve 18. The second control valve 12 may also consist of any well known type of valve used for controlling the admission of fluid under pressure to a fluid motor and conducting the exhaust fluid therefrom. However, for simplicity, the first and

second control valves

11 and 12 may conveniently be combined into a single mechanism because both said valves are usually operated simultaneously. Referring to the drawings the combination first and second

control valve units

11 and 12 comprises the usual housing having a slidable plunger 81 movable axially as shown in Figures 1 and 2. For manually controlling the axial movement of the plunger 3'1 a lever 82 is "mounted on the control 'valve housing pivotally connected for rocking motion at 83. A rock arm 84 is rigidly connected to the lever 82, the extendin'g "end portion being pivotally connected to the .plunger $31 at 85. Thus it can be seen that rocking of the lever 82. will cause the plunger 81 to move axially with respect to its housing.

The plunger 81 is provided with annular grooves .86, 37, '83 and 89 as shown in Figure 1. Adjacent these

annular grooves

86, 87, 88 and '89 are lands "90, 91 and 92. Positioned in the housing for registration with the grooves'86, 87, 38 and '89and thel'ands 90, 91a'nd92 are

ports

93, 94, 95, 96, '97 and 98. Referring to 'theillustration in Figure 1 it may be seen that both

control valves

11 and 12 are in neutral or closed position. The port 95 is the inlet port for receiving fluid under pressure. The port 95 'is in registration with the groove 88 which groove is not in registration with'any other port a'ndhe'n'c'e no fluid flows through the "port 95 when the valves '11 and 1-2 are in the neutral position. The port '94 communicates withone side of the second fluid motor 14 by a tube 99. The land 91 is in registration with the port 94 and hence no fluid flows through the tube '99. The port 96 communicates with the other side of the second fluid motor 14 by another tube "109. The land 92 is in registration with the port 96 and hence no fluid "flows through the tube 100. Thus in the neutral position of the

control valves

11 and 12 the second fluid motor 14 is maintained under fluid lock. The port 93 is an inlet port of the first control valve 11 and since it is in registration with the land no fluid flows through the port 93.

Ports

97 and 98 are discharge .ports but since the

control valves

11 and 12 are both in neutral, Figure 1, no fluid flows therethrough.

Now referring to Figure 2 it will be seen that the lever 82 is moved in the-rightward direction causing the plunger 31 to move upwardly from the neutral positionillustrated in Figure l. The groove-87 is now in registration with the discharge port 97 and the inlet port 93 of the first control valve 11 thus permittingfluid'flow from theinlet port 93 through the groove '87 to the dischargeport-97. At the same time the groove 88 of the second control valve 12 is in registration with the fluid pressure inlet port 95 and the port 94 thus admitting fluid under .pressure to one side of the second fluid motor 14 through the tube 99 and motor port 79. Simultaneously the groove 39 is in registration with the port 96 and the discharge port 98 thereby permitting'the exhaust of fluid from the other end of the second fluid motor 14'through the -motor port 80, tube 100, port 96,groove'89to the dischargeport 98. Thus in thisrightward'positio'n of the

c'ontrol valves

11 and 12 thesecond fluidmotor is energized and provision'made for exhausting fluid from the other side of the motor 14 in a commonly known manner.

Althoughnot shown in the drawings it will be appreciated by one skilled in the art that the lever 82 may be moved in the leftward direction from the neutral position shown in Figure 1 which will cause the plunger 81 to move downwardly from the neutral position. The groove 86 then registers with the discharge port 97 and the inlet port 93 of the first control valve 11 thus permitting fluid flow from the inlet port 93 through the groove 86 to the discharge port 97. At thesame time the groove 88 of the second control valve 12 is in registration with the fluid pressureinlet port 95 and the port 96 thus'admitting fluid under pressure to' the other side of the second fluid motor through the tube 100 and themotor port 80. Simultaneously the groove 87 is in registrationwith the port 94 and the discharge port 97 thereby permitting the exhaust of fluid from the one end of the second fluid motor 14 through the motor port 79, tube 99, port 94, groove 87.to the discharge port 97. Thus in this leftward position of the lever 82 of the

control valves

11 and 12 the second fluid motor is energized in the opposite direction from that shown in Figure 2 and provision made for exhausting fluid from the one side of the motor 14 in a commonly known manner.

Each of the various elements or mechanisms have been described above and the various fluid conducting conduits interconnecting these elements to form the hydraulic circuit of this invention will now be described.

A first fluid pressure conduit 101 is communicatively connected for fluid flow to the fluid outlet means 102 of the pump 15 to the inlet port 95 of the second control valve 12 as shown in Figures 1 and 2. The first pressure conduit 101 is also communicatively connected to the inlet port 52 of the relief valve 51 and the inlet port 21 of the fluid flow dividing valve 20. A second pressure conduit 109 is connected communicatively for fluid flow to the first outlet port 22 of the divider valve and the inlet port 75 of the servo-motor assembly 13. A first fluid discharge conduit 103 communicatively connects for fluid flow the fluid inlet means 104 of the pump 15, including the reservoir 16 with the discharge port or outlet port 76 of the servo-motor assembly 13. The first discharge conduit 103 is also communicatively connected to the discharge port or outlet port 60 of the fluid pressure regulating valve 18, and the discharge or outlet port 53 of the relief valve 51. Further, the first discharge conduit 1193 is communicatively connected to the port 97 of the first and

second'control valves

11 and 12 and the'port 98 of the'second control valve 12 as shown in Figures 1' and 2. A second discharge conduit 105. communicatively connects for fluid flow the second discharge port or second outlet port 23 of the fluid flow dividing valve 20 with the inlet port 59 of pressure regulatr ing valve 18. A third discharge conduit 1% communicatively connects for fluid flow the second discharge cond nt-195 with the port 64 of the ram 19 associated with the regulatingvalve 13. At this point it will be noted thatith'ethird discharge conduit 11% is provided with a fluid flow restriction means such as an orifice 1117 for the purpose of reducing the rate of fluid flow therethrough as will hereinafter be discussed. The orifice 107 may be in the form of a reduced diameter portion of the conduit 1% or may conveniently be an adjustable valve such as a commonly'known needle-type valve. A

, fourth discharge conduit 16S communicatively connects for fluid flow the port 93 of the first control valve 11 with the third discharge conduit 106.

In the modified hydraulic circuit of this invention as shown in Figures 4 and 5 the only change from that shown in Figures 1 and 2 is that the inlet port 95 of the second control valve 12 is connected to the second discharge conduit 105 leading to the second outlet port 23 of the fluid flo'w dividing valve 20 instead of being con be appreciated that ordinary air as a fluid medium may also be used in which case, of course, the first discharge conduit 103 may be eliminated as the atmosphere itself would become a part of the circuit.

Operation In the case where a fluid circuit of this invention is used in a tractor or other vehicle it can be appreciated that the fluid pump 15 will be operated at various speeds due to the varying speed of the vehicles engine or power plant and hence the delivery of fluid by the pump 15 to the first pressure conduit 101 fluctuates accordingly. With this in mind consider first the operation of the fluid circuit of this invention in. accordance with the illustration in Figure l where the first and

second control valves

11 and 12 are both in neutral or closed position. Assume first that the pump 15 is operating at low speed and hence the fluid delivery to the first pressure conduit 101 is of a low magnitude. It will be seen that since the

control valves

11 and 12 are both closed no fluid from the first pressure conduit 101 will flow through the port 'be- 1 cause theannular groove 88 is not in registration with any other port. Similarly no. fluid flows through the fourth discharge conduit 108 because the land 90 of the plunger 31 is in registration with the port 93. Also no fluid flows from thefirst pressure conduit 101 through the relief valve 51 because, of insuificient pressure to open the valve 51. The entire flow of fluid from the. pump '15 is therefore conducted to the inlet port 21 of the divider valve 20. Since the fluid pressure at the port 21 is of low magnitude the spring 35 maintains the reciprocable valve member 36 to the extreme leftward position thus positioning the land 44 of the member 36 in complete registration with the second outlet port 23 andhence no fluid flows into the second discharge conduit 105. 7

The fluid entering the port 21 of the divider valve 20 is directed into the circumferential groove 42, thence through the channel 43 into the chamber 40, thence through the small bore or first metering passage 39 into the large bore 37, thence'through the second fluid metering passage 48 and the small or snubbing port 50 and associated groove 46, thence through a second pressure conduit 109 into the inlet port 75 of the steering valve 69 associated with the servo-motor assembly 13 and discharged through the port 76 into the first discharge conduit 1133 which in turn conducts the discharged fluid back to the pump 15 and its associated inlet means 104 through the fluid reservoir 16.

Now as the pump 15 increases its delivery of fluid to the first pressure conduit 101 the fluid flow increases at the port 21 of the divider valve 20. The increased.

fluid pressure delivered to the divider valve 20 acts on the annular surface 45 and the rear face of the reciprocable valve member 36 causing the member 36 to move rightwardly against the urging of the spring 35. The rightward movement of the member 36 is caused by the pressure differential between the groove 42 with chamber 4'?! and the opening formed by the bore 37 due to the fluid restriction occasioned by the first fluid metering passage 39. The rightward movement of the member 36 causes a progressive restriction in the flow of fluid through the second fluid metering passage 48. At the same time the circumferential groove 42 comes into part registrationwith the. second outlet port 23 of the divider duit 105.. The fluid so entering the conduit from the second outlet port 23 of the divider valve 20 is cause'the ball 57 is in abutment withthe seat 58 by the upward urging of the spring 61 'as illustrated in Figure 1.

However, the fluid in the conduit '105 is diverted into the conduit 1% and through the orific'e '107 to the port 64 and enclosure 65 of the ram 19 where the fluid acts on the piston 62 thus forcing the piston '62'and "associated work member 63 downwardly. The lower end 66 of the member63 abuts the ball 57 of'the regulating valve 18 against the upward urging of the'sp'ring 61 to unseat the ball '57 from the seat '58 thereby opening the regulating valve 13 as illustrated in Figure 1. The fluid in the conduit 105 is throttled through 'the regulator valve 18 to the first discharge conduit 103. Itwill bes'een that'the regulating valve 18 will throttle the fluid therethrough because the activity ofthe ram -19'isd'ependent upon the fluid pressure occurring in the'conduit 106.

From the above it may be appreciated that if the delivery of fluid from the pump continues to increase as'may be occasionedby suddenpressure surges the reciprocable'valve member 36 of the divider valve will reach its extreme rightward position thus closing the second fluid metering passage'48 so that the only fluid passing into the conduit 109 will'bethrou'g'h the'snubbing port 50 and associated groove 46.

As the fluid delivered by the pump 15 to the conduit 101 further increases, the ball 57 will recede further from thes'eat 58 to permit the excess fluid flowing throughcond'uit 105 to discharge through the regulator valve 18 to the discharge conduit 103. The further'movem'ent of the ball 57 downwardly occurs because the increased pressure in the

conduits

105 and 106 actuates the'ram 19 to a greater degree as heretofore discussed. When the fluid delivered by the pump 15 reaches a sufliciently high value toop'en the regulating valve 18 t'o its limit, the relief valve 51 should begin to open in throttling relation upon sure conditions which the pump '15 may deliver, the

available fluid delivered to the servo-motor assembly 13 through the conduit 109 is substantially at a constant value and therefore the servo-motorass'embl'y 13 may be operated at any time under substantially constant conditions. I

Suppose now the operator desires to use the second fluid motor '14. Referring to Figure 2 it will be seen that clockwise or rightward movement oi the lever 82 causes the plunger 81 to move upwardly. V The groove'87 now registers with

ports

93 and 97 to permitfluid to how from the fourth discharge conduit 108 through, the first control valve 11 into the first discharge conduit 103 which conduit leads back to the pump 15. At the same time the groove 88 of the second control valve 12 moves into registration with

ports

95 and 94 thereby permitting fluid under pressure from the pump 15: and'first pressure conduit 101 through the second control valve 12 and the tube 99 into one side of the second fluid motor 14. The pressure of the fluid in the motor 14 urges the piston 77 upwardly and the fluid on the other side of the motor 14 is exhausted through the tube 100 and port 9 6. The groove 89 is now in registration with

ports

96 and 98 thus permitting the'exhaustfluid fromthe motor 14 to pass through the second control 'valve 12 and discharge into'the first discharge conduit 103 which conduit leads back to the inlet means of the pump 15.

Assuming for the moment that the pump 15 is operating at idling speed and the delivery offluid to the first pressure conduit 1131 is of low magnitude such that barely enough pressure is supplied necessary to meet the requirements of the servo-motor assembly 13 including the steering valve 69 therefor. The fluid entering the port 21 of the'divider valve 20 would belinsuflicie nt to move the reciprocable'member 36 in arightward'direc- 'tion against the urging of the associated'spring 35. Thus as in the vprevious casethe fluid entering the port 21 would'be'directed'throu'gh the dividerfvalve 20 and into '69. Since the'discharge of fluid from the 'fifst pressure conduit 101 t'o'the first discharge conduit 193 thus described is without any substantial restriction, no sub stantial fluid pressure re'sults'at'the port of the second control valve 12 and hence the second fluid motor would not be energized. Suppose at this point the operator moves the steering valve 69 to actuate the cylinder 67. The'actu'ation of the servo-motor'assembly 13 would restrict the flow through the steering valve 69 into the first discharge conduit 103 which restriction causes a backpressure in the conduit 109. Since the pump 15 is operating at idling speed the delivery'of fluid in the conduit 101 would not be suiflcient to move the reciprocablemember 36 in a rightward direction and such low fluid delivery inthe conduit 1G1 is insufiicient to energize movably the second fluid motor 14 under load, the entire pressure emanating from the pump 15 is expended to move the cylinder 67 of the servo-motor assembly 13. Thus under low fluid delivery of the pump 15, the*servomotor assembly 13 has the benefit of the pumps entire output as the back-pressure upon the servo-motor assembly 13 is too low to move the motor 14.

'Now irrespective of whether the servo-motor assembly 13 is in operation or motionless if the output of the pump 15 is momentarily increased such as a pressure surge, the fluid pressure in the conduit 1G1 is'momentarily increased because the reciprocable valve member 36 of the divider valve 20 will move rightwardly to its limit thus closing the second fluid "metering passage '48 and'the only fluid flow to the servo-motor assembly '13 thereafter will be through the snubbing port 50 and its associated groove 48.

During the period of the pressure surge when the valve member 36 is at its extreme rightward limit, the pressure in the compartment within bore 37 becomes substantially'equal to the pressure in the chamber 40 and groove 42 thereby exercising no appreciable force to move the valvemember 36. Therefore spring 35 moves the valve member '36 leftward to again reestablish the second fluid metering passage 48 in throttling relation. From this it can be seen that the port 50 acts tocause a snubbing eflect on the rightward movement of the valve member 36 during the said pressure surge.

Meanwhile as the 'reciprocable valve member 36 moves rightwardly the second outlet port 23 of the divider valve 20 will progressively come into registration withthe circumferential groove 42 thereby communicating for fluid flow the first pressure conduit 191 with the second discharge conduit 105. However, the flow of fluid through the conduit 105 is restricted by the orifice 197 and the fluid which passes through the orifice 197 is promptly discharged through the fourth discharge conduit 108 which is now in communication with the first discharge conduit 103 through the first control valve 11 as hereinbefore mentioned. Thus no fluid under pressure enters'the port 64 of the ram '19 and therefore the ram 19 is not energized to open the regulator valve 18. From this it can be seen that at the higher pump delivering values the only fluid which flows through the port 21 of the divider valve20 is limited to the amount which escapes throughthe orifice 107 and the normal demand required for the servo-motor assembly 13. With the limited flow of fluid through the port 21 of the divider valve thus limited 'as above described, the excess fluid delivered'bythe pump 15 to the conduit 101 is diverted to the port 95 of the second control valve 12 and the fluid pressure is conducted through the second control valve 1.2 and the tube 99 into the port 79 thus energizing the fir st fluid motor 14 causing corresponding movement of the piston 77. It should be noted that under conditions illustrated in Figure 2 the regulator valve 18 is closed at all times since no fluid pressure is available to actuate the ram 19. Furthermore, as in the previous case if the delivery of the pump 15 causes a pressure rise in the conduit 101 above a predetermined limit the relief valve 51 opens to throttle a discharge of fluid directly into the discharge conduit 103.

' In the modified form of the invention as illustrated in Figures 4 and 5 the operation is almost identical with that described for Figures 1 and 2. The only difference is that instead of connecting the inlet port 95 of the second control valve 12 for operating the second fluid :rnotor 14 to the first pressure conduit 101, the inlet port :95 is connected to the second discharge conduit 105 which provides a distinct advantage over the circuit shown "in Figures 1 and 2.

In the previously described circuit illustrated in Figures 1 and 2, it will be noted that if the operator engages the second fluid motor'14 by operating the lever 82 associated with the first and

second control valves

11 and 12 at a time when the second fluid motor is not loaded valvef niemberfa first fluid metering passage disposed in one end portion of said valve member for communicatively connecting for fluid flow said bore with said groove, an inlet port disposed in one end portion of said housing, said inlet port being positioned for contlnuous registration with said groove, 21 source of fluid delivery or under a very light load and the pump 15 is only idling and thus delivering a pressure of low magnitude to the conduit 101, the second fluid motor 14 would move thus bleeding the fluid from the conduit 101. Under such conditions this bleeding of fluid from the conduit 101 may have some adverse effect on the fluid delivery to the servo-motor assembly 13 through the flow dividing valve 20. Although such conditions are unlikely to occur during normal operation nevertheless the remote possibility of affecting adversely the operation of the servo-motor assembly 13 may be undesirable. The modification of the circuit illustrated in Figures 4 and 5 overcomes the above described undesirable possibility because in the modified form of the invention it is necessary that the pump 15 delivers sufiicient fluid to the conduit 101 to move the reciprocable valve member 36 of the divider valve 2%) rightwardly to register the groove 42 with the second outlet port 23 to throttle fluid into the conduit 105. Since in the modified form of the invention the operation of the second fluid motor 14 and associated

control valves

11 and 12 is dependent upon fluid discharge into conduit 105 through the divider valve 20, it becomes obvious that under all conditions the servomotor assembly 13 will be fully operative provided that the pump 15 delivers suflicient fluid to meet the minimum demand of the servo-motor assembly 13. Thus under no circumstances will the second fluid motor 14 be operative unless the pump 15 delivers sulficient fluid to the divider valve 20 in excess of the demand required by the servo-motor assembly 13.

From the above it should now be apparent to those skilled in the art that the servo-motor assembly 13 is provided first with its fluid requirements under substantially constant conditions from the source of fluid delivery while substantially all of the remaining available fluid from the said source of fluid delivery is available for operating the second fluid motor 14. Of course, it should be understood that a plurality of motors may be substituted for the described second fluid motor 14 which motors may be connectable' to the fluid circuit of this invention by providing a suitable second control valve 12 to operate each additional motor.

Having thus described an embodiment of the invention, it can now be seen that the objects of the invention have been fully achieved and it must be understood that changes and modifications may be made which do not depart from thespirit of the invention as disclosed nor from the scope thereof as defined in the appended claims.

What is claimed is: a I

l. A fluid flow dividing valvetcomprising a housing, a reci rocable valve member mounted within said houscumferential groove disposed on one end portion of said connected to said inlet port, a first outlet port disposed adjacent the other end portion of said housing, a second fiuid metering passage disposed at the other end portion of said valve member, said second fluid metering passage being in registrable position for communicatively connecting for fluid flow in throttling relation said bore with said'first outlet port, a snubbing port disposed in said valve member adjacent said second fluid metering passage, said snubbing port being positioned for continuously communicating for fluid flow said bore with said first outlet port, a second outlet port disposed in said housing, said second outlet port being positioned in throttling relation with said circumferential groove of said valve member, resilient means mounted in said housing and positioned to urge said valve member in one direction for restricting fluid flow from said inlet port to said 'second' outlet port while metering said fluid flow from said inlet port to said first outlet port and said valve member being alternately movable in the other direction for throttling fluid flow from said inlet port to said first outlet port while throttling fluid flow from said inlet port to said second outlet 'port whereby the fluid flow through the first outlet port is maintained at a constant predetermined rate regardless of variation in delivery of fluid to said inlet port by said source of fluid delivery.

' '2. An hydraulic circuit comprising a fluid pump'having fluid inlet means and fluid outlet means, a first pressure conduit communicatively connected to the fluid outlet means of said pump, a fluid flow dividing valve having a fluid inlet 'port and first and second outlet ports, said first pressure conduit being communicatively connected to said inlet port of said dividing valve, said' fluid flow dividing valve having a housing, a reciprocable valve memberjmounte'd within said housing, one end of saidvalve member being positioned to form a chamber with respect to one end portion of said housing, a bore axially disposed in said valve member, a first fluid metering passage disposed in said valve member communicatively connecting for fluid flow said bore with said chamher, a circumferential groove disposed on one end portion of said valve member, said inlet port being disposed in said housing'and positioned for continuous registration with said groove, a channel disposed in said valve member, said channel being positioned to communicate for fluid'flow said groove with said chamber, said first outlet port being disposed in said housing adjacent the other end portion thereof, a second fluid metering passage disposed at'the other end of said valve member, said second fluid metering passage being inregistrable position for communicatively connecting for fluid flow in throttling relation said'bore with said first outlet port,

second outlet port. being disposed in said housing adjacent said inletiport and positioned in throttling relation with said groove of said valve member, a captive helical spring mounted intsaid housing and positioned to urgesaid valvemember in one direction, said valve member being movable in one direction for throttling fluid flow from said inlet port to said second outlet port while metering said fluid flow from said inlet port to said first outlet port and alternately being movable in the other direction for throttling fluid flow from said inlet port to said first outlet port while restricting fluid flow from said inlet port to said second outlet port, a

servo-motor assembly including a servo-motor and an operating valve therefor or" the kind which by -passes fluid from an inlet port thereof to an outlet port thereof when said servo-motor is at rest, asecond pressure conduit communicatively connecting for fluid flow said first outlet port of said fluid flow dividing valve and said inlet portot said servo-motor assembly, a first discharge conduit communicatively connecting said outlet port of said servo-motor assemblyand said fluid inlet means of said fluid pump, a ,relief valve connected to said first pressure conduit and said first discharge conduit, said relief valve being adapted to by-pass fluid under pressure from said first pressure conduit to said first discharge conduit when the fluid pressure in said first pressure conduit exceeds a predetermined value, a second discharge conduit connected communicatively for fluid flow with saidsecond outlet port of saiddividing valve, an hydraulically operable fluid flow regulating valve including an ,hydraulic actuating ram therefor communicativelyl connected for fluid flow with said first discharge conduitand said second discharge conduit, said regulating valve being adapted to regulate the rate of flow of fluid from said second discharge conduit to said first discharge conduit, a third dischargeconduit comrnunicatively connecting for fluid flow said second discharge conduit and said hydraulic ram, an orifice disposed in said third discharge conduit, said orifice being adapted to reduce theirate of flow of fluid from said second discharge conduit to said hydraulic ram, a fourth discharge conduit communicatively connected for fluid flow with said third discharge conduit at a point in said third discharge conduit between said hydraulic, ram and said orifice, a first control valve communicatively con nected in control relation with said first and fourth discharge conduits, a reversibly operable fluid motor, a first tube and a second tube cornmunicatively connected to said fluidlmotor, one of said tubes being positioned to conduct fluid under pressure to energize said fluid motor while the other tube being positioned for conducting the exhaust fluid emanating from said fluid motor, a second control valve, said second control valve being connected c'ommunicatively for fluid flow with said first pressure conduit and said first discharge conduit and said tubes, said second control valve being adapted to connect communicatively for fluid flow one of said tubes with said first pressure conduit and simultaneously connecting said other tube with said first discharge conduit, said hydraulic circuit being adapted to meter a first portion of said fluid flow from said pump to said servo-motor assembly and the excess of said fluid flow from said pump being conducted to the fluid inlet means of said pump through said dividing valve and said regulating valve When said first, and second control valves are in closed position and alternately conducting said excess fluid under pressure to said fluid motor when said first and second control valves are in open position thereby terminating fluid flow through said regulating valve.

3. An hydraulic circuit comprising a fluid pump having fluid inlet means and fluid outlet means, a first pressure conduit communicatively connected to the fluid outlet means of said pump, a fluid flow dividing valve having a fluid inlet port and first and second outlet ports, said first pressure conduit beingfcommunicatively connected to said inlet port of said dividing Valve, said fluid'flow dividing valve having a housing, a reciprocable valve member mounted within said housing, a bore axially end portion of said valvemember, said second fluid metering passagebeing iii registrable pennan s cornm'uni'catively connecting for fluid flow in throttling relation said bore with said first outlet port, a snubbing port 'disposed.adjacent said second fiuid iri'etering passage, said 7 snubbin g port being positioned for continuously communicating. for fluid flow said bore with said first outlet port, said second outlet port disposed in said housing and being positioned in throttling relation with said groove of said valve member, resilient means mounted in said housing positioned to urge said valve member in one direction for throttling fluid flow from said inlet port to said second outlet port while metering said fluid flow from said inlet port to said first outlet port and alternately being movable in the other direction for throttling fluid flow from said inlet port to said first outlet port while restricting fluid flow from said inlet port to said second outlet port, a servo-motor assembly in: cluding aservo-rnotor and an operating valve therefor of the kind which by-passes fluid from an inlet port to an outlet port thereof when said servo-motor is at rest, a second pressure conduit communicatively connecting for fluid flow said first outlet port of said fluid flow dividing valve and said inlet port o f said servo-motor assembly, a first discharge conduit communicatively connecting outlet port of said servo-motor assembly and said fluid inlet means of said fluid pump, a second discharge conduit connec'ted communicatively for fluid flow with said second outlet port of said dividing valve, an hydraulically operable fluid flow regulating valve including an hydraulic actuating ram therefore communicatively connected for fluid flow with said first discharge conduit andsaid second discharge conduit, said regulating valve being adapted to regulate the rate of flow of fluid from said second discharge conduit to said first discharge conduit, 21 third discharge conduit "communicatively connecting for fluid flow said second discharge conduit and said hydraulic ram, an orifice disposed in said third discharge conduit, said orifice being adapted to reduce the rate of flow of fluid from said second discharge conduit to said hydraulic ram, a fourth discharge conduit communicatively connected for fluid flow with said third discharge conduit at a point in said third discharge conduit between said hydraulic ram and said orifice, a first control valve communicatively connected in control relation with said first and fourth discharge conduits, a fluid motor, a tube communicatively connected to said fluid motor, said tube being positioned to conduct fluid under pressure to energize said fluid motor, a second control valve, said second control valve beingconnected in control relation communicatively for fluid flow with said first pressure conduit and said first discharge conduit and said tube, said second control valve being adapted to connect communicatively for fluid flow said tube with said first pressure conduit, said hydraulic circuit being adapted to meter a first portion of said fluid flow from said pump to said servo-motor assembly and the excess of said fluid flow from said pump being conducted to the fluid inlet means of said pump through said dividing valve and said regulating valve when said first and second control valves are in closed position and alternately conducting said excess fluid under pressure to said tube and fluid motor when said first and second control valves are in open positron thereby terminating fluid flow through said regulating valve.

4. An hydraulic circuit comprising a fluid pump having fluid inlet means and fluid outlet means, a first pressure conduit communicatively connected to the fluid outlet means of said pump, a fluid flow dividing valve having a fluid inlet port and first and second outlet ports, said first pressure conduit being communicatively connected to said inlet port of said dividing valve, said 'fluid flow dividing valve having a housing, a reciprocable valve ember mounted within said housing, one end of said valve member being positioned to form a chamber with respect to one end portion of said housing, a bore axially disposed in said valve member, a first fluid metering passage disposed in said valve member communicatively connecting for fluid flow said bore with said chamber, a circumferential groove disposed on one end portion of said valve member, said inlet port being disposed in said housing and positioned for continuous registration with said groove, a channel disposed in said valve member, said channel being positioned to communicate for fluid flow said groove with said chamber, said first outlet port being disposed in said housing adjacent the other end portion thereof,ia second fluid metering passage disposed at the other end of said valve member, said second fluid metering passage being in registrable position for communicatively connecting for fluid flow in throttling relation said bore With said first outlet port, a snubbingport disposed in said valve member adjacent said second fluid metering passage, said snubbing port being positioned for continuously communicating for fluid flow said bore with said first outlet port, said second outlet port being disposed in said housing adjacent saidinlet port and positioned in throttling relation with said groove of said valve member, a captive helical spring mounted in said housing and positioned to urge said valve member in one direction, said valve member being movable in one direction for throttling fluid flow from said inlet port to said second outlet port While metering said fluid flow from said inlet port to said first outlet port and alternately being movable in the other direction for throttling fluid flow from said inlet port to said first outlet port while restricting fluid flow from said inlet port to said second outlet port, a servo-motor assembly including a servomotor and an operating valve therefor of the kind which by-passes fluid from an inlet port thereof to an outlet port thereof when said servo-motor is at rest, a second pressure conduit communicatively connecting for fluid flow said'first outlet port of said fluid flow dividing valve and said inlet port of said servo-motor assembly, a first discharge conduit communicatively connecting said outlet port of said servo-motor assembly and said fluid inlet means of said fluid pump, a relief valve connected to said first pressure conduit and said first discharge conduit, said relief valve being adapted to by-pass fluid under pressure from said first pressure conduit to said first discharge conduit when the fluid pressure in said first pressure conduit exceeds a predetermined value, a second discharge conduit connected communicatively for fluid flow with said second outlet port of said dividing valve, an hydraulically operable fluid flow regulating valve includ ing an hydraulic actuating ram therefor communicatively connected for fluid flow with said first discharge conduit and said second discharge conduit, said regulating valve being adapted to regulate the rate of flow of fluid from said second discharge conduit to said first discharge conduit, a third discharge conduit communicatively connecting for fluid flow said second discharge conduit and said hydraulic ram, an orifice disposed in said third discharge conduit, said orifice being adapted to reduce the rate of flow of fluid from said second discharge conduit to said hydraulic ram, a fourth discharge conduit com municatively connected for fluid flow with said third discharge conduit at a point in said third discharge conduit between said hydraulic ram and said orifice, a first control valve communicatively connected in control relation with said first and fourth discharge conduits, a reversibly operable fluid motor, a first tube and a second tube cornmunicatively connected to said fluid motor, one 'of said tubes being positioned to conduct fluid under pressure to energize said fluid motor while the other tube being positioned for conducting the exhaust fluid emanating from said fluid motor, a second control valve, said sec ond control valve being connected communicatively for fluid flow with said second discharge conduit and said first discharge conduit and said tubes, said second control valvetbeing adapted to connect communicatively for fluid flow one of said tubes with said second discharge conduit and simultaneously connecting said other tube with said first discharge conduit, said hydraulic circuit being adapted to meter a first portion of said fluid flow from said pump to said servo-motor assembly and the excess of said fluid flow from said pump being conducted to the fluid inlet means of said pump through said dividing valve and said regulating valve when said first and second control valves are in closed position and alternately conducting said excess fluid flow to said fluid motor when said first and second control valves are in open position thereby terminating fluid flow through said regulating valve.

'5. An hydraulic circuit comprising a fluid pump having fluid inlet means and fluid outlet means, a first pressure conduit communicatively connected to the fluid outlet means of said pump, a fluid flow dividing valve having a fluid inlet port and first and second outlet ports, said first pressure conduit being communicatively connected to said inlet port of said dividing valve, said fluid flow dividing valve having a housing, a reciprocable valve member mounted within said housing, a bore axiallydisposed in said valve member, a circumferential groove disposed on one end portion of said valve member, a first fluid metering passage disposed in said valve member positioned for communicatively connecting for fluid flow said bore with said groove, said inlet port being positioned in one end portion of said housing for continuous registration with said groove, said first outlet port disposed in the other end portion of said housing, a second fluid metering passage disposed at the other end portion of said valve member, said second fluid metering passage being in registrable position for communicatively connecting for fluid flow in throttling relation said bore with said first outlet p0rt, a snubbing port disposed adjacent said second fluid metering passage, said snubbing port being positioned for continuously communicating for fluid flow said bore with said first outlet port, said second outlet port disposed in said housing and being positioned in throttling relation with said groove of said valve member, resilient means mounted in said housing positioned to urge said valve member in one direction for throttling fluid flow from said inlet port to said second outlet port while metering said fluid flow from said inlet port to said first outlet port and alternately being movable in the other direction for throttling fluid flow from said inlet port to said first outlet port while restricting fluid flow from said inlet port to said second outlet port, a servo-motor assembly including a servo-motor and an operating valve therefor of the kind which by-passes fluid from an inlet port to an outlet port thereof when said servo-motor is at rest, a second pressure conduit communicatively connecting for fluid flow said first outlet port of said fluid flow dividing valve and said inlet port 'of said servo-motor assembly, a first discharge conduit communicatively connecting said outlet port of said servo-motor assembly and said fluid inlet means of said fluid pump, a second discharge conduit connected communicatively for fluid flow with said second outlet port of said dividing valve, an hydraulically operable fluid flow regulating valve including an hydraulic actuating ram therefor communicatively connected for fluid flow with said first discharge conduit and said second discharge conduit, said regulating valve being adapted to regulate the rate of flow of fluid from said second discharge conduit to said first discharge conduit, a third discharge conduit communicatively connecting for fluid flow said second discharge conduit and said hydraulic ram, an orifice disposed in said third discharge conduit, said orifice being adapted to reduce the rate of flow of fluid from a and said orifice, a first control valve communicatively connected in control relation with said first and fourth dis charge conduits, a fluid motor, a tube communicatively connected to said fluid motor, said tube being positioned to condut fluid under pressure to energize said fluid motor, a second control valve, said second control valve being connected in control relation communicatively for fluid flow with said second discharge conduit and said first discharge conduit and said tube, said second control valve being adapted to connect communicatively for fluid flow said tube with said second discharge conduit, said hydraulic circuit being adapted to meter a first portion of said fluid flow from said pump to said servo-motor assembly and the excess of said fluid flow from said pump being conducted to the fluid inlet means of said pump through said dividing valve and said regulating valve when said first and second control valves are in closed position and alternately conducting said excess fluid flow to said tube and fluid motor when said first and second control valves are in open position thereby terminating fluid flow through said regulating valve.

6. A fluid system for dividing the flow of fluid under limited pressure from a source of variable rate fluid delivery having fluid return means comprising a servo-motor assembly including a servo-motor and control means therefor, a second fluid motor, said servo-motor assembly being of the kind which by-passes fluid from an inlet port thereof to an outlet port thereof communicatively connected to said fluid return means when said servo-motor is at rest, a fluid flow dividing mechanism having a flow dividing valve communicatively connected to a fluid pressure regulating valve, said fluid flow dividing valve being communicatively connected to said source of fluid delivery and said servo-motor assembly, said regulating valve being communicatively connected to said fluid return means, a first control valve communicatively connected in control relation to said regulating valve and said fluid return means, a second control valve communicatively connectable in control relation with said second fluid motor and said source of fluid delivery and said fluid return means, said fluid flow dividing mechanism being adapted to meter a first portion of fluid flow at substantially constant rate from said source of fluid delivery to said servo-motor assembly and diverting the excess portion of said fluid flow over and above said first portion to said second fluid motor when said first and second control valves are in open position and alternately discharging to said return means said excess portion of fluid flow when said first and second control valves are in closed position.

References Cited in the file of this patent UNITED STATES PATENTS 2,363,179 Harrington Nov. 21, 1944 2,603,065 Sarto July 15, 1952 2,674,092 Gardiner Apr. 6, 1954 2,708,344 Greer May 17, 1955 2,737,196 Eames Mar. 6, 1956