US3870255A

US3870255A - Hoist drive system

Info

Publication number: US3870255A
Application number: US343128A
Authority: US
Inventors: Harold Edminston Lemont
Original assignee: Hughes Tool Co
Current assignee: Boeing Co
Priority date: 1970-07-07
Filing date: 1973-03-20
Publication date: 1975-03-11
Anticipated expiration: 1992-03-11

Abstract

A hoist on a hover-type aircraft is actuated through differential gearing by hydraulic motor means which, in turn, is actuated by a power driven variable displacement hydraulic pump. A hoist controller incorporating computer circuits controls the hoist speed by varying the displacement of the pump and employs a servo loop to cause the hoist to seek a speed that corresponds to the instant position of a manually operable speed control lever. A thumb-operated three-position switch on the control lever actuates solenoid valves to control energization of the hoist drum and its direction of rotation.

Description

o 1 Unite States atent 11 1 1111 3,870,255

Lemont Mar. 11, 1975 [54] HOIST DRIVE SYSTEM 3,240,474 3/1966 Garnier 254/173 R 3,249,336 5/1966 Brown et al. 254/150 FH [75] Edmmsfon Lemon" 3,309,064 3/1967 Muller et a1. 254/173 R Calabasasv Callf- 3,352,152 11/1967 Abraham 254/150 FH 3,380,545 4/1968 Kcmpcr 188/72 [73] Assrgnee. Hughes Tool Co., Culver Clty, Callf. $389,880 (/1968 Ferguson u 244,137 [22] Filed: Mar. 20, 1973 3,464,528 9/1969 Mork ct a1. 254/187 R 21 A I. No.: 343,128 1 pp Primary Examiner-Trygve M. Blix Related pp Data Assistant Examiner-Gregory W. OConnor [63] Continuation of Ser. No. 53,479, July 7, 1970, A torn y, g n -George F. Smyth abandoned.

[52] U.S. Cl..... 244/137, 254/150 FH [57} ABSTRACT [51] Int. Cl. B64c 1/22 A hoist n a hover-type aircraft is actuated through [58] Field of Search, 254/150 F11, 172, 173 R, differential gearing by hydraulic motor means which,

4/l87 R, 187 A; 244/137; 188/178, 72 in turn, is actuated by a power driven variable displacement hydraulic pump. A hoist controller incor- [56] Referen Cit d porating computer circuits controls the hoist speed by UNITED STATES PATENTS varying the displacement of the pump and employs a 1,953,151 4/1934 0.111111 254/187 R Servo loop to the hoisgo Seek a Speed that 964 762 (H934 Kinzbach 254N150 responds to the instant posmon of a manually opera- Crane I I Speed COnIIOl lever. A thumb-Operated three- 9,1949 Cotton I I 254/l73 R position switch on the control lever actuates solenoid 2,827,763 3/1953 Govan er 1 254 172 valves to control energization of the hoist drum and its 3,032,293 5/1962 Fonden et 111.. 254/1731R direction Of rotation. 3,107,399 10/1963 Henneman..... 254/187 R 3.189.195 6/1965 Fox et a1. 254/173 R 5 ClalmS, 9 Drawing Flgures J 73-; 2 J33??? g Swim Z) Ji /m l 7 J07 Mar m Kali e /2/2014! 4 7 we 4 j37 x 0/8/101 6mm? 76m. ,5 JEwH 1699/) Val/e 1 7 0/5/2074 155w m y A80 lwso/ 7 23:;

J Pilaf/Mar 67 14 2 ZZZ/{'6 giiig Qm/rd/er 104 4 Mi 16; 1190 g; 192

' H 8 E- pwfllo l a/ve 1167 172 '6 ram/fi ,g 152 e "f gar j Kali e l e 1:}: 002ml y f PATENTEDHARI 1 s 1 3'. 870.255

SHEET 3 [IF 4 107 f 7 I A E 65 rig? 20,40 fl MM smM 1544010;

v rmeA/E st l-IOIST DRIVE SYSTEM RELATED APPLICATION This is a continuation of application Ser. No. 53,479, filed July 7, 1970, now abandoned.

BACKGROUND OF THE INVENTION To provide a hover-type aircraft such as a helicopter with a cargo hoist having a capacity in the range of twelve to fifty tons involves consideration for a number of requisites including: reliability; efficiency; speed of operation; versatility to meet emergencies; safety with emphasis on fail-safe components; low heat generation; smooth application of power; and, of primary importance, minimum overall weight. Numerous problems are involved with a wide range of choice of possible solutions by mechanical, electrical, hydraulic and pneumatic means.

The selection of a tension member to support the hoist loads is important in that the minimum possible bend radius for a particular tension member determines the size and type of the hoist system. A directwound -ton capacity wire cable requires approximately a LS-inch-diameter cable together with an extremely large drum and the cable cannot be laid over itself on the drum because crushing and destruction of the cable would occur.

A practical method of speed reduction is a problem because conventional methods of speed reduction are unsuitable for various reasons. For example, planetary gearing for converting a 12,000 rpm input into a 60- foot per minute lifting speed would require four to six stages of gearing and as many as 64 gears with consequent excessive weight and low efficiency as well as excessive heat generation under continuous operation. Employing a harmonic drive system for speed reduction would result in low efficiency, excessive friction and high heat generation. Both a cam drive system and a worm gear drive system have in general the same difficiencies.

With reference to the provision of a hoist brake, the requisites are: effective dissipation of load-lowering energy; effective control of lowering speeds; and ability to hold a suspended load. The use of an electrical system as a brake would make possible recovery of energy in the lowering of loads but efficient storage of the recovered energy is a problem and such a system would necessarily be of excessive size. Pneumatic and hydraulic brakes are susceptible to leakage and, moreover, may slip under heavy loads.

The broad object of the present invention is to provide optimum solutions to the various problems to arrive at the design of a practical hoist drive system.

SUMMARY OF THE INVENTION A multiple-strand load-supporting tape is wound on a hoist drum that is driven by speed-reducing differential gearing inside the drum. A hydraulic pump actuates two hydraulic motors which, in turn, drive in opposite respects two input gear trains of the differential gearing, the two input gear trains having slightly different gear ratios with the output speed determined by the differential between the two ratios.

The hoist drive responds to changes in position of a manually operable speed control lever and to manipu lations of a thumb switch on the lever having a stop position, a raise position and a lower position. A

incorporates appropriate computer circuits and regulates the hoist speed by varying the displacement of the hydraulic pump. The speed control lever is freely movable independently of the controller but the hoist controller responds to changes in position of the speed control lever and employs a servo loop to regulate the hoist speed in accord with the adjustment of the speed control lever.

A solenoid-actuated main supply valve responds to the thumb switch to control the flow of hydraulic fluid from the hydraulic pump to the hydraulic motor means to start and stop the hoist drum and a pair of solenoidactuated 3-way valves respond to the thumb switch to control the direction of the hydraulic flow through the hydraulic motor means to determine the direction of rotation of the hoist drum. A third solenoid-actuated valve that responds to the thumb switch functions as a pilot valve to control the hoist brake. The pilot valve that is in series with a servo valve which is part of a servo loop that regulates the brake pressure to control the rate of rotation of the brake drum when the brake drum is actuated by the weight of a descending load.

When the hoist drum is rotated in reverse by the gravity pull of a descending load, the hydraulic motor means is also operated in reverse and is permitted to function temporarily as a pump for reverse flow of the hydraulic actuating fluid. A feature of the invention is that whenever gravity-actuation of the hoist drum causes the hoist brake to overheat, a braketemperature sensor causes the hoist controller to operate a solenoid-actuated throttle valve which restricts the reverse flow of the hydraulic fluid from the hydraulic motor means and thus provides an additional hoistretarding force to reduce the the load on the hoist brake.

Whether or not a load is imposed on the hoist tape is signalled to the controller and a tape-length potentiometer signals the approach of the tape to either of its two opposite limits to permit the controller to decelerate the hoist drum limit switches serve to stop the hoist drum whenever the two opposite limits of the'hoist tape are reached.

A further feature of the invention is provision of means for rapid lowering of the hoist tape when it is not under load. For this purpose a special control component such as a push button is effective to disengage clutch means to release the hoist drum for free rotation and the special control component is further effective to cause a pair of motor-driven rollers to engage the hoist tape and pull it rapidly downwardly.

A pressure transducer that senses the pressure of the brake fluid that keeps the hoist brake released in opposition to the hoist brake springs serves the purpose of causing the hoist controller to stop the hoist drum in the event that failure of the brake fluid system permits the hoist brake to be applied while the hydraulic motor means is driving the hoist drum.

The various features and advantages of the invention may be understood from the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, which are to be regarded as merely illustrative:

FIG; 1 is a view partly in side elevation and partly in section showing the hoist drum and associated working parts;

FIG. 2 is a view partly in end elevation and partly in section also showing the hoist drum and associated components;

FIG. 3 is a fragmentary diagrammatic view of gear members of the differential gearing indicating how speed reduction is accomplished;

FIG. 4 is a diagram of the hydraulic system that is employed to control the hoist drum;

FIG. 5 is a block diagram of a control system that may be employed; and

FIGS. 6, 7, 8 and 9 are fragmentary perspective views of various constructions of the hoist tape that may be employed.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION In the assembly shown in FIGS. 1 and 2, the hoist drum is of hollow construction with a cylindrical inner circumferential wall 20, two opposite side flanges 22 and a side wall 24 that functions as a brake disk in cooperation with a pack of thin annular brake disks 25. A relatively wide tape 26 to raise and lower loads is wound into a coil 28 on the hoist drum with the inner end ofthe tape anchored to the hoist drum by a suitable retention clamp 30 as shown in FIG. 2. The downwardly extending tape 26 is confined edgewise between a pair of spaced smooth guides 32 and is confined across its thickness by a pair of cooperating guide rollers 34. As the tape approaches the guide rollers 34 it passes through a pyrotechnic tape cutter 35 of a well known type that may be employed to sever the tape in an emergency. As the tape issues from the pair of guide rollers 34 the opposite faces of the tape are contacted by a pair of suitable wiper elements 36.

While the tape 26 may be a solid flexible web, it is highly advantageous to employ a multiple-element tape whichmay be constructed, for example, as shown in any one of FIGS. 6 9. The tape shown in FIG. 6 comprises a plurality of wires 38 of round cross section bonded together in side-by-side relationship and in like manner the tape shown in FIG. 7 comprises wires 40 of rectangular cross-sectional configuration bonded together. In both of these constructions, the wires may be music wires.

The tapes shown in FIGS. 8 and 9 are laminated structures made of composite material. The composite material may comprise, for example, boron filaments in the form of wiskers or carbon filaments in the form of wiskers, the wiskers being embedded in a suitable flexible material such a suitable epoxy with all of the filaments oriented longitudinally of the tape. The tape shown in FIG. 8 has a plurality of full-width laminations 42 and the tape shown in FIG. 9 is of similar construction but comprises a plurality of laminated members 44 bonded together in side-by-side relationship.

The hoist drum is fixedly mounted on a tubular drive shaft or axle 45 that is journalled by bearings 46 on a support structure 48 which, in turn, is mounted by bearings 50 (FIG. 2) on a pair of spaced coaxial support sleeves 52. The support sleeves 52 are carried by corresponding pairs of bracket arms 54 that are rigidly mounted on the frame structure of the aircraft. A slip ring assembly 55 at one end of the tubular axle 45 'makes possible circuits incorporated in the tape structure for various purposes including actuation of loadengaging devices at the end of the tape.

For the purpose of driving the tubular axle 45, the tubular axle has four radial spokes 56 to function as a planet gear carrier with bevelled planet gears 58 mounted on the four spokes respectively by bearings 60. In a well known manner the opposite sides of the bevelled planet gears 58 mesh with the output teeth of a pair of bevelled differential gears, which for convenience may be termed a left hand differential gear 62 and a right hand differential gear 64, each of which is rotatably mounted on the tubular axle 45 by a corresponding bearing 65.

Although a single hydraulic motor may be employed to actuate the hoist'drum, the present embodiment of the invention advantageously employs a pair of duplicate hydraulic motors 66 which are mounted on the left side of the hoist drum assembly, one of the two hydraulic motors being shown in phantom in FIG. 1. Each of the two hydraulic motors 66 has an output shaft 68 which carries a drive pinion 70 in mesh with the input teeth 72 of the left hand differential gear 62, the input teeth being formed by a ring that is anchored to the outer side of the left hand differential gear by suitable screws 74.

United with the right hand differential gear 64 to function as a part thereof is a gear housing 75 inside the hoist drum which gear housing encloses the orbiting planet gears 58. The gear housing 75 extends leftward to the region adjacent the left hand differential gear 62 where the gear housing is provided with external input teeth 76. The input teeth 76 are formed by a ring that is anchored to the left side of the gear housing 75 by suitable screws 78. Each of the previously mentioned drive pinions 70 on the output shafts 68 respectively of the two hydraulic motors 66 is in mesh not only with the input teeth 72 of the left hand differential gear 62 but is also in mesh with a reversing idler gear 80 which, in turn, is in mesh with the input teeth 76 of the right hand differential gear 64.

FIG. 3 shows schematically how the reversing idler gear 80 meshes both with the drive pinion 70 and the input teeth 76 of the right hand differential gear 64. FIG. 3 also shows that the diameter of the input teeth 72 of the left hand differential gear 62 are on a diameter which is slightly less than the diameter of the input teeth 76 of the right hand differential gear 64. Thus each of the two hydraulic motors 66 drives two input gear trains to actuate the planet gears 58, one input gear train comprising a drive pinion 70 and the left hand differential gear 62, the other input gear train comprising a drive pinion 70, a reversing idler gear 80 and the right hand differential gear 64. Since the two

differential gears

62 and 64 are driven in opposite directions, the rate of rotation imparted to the spokes 56 that carry the planet gears 58 is determined by the differential between the two diameters, the resulting speed reduction being such that the tape travels at approximately 60 feet per minute.

The previously mentioned pack of annular brake disks 25 is backed up by a pressure ring 82 which is acted upon by a plurality of brake-loading springs 84 of sufficient strength to immobilize the hoist drum under the heaviest contemplated load. For the purpose of releasing the brake, a plurality of radially arranged brakerelease levers 85 are fulcrumed at their outer ends by links 86 which are pivotally connected to the adjacent support structure 48. Each of the brake-release levers 85 is connected by a pivot 88 to the outer end of a corresponding stud 90 that is fixedly mounted on the pressure ring 82. The inner input ends of the brake release levers 85 seat against a fitting 92 on the right end of an axial operating rod 94 that extends through the tubular axle 45. The left end of the operating rod 94 is fixedly connected to a piston 95 in a hydraulic brake-release cylinder 96. This arrangement permits the hoist brake to be normally applied by the series of springs 84 and to be released when desired by energization of the brake-release cylinder 96 by remote control. Preferably a bath of oil for the brake is confined by means including a removable cover 98 that is provided with a suitable oil-level sight glass 100.

HYDRAULIC SYSTEM The hydraulic system that is shown diagrammatically in FIG. 4 includes a hydraulic fluid reservoir 102 and a variable displacement hydraulic pump 104 that is actuated by the aircraft power plant. The hydraulic pump 104 may be of the axial piston type and in a well known manner the displacement control 105 of the pump may consist essentially of a swash plate (not shown) which may be tilted through a range of angles to vary the length of the piston stroke and thereby vary the rate of fluid output by the pump. The intake side of the hydraulic pump 104 is connected to the fluid reservoir 102 by a supply line 106 and the output side of the pump is connected to a solenoid-actuated main supply valve 107 which controls energization of the two hydraulic motors 66.

The main supply valve 107 is connected by a line 108 to a solenoid-actuated 3-way valve designated A, and is connected by a line 110 to a similar solenoidactuated 3-way valve, designated B. The 3-way valve B is connected to the reservoir 102 by a line 112 and the 3-way valve A is connected to the reservoir by a line 114 that is provided with a solenoid-actuated throttle valve 116 which may be operated whenever it is desirable to restrict the return flow from valve A. The 3-way control valve A is connected to one side of each of the two hydraulic motors 66 by a line 1 18 and in like manner, the 3-way valve B is connected to the other side of each of the two motors by a line 120.

In this particular embodiment of the invention each of the two hydraulic motors 66 is releasably connected to the corresponding motor shaft 68 by a suitable spring-actuated clutch 122 that may be electrically disengaged when desired by remote control.

When the solenoids of the two valves A and B are deenergized, the input of thetwo hydraulic motors 66 is through valve A and the output from the motors is through valve B with the two motors rotating in the direction to raise the tape 26. When the solenoid valves A and B are energized, the input to the two motors is through valve B and the output from the two motors is through valve A and throttle valve 116 to cause the two motors to rotate in the direction to lower the tape. During any time period in which operation of the hoist drum may be required, the pump 104 is operated continuously and when the main supply valve 107 is closed, the fluid discharge by the pump is returned to the reservoir 102-by a line 124 that is provided with a relief valve 125 in a well known manner.

Pressurized hydraulic fluid direct from the pump 104 is available through a supply line 126 to control the previously described hoist drum brake, which brake is designated 128 in FIG. 4. The supply line 126 is connected to the previously mentioned brake-release cylinder 96 through a solenoid-actuated pilot valve 130 in series with an electrically modulated servo valve 132. The servo valve 132 is connected to the fluid reservoir 102 by a return line 134 and is capable of varying the pressure in the brake-release cylinder 96 by varying the rate at which the hydraulic fluid is bypassed to the reservoir through the return line 134. A pressure transducer 135 detects changes in the fluid pressure in the brake-release cylinder 96.

An excessive rise in brake temperature operates a thermally responsive switch 136 and changes in the load that is carried by the tape 26 are detected by a load sensor 138 which may be a strain gage on the support structure 48 for the hoist drum. A tape-length detector 140 may be in the form of a potentiometer that is operatively connected to the tape and a speed sensor 142 for sensing the approximate rate of travel of the tape may be operatively connected to any movable part that is associated with the hoist drum.

CONTROL SYSTEM In the control system that is shown diagrammatically in FIG. 5, a manually operable speed control lever 144 that is swingable about an axis 145 has a knob or handle 146 which carries a thumb switch 148. The thumb switch 148 has a stop position, a raise position and a lower position and is spring-biased to seek the stop position. The speed control lever 144 is operatively associated with a hoist controller 150, as indicated by a dotted line 152, but the speed control lever is freely movable manually independently of the controller.

The 3-position thumb switch 148 is connected to the positive side of a circuit as indicated and is connected to the hoist controller 150 by a pair of leads 154 and 155. The previouslymentioned brake temperature sensor 136, load sensor 138 and tape-length potentiometer 140 are also connected to the hoist controller 150 by corresponding

leads

156, 157 and 158. The hoist controller 150 is connected to the solenoids of main supply valve A, valve B, and brake pilot valve 130 by corresponding leads 160 163.

The solenoids of valve A, valve B and brake pilot valve 130 are connected to ground as indicated. The solenoid of main supply valve 107, however, is connected to ground through three normally closed switches in series, namely, an up limit switch 164 that opens when the tape is pulled up to its limit, a down limit switch 165 that opens whenever the tape is extended downward to its limit and the previously mentioned pressure responsive switch 135 that opens whenever the hydraulic pressure fails in the brake release cylinder 96.

The controller 150 incorporates suitable computer circuits and controls a power amplifier 166 which regulates a 4-way valve 168. The 4-way valve 168, in turn, controls the flow of hydraulic fluid to and from a hydraulic power cylinder 170, that has a piston (not shown) operatively connected to the previously mentioned pump-displacement control 105. It is apparent in FIG. that the speed sensor 142 completes a servo loop to make it possible for the pump-displacement control 105 to be adjusted automatically for whatever speed of the hoist drum is indicated by the instant position of the speed control lever 144.

The hoist controller 150 is also connected to a power amplifier 172 that controls the adjustment of the brake servo valve 132. Thus the speed sensor 142 also completes a second servo loop by means of which the hoist controller adjusts the brake pressure to cause the speed of rotation of the hoist drum to correspond to the position ofthe speed control lever 144 when the hoist drum is driven by the weight of a descending load without input of hydraulic power.

OPERATION Unreeling the Unloaded Tape at a Normal Rate The pilot positions the speed control lever 145 for the desired hoist speed and then moves the thumb switch 148 to its lower position and holds it there in opposition to its spring bias. The inputs to hoist controller 150 from the thumb switch 148 together with a no load input from the load sensor 138 results in signal outputs from the hoist controller that energize the solenoids of the main supply valve 107, the 3-way valve A, the 3-way valve B, and the brake pilot valve 130. The dual hydraulic motors 66 operate in reverse and the brake 96 is released.

When the hoist drum accelerates to the speed that is represented by the selected position of the speed control lever 144, a feed back signal from the speed sensor 142 causes the supply pump displacement control 105 to hold at that level of fluid flow. When the desired length of tape has been lowered, the pilot releases the thumb switch 148 to permit it to return to its stop position. The resulting deenergization of the solenoids for the four valves 107, A, B, and 130 stops the two bydraulic motors and applies the hoist brake to lock the tape at the desired length. The rate at which the tape is lowered may be varied during the unreeling of the tape by changing the position of the speed control lever 144. If the pilot inadvertently fails to release the thumb switch 148 before the drum unreels all of the tape, the down limit switch 165 opens to deenergize the solenoid of the main supply valve 107 to stop the two hydraulic motors.

Unreeling the Unloaded Tape Rapidly in an Emergency At the normal rate of 60 feet per minute, lowering 150 feet of the tape requires 2.5 minutes but in combat or in other emergency situations it should be possible to lower the full length of tape in 5 to seconds. For this purpose a control 178, which may be a push button switch, is connected to the hoist controller 150 by a lead 180 and may be actuated to cause the hoist controller 150 to energize a circuit 174. The circuit 174 disengages the two previously mentioned clutches 122 and in addition energizes a solenoid valve 175 of a small hydraulic cylinder 176 as well as solenoid valves 178 of two small hydraulic motors 180. The hydraulic cylinder 176 presses two normally retracted rollers 182 against opposite faces of the tape 26 and the two bydraulic motors drive the two rollers respectively to unreel the tape at the desired speed.

Raising a Load while Hovering After the hoist hook on the end of the tape has been attached to the load and after the speed control lever 144 has been set for the desired hoist speed, the pilot moves the thumb switch 148 to its raise position. The computer circuits of the controller 150 send out signals to energize the solenoids of the main valve 107 and the brake pilot valve 130. The 3-way valves A and B remain in their deenergized positions to cause the hydraulic fluid to flow to the two motors through the 3-way valve A and to return through the 3-way valve B for rotation of the hoist drum in the direction to raise the tape. As the tapes snugs up and picks up the load slowly, the stability of the helicopter under the load is quickly checked. If the stability is satisfactory, the speed of upward travel of the tape is increased as desired by resetting the speed control lever 144. When the desired speed of upward travel of the tape is attained, the feed back signal from the speed sensor 142 causes the pump displacement control to hold at that level of fluid flow. If the helicopter and the load are not sufficiently stable when the load is initially transferred to the tape, the pilot may shift the thumb switch 148 from raised to lower and return the load to its initial position.

When the tape lifts the load to the desired height, the travel of the tape may be stopped by releasing the thumb switch 148 with consequent closing of the main supply valve 107 to stop the hydraulic motors and also with consequent deenergization of the solenoid of the brake pilot valve 130 to apply the hoist drum brake. If the pilot inadvertantly fails to release the thumb switch 148 before the tape is completely reeled in, the up limit switch 164 opens to deenergize the solenoid of the main supply valve 107 to stop the two hydraulic motors.

Lowering a Load while Hovering A pilot sets the speed control lever 144 for the desired hoist speed and moves the thumb switch 148 to its lower position. The consequent inputs to the controller 150 together with a loaded input from the load sensor 138 result in output signals from the controller which energize the solenoids of 3-way valve A and brake pilot valve 130. The solenoid of the main supply valve 107 is not energized because instead of the motors 66 being energized by the pump 104 to lower the tape under load, it is contemplated that the two motors will be operated in reverse as pump means to have a retarding effect of the descending load.

Since 3-way valve A is energized and 3-way valve B is deenergized, hydraulic fluid from the reservoir 102 flows to the two motors through line 112, 3-way valve B and line with return flow from the motors to the reservoir through line 18, 3-way valve A, throttle valve 116 and line 114. When a load is being lowered in this manner the throttle valve 116 is normally open and the brake 128 is applied to whatever degree is necessary for complete control of the descending load. The speed sensor 142 and the power amplifier 172 are part of a servo loop by means of which the controller 150 regulates the rate at which the load is lowered under gravity in accord with the selected position of the speed control lever 144. The load may be stopped at any height by releasing the thumb switch 148 with consequent deenergization of the solenoid of brake pilot valve for application of the hoist drum brake and with consequent deenergization of the solenoid of 3-way valve A to cut off oil circulation through the two motors.

If the hoist drum brake 128 becomes too hot during the gravity descent of the load, the brake temperature sensor 136 causes the hoist controller 150 to operate the throttle valve 116 to restrict the rate of discharge flow from the two motors and thus greatly increase the braking effect of the two motors.

My description in specific detail of the presently preferred embodiment of the invention will suggest various changes, substitutions and other departures from my disclosure within the spirit and scope of the appended claims.

I claim:

1. In a hoist system for lifting and lowering loads from a hovering type aircraft, the combination of:

an elongated flexible tension member to support loads;

rotary means on the aircraft in engagement with the tension member for extension and retraction thereof;

fluid motor means connected to said rotary means for actuation thereof;

fluid pump means;

means connecting the pump means to the motor means for flow of fluid thereto,

said connecting means including reversible means operable in one respect for flow of fluid in one direction through the fluid motor means to cause the tension member to travel in one direction and operable in the opposite respect for flow of fluid in the opposite direction to cause the tension member to travel in the opposite direction;

means for remote operation of said reversible means in its opposite respects selectively to control the direction of travel of the tension member;

means to vary the displacement of one of said pump means and said fluid motor means to control the rate of travel of the flexible member;

said motor means being constructed to act as temporary pump means on said fluid with the temporary pump means actuated by the weight of a descending load on the tension member;

means to restrict the fluid discharge of the temporary pump means to retard the lowering of the load and said restricting means is normally ineffective; brake means to retard the lowering of the load; and means to make the restricting means effective in response to rise in temperature of the brake means.

2. In a hoist system for lifting and lowering loads from a hovering type aircraft, the combination of:

an elongated flexible tension member to support loads;

fluid motor means connected to said rotary means for actuation thereof; fluid pump means to actuate the fluid motor means; solenoid-actuated supply valve means between the pump means and the motor means operable to permit the pump means to actuate the motor means;

solenoid actuated directional valve means between the pump means and the motor means to control the direction of rotation of the motor means;

means to vary the displacement of one of said pump means and said motor means to vary the rate of operation of the motor means;

a hoist controller;

a manually operable speed control member movable independently of the controller through a range of positions representing a range of speeds of the rotary member;

means to indicate to the hoist controller the position of said control member;

a servo loop including means responsive to the hoist controller to regulate said displacement means and including means to sense the speed of the rotary means to cause changes in speed of the rotary means to substantiallyfollow changes in position of the speed control member;

manually operable actuation control means having'a raise" position, a lower position and a "stop position,

said-supply valve means and directional valve means beingresponsive to said manually operable control; and

said actuation control being finger-actuated switch means mounted on said manually operable speed control member.

3. A hoist system for lifting and hovering a load from an aircraft, including:

an elongated flexible tension member to support the load;

rotary means on the aircraft engaging the tension member for extension and retraction thereof;

at least one brake disk releasably engaging the rotary means;

a pressure member engaging at least one of the brake disks on the side thereof remote from the rotary means;

biasing means engaging the pressure member normally to maintain the disks in an engaging relationship with the rotary means so that the braking means normally inhibits the rotation of the rotary means;

lever means engaging the pressure member and operative to move the pressure member outwardly to oppose the bias of said biasing means so that the brake disks engage the rotary member;

operating rod means extending axially of said rotary means;

a plurality of first levers pivotally mounted on the aircraft;

a plurality of second levers linking the first levers with the pressure member; and

the operating rod being movable in a first axial direction to engage the first levers whereby further movement of the operating rod in the first direction opposes the bias of the pressure member.

4. A hoist as in claim 3 wherein the braking means includes a supporting member having a substantially fixed relationship with the aircraft for supporting the rotary means; and

a bath of oil confined by the supporting member to provide lubrication for the braking means.

5. In a hoist system for lifting and lowering loads'from a hovering type aircraft, the combination of:

an elongated flexible tension member to support loads;

fluid motor means connected to said rotary means for actuation thereof;

fluid pump means to actuate the fluid motor means;

through a range of positions representing a range of speeds of the rotary member;

switch means mounted on the speed control member and movable independently thereof to a raise position, a lower position, and a stop position; and

said supply valve means and directional valve means responsive to said switch means.

Claims

1. In a hoist system for lifting and lowering loads from a hovering type aircraft, the combination of: an elongated flexible tension member to support loads; rotary means on the aircraft in engagement with the tension member for extension and retraction thereof; fluid motor means connected to said rotary means for actuation thereof; fluid pump means; means connecting the pump means to the motor means for flow of fluid thereto, said connecting means including reversible means operable in one respect for flow of fluid in one direction through the fluid motor means to cause the tension member to travel in one direction and operable in the opposite respect for flow of fluid in the opposite direction to cause the tension member to travel in the opposite direction; means for remote operation of said reversible means in its opposite respects selectively to control the direction of travel of the tension member; means to vary the displacement of one of said pump means and said fluid motor means to control the rate of travel of the flexible member; said motor means being constructed to act as temporary pump means on said fluid with the temporary pump means actuated by the weight of a descending load on the tension member; means to restrict the fluid discharge of the temporary pump means to retard the lowering of the load and said restricting means is normally ineffective; brake means to retard the lowering of the load; and means to make the restricting means effective in response to rise in temperature of the brake means.

2. In a hoist system for lifting and lowering loads from a hovering type aircraft, the combination of: an elongated flexible tension member to support loads; rotary means on the aircraft in engagement with the tension member for extension and retraction thereof; fluid motor means connected to said rotary means for actuation thereof; fluid pump means to actuate the fluid motor means; solenoid-actuated supply valve means between the pump means and the motor means operable to permit the pump means to actuate the motor means; solenoid actuated directional valve means between the pump means and the motor means to control the direction of rotation of the motor means; means to vary the displacement of one of said pump means and said motor means to vary the rate of operation of the motor means; a hoist controller; a manually operable speed control member movable independently of the controller through a range of positions representing a range of speeds of the rotary member; means to indicate to the hoist controller the position of said control member; a servo loop including means responsive to the hoist controller to regulate said displacEment means and including means to sense the speed of the rotary means to cause changes in speed of the rotary means to substantially follow changes in position of the speed control member; manually operable actuation control means having a ''''raise'''' position, a ''''lower'''' position and a ''''stop'''' position, said supply valve means and directional valve means being responsive to said manually operable control; and said actuation control being finger-actuated switch means mounted on said manually operable speed control member.

3. A hoist system for lifting and hovering a load from an aircraft, including: an elongated flexible tension member to support the load; rotary means on the aircraft engaging the tension member for extension and retraction thereof; at least one brake disk releasably engaging the rotary means; a pressure member engaging at least one of the brake disks on the side thereof remote from the rotary means; biasing means engaging the pressure member normally to maintain the disks in an engaging relationship with the rotary means so that the braking means normally inhibits the rotation of the rotary means; lever means engaging the pressure member and operative to move the pressure member outwardly to oppose the bias of said biasing means so that the brake disks engage the rotary member; operating rod means extending axially of said rotary means; a plurality of first levers pivotally mounted on the aircraft; a plurality of second levers linking the first levers with the pressure member; and the operating rod being movable in a first axial direction to engage the first levers whereby further movement of the operating rod in the first direction opposes the bias of the pressure member.

4. A hoist as in claim 3 wherein the braking means includes a supporting member having a substantially fixed relationship with the aircraft for supporting the rotary means; and a bath of oil confined by the supporting member to provide lubrication for the braking means.