Abstract: In a control (100) for a variable displacement hydraulic motor (12) having an electrically controlled hydraulic servo valve (14) for controlling the displacement of a hydraulic motor by varying position of a wobbler (28) in response to a servo valve control signal, a velocity transducer (72), coupled to a shaft (30) driven by the motor, for providing a velocity signal representative of the velocity of the shaft, and a wobbler position sensor (84), coupled to the wobbler, for producing a wobbler position signal indicative of the position of the wobbler, an improvement in accordance with the invention includes a controller (100) for producing the servo valve control signal as a function of a wobbler position command specifying a position of the wobbler wherein the wobbler position command is a function of at least one of the velocity signal representative of the velocity of the shaft and the wobbler position signal.

Abstract: A swashplate type hydraulic axial piston machine whose swashplate is arranged on a rocker mounted to pivot in a segmental rolling contact bearing has a tracking device for the cage of the pivot bearing which comprises a rod-like guide element which is connected to said rocker in a first bearing in the rocker so that it can pivot parallel to the pivot plane (SE), is connected to said cage in a second bearing so that it can pivot parallel to the pivot plane (SE) and so that it can be displaced longitudinally, and is mounted to pivot parallel to the pivot plane (SE) in a third bearing. To make tracking by the cage possible without mounting the guide element on the housing, a rocker adjustment member is provided mounted so that it can be displaced transverse to the middle axis of the axial piston machine, and the third bearing is arranged on a guide member movably connected to the adjustment member and the rocker.

Abstract: A control system (33, 41) is disclosed of the type used to control the displacement of a variable displacement pump (11) having stroking cylinders (25, 27). The control system includes a pair of ON-OFF electromagnetic valves (49, 51) and a proportional valve (85). When a first direction of operation is selected, a first direction command signal (43) is transmitted to the first ON-OFF valve (40) such that control pressure from the charge pump (17) flows through the valve (49), then through the proportional valve (85) and through the valve (51) to the reservoir (75) until the proportional valve (85), in response to an increasing displacement signal (47), moves from its minimum displacement position (FIG. 1) toward a position corresponding to the desired displacement of the pump.

Abstract: A swash plate type compressor having a pair of axially combined front and rear cylinder blocks forming therein a plurality of cylinder bores, a swash plate chamber, and an oil chamber in which a lubricating oil is stored to be stirred by a swash plate rotatably received in the swash plate chamber, a drive shaft centrally rotatably mounted in the combined cylinder blocks to cause a rotation of the swash plate, a plurality of reciprocatory double-headed pistons slidably fitted in the cylinder bores and operatively engaged with the swash plate via shoe members to be reciprocated by the rotation of the swash plate, a pair of thrust bearings axially supporting the swash plate, front and rear housings having suction chambers for the refrigerant gas before compression and discharge chambers for the refrigerant gas after compression, the front housing further having a shaft sealing chamber formed therein and separated from the suction chamber thereof to define an intermediate pressure chamber between the high pressur

Abstract: A swash-plate type compressor comprises a plurality of cylinder chambers parallel to each other, a shaft, a swash plate connected to the shaft for rotation therewith and for wobbling motion due to the rotation, and a plurality of pistons subject to wobbling motion of the swash plate for reciprocation within the respective cylinder chambers. The shaft and the swash plate are connected to each other through a slot formed in one of them and a pin provided on the other, so the swash plate can wobble. A position of a center of rotation of the swash plate is supported by a spool device movable in coaxial relation to the shaft. Displacement of the spool device causes the position of the center of rotation of the swash plate and an inclination thereof to be varied to vary a reciprocative stroke of each piston, thereby controlling discharge capacity of the compressor.

Abstract: A variable displacement piston pump includes a plurality of axially aligned pumping cylinders with a drive shaft extending therebetween having a pivotable swash plate disposed in a relatively dry cavity at one end of the drive shaft for operating the pumping cylinders, and a reaction thrust plate on the other end of the drive shaft for providing a reaction force on the drive shaft opposite that provided by the swash plate. An inlet shaft seal prevents fluid, which enters the pump at the inlet port, from filling the mounting housing and submerging the mount shaft portion of a rotating assembly supporting the swash plate. Two needle roller bearings support the swash plate and transmit torque from the drive coupling to the swash plate. A high pressure fluid restrictor meters hydraulic control fluid to the two needle bearings.

Abstract: A variable displacement hydrostatic axial piston machine has a cylinder barrel which is rotatable in a yoke and has a plurality of circumferentially spaced cylinder bores in which are mounted pistons which with the ends of their associated piston rods are journalled in a drive disk on a machine shaft rotatably mounted in the casing of the machine. The yoke is mounted in said casing pivotable about a transfer axis through the drive disk center by means of an adjustment device for varying the displacement and possibly also the mode of the operation of the machine, in the yoke and the machine casing furthermore being disposed a pair of hydraulic fluid connecting conduits.

Abstract: In a control cylinder device of a variable displacement compressor, an annular cylinder concentric with a driving rotary shaft is provided in a housing of a compressor body, and an annular control piston is slidably fitted in the cylinder to define a control pressure chamber within the cylinder. The annular control piston is connected to a sleeve, such that the sliding movement of the sleeve can be controlled by the operation of the control piston. Further, inner and outer seal rings are interposed in an axially misaligned relation to each other between inner and outer slide surfaces of the cylinder and control piston. This facilitates an accurate formation of the inner and outer surfaces of the cylinder in the cylinder device on which the control piston slides. Also, this easily insures sealing properties required between the slide surfaces of the cylinder and the piston. In addition, it is possible to effectively prevent the inclination of the control piston within the cylinder.

Abstract: A speed control system for a working vehicle comprises a hydrostatic transmission for propelling the vehicle, a hydraulic cylinder and a control valve. The hydraulic cylinder includes a cylinder case operatively connected to a control shaft for varying a swash plate angle of the hydrostatic transmission, and a piston rod fixed to a case containing the hydrostatic transmission. The control valve is fixed to the cylinder case and includes a spool extending parallel to the hydraulic cylinder and operatively connected to a foot pedal for manually controlling the hydrostatic transmission. The cylinder case is shiftable following a shift of the valve spool.

Abstract: A variable displacement type compressor includes a casing having a working chamber and cylinder bores provided therein and opened to face to the working chamber. The cylinder bores are disposed around a driving shaft rotatably carried in the casing. A working piston is slidably received in each of the cylinder bores. A sleeve is axially slidably fitted over the driving shaft within the working chamber and carries a holder mounted for swinging movement about an axis perpendicular to an axis of the driving shaft and connected to the driving shaft. A swingable swash plate is carried on the holder and connected by rods to the working pistons. A control piston is connected to the sleeve and slidably received in the casing to vary the angle of inclination of the holder and the swingable swash plate and vary the stroke of the working pistons.

Abstract: An energy conserving highly efficient hydraulically energized cooling tower fan system is provided having a rotary fan and hydraulic motor for operation thereof located at elevation within the upper portion of a cooling tower. An axial piston, variable displacement, pressure compensation hydraulic pump and its electric motor, together with a hydraulic fluid reservoir, hydraulic fluid filters and coolers arranged in closed loop assembly are located remotely from the hydraulic motor and fan assembly such as at ground level, to facilitate ease of maintenance and to minimized fire hazard and electrical hazard within the cooling tower itself. The rotational speed of the cooling tower fan is within a predetermined infinitely variable range and is controlled responsive to the temperature sensed in the cool water basin of the cooling tower by a temperature sensor and controller which controls the velocity of fluid output from the hydraulic pump.

Abstract: A variable displacement hydraulic motor is easily mounted on a power shovel without interfering with a truck frame of the power shovel and without projecting outward therefrom. The hydraulic motor is easily assembled and machined in its manufacturing. In the hydraulic motor (M'), there is provided an end cover (57) in which is slidably mounted a piston lever (69) which is oppositely disposed from a drive shaft (44) of the hydraulic motor (M') to extend in a direction perpendicular to an axis of the drive shaft (44). Since the hydraulic motor (M') is provided with a valve plate swinging unit having a pin (71) through which the piston lever is connected with a valve plate (59) fixedly mounted on a cylinder block (60), it is possible to directly mount the end cover (57) on a main casing (50) of the hydraulic motor (M') so as to be perpendicular to the axis of the drive shaft (44).

Abstract: In an axial piston pump of fixed or adjustable displacement having a two-part housing, namely a housing part accommodating the pistons and a connecting part through which the pressure passage and the suction passage extend, the suction passage having a suction opening with a larger cross-section than that of the pressure passage, the connecting part can be mounted to the housing part as desired in two positions turned substantially through 180.degree. about the center axis of the axial piston engine. This construction enables the pump to be adapted to operate with either direction of displacement with little trouble and expense.

Abstract: An electrohydraulic system for control of a variable output pump includes a microprocessor-based controller receiving inputs from condition sensors coupled to the pump and command inputs from a remote master controller. The controller supplies outputs to an electrohydraulic valve for metering hydraulic fluid to a pump control port and thereby controlling pump operation in any one of a number of preselected and prestored pump control modes. A hydromechanical valve is connected in parallel with the electrohydraulic valve for controlling pump operation in the event of electrical malfunction or failure. Circuitry connected between the pump condition sensors and the control computer prevents aliasing errors due to mismatch between the computer sampling frequency and pump speed.

Abstract: A variable displacement swash-plate type compressor has a swash plate rockably carried by a shaft, and a spool for changing the angle of tilt of the swash plate and also the position of the center of the swash plate, thereby to vary the displacement of the compressor. The compressor has a control valve which determines a control pressure to be supplied to a control pressure chamber behind the spool, between the level of a low-pressure introduced from a low-pressure side of the compressor and a high-pressure introduced from a high-pressure side of the compressor.

Abstract: The invention involves improvements to an axial piston fluid device of the type having a housing with a central cavity and a valve plate end, a shaft journaled adjacent its inner end in a bushing mounted in a bore in the valve plate end, and a cylinder barrel surrounding the shaft and rotatable therewith in the cavity and against the valve plate end. The invention utilizes a bushing which has a slot intermediate its ends and the valve plate bore has axial extending recesses leading to and away from the bushing slot. The cylinder barrel and valve end have a series of fluid passageways leading from the cavity to the bore and from the recesses to the space between the cylinder barrel and shaft and then back to the cavity.

Abstract: A hydraulically operated continuously variable transmission for an automobile includes a hydraulic pump coupled to an input shaft and having an outlet port, a hydraulic motor coupled to an output shaft, at least one of the hydraulic pump and the hydraulic motor being of the variable-displacement type, a closed hydraulic circuit interconnecting the hydraulic pump and the hydraulic motor, and a device for selectively making and breaking the hydraulic circuit respectively by opening and closing the outlet port. The device comprises a valve body for closing the outlet port, a valve holder for driving the valve body to selectively open and close the outlet port, and a spring for normally urging the valve body in a direction to close the outlet port, the valve body and the valve holder being held in engagement with each other for relative displacement in directions to open and close the outlet port.

Abstract: A swashplate type variable displacement hydraulic device is so constructed that a plurality of plungers are slidably received in a plurality of cylinder bores arranged annularly around an axis of rotation, a back surface of a swashplate of which a fore surface is engaged by outer ends of the plungers is supported by a swashplate holder via bearing means, and a stationary swashplate anchor supports the swashplate holder to turn about a trunnion axis which intersects the axis of rotation at right angles. Opposing surfaces of the swashplate holder and swashplate anchor are formed as spherical surfaces of which a center is located at a position where the axis of rotation intersects the trunnion axis, the swashplate holder has a pair of trunnion shafts projected from opposite ends of the swashplate holder while extending along the trunnion axis, and the trunnion anchor is formed at opposite ends thereof with recesses with which the trunnion shafts are rotatably engaged.

Abstract: A hydraulically operated swash-plate apparatus includes a cylinder block rotatably supported in a case and having a plurality of axial cylinders arranged in an annular pattern, the case having an end plate for bearing a thrust load from the cylinder block, a plurality of plungers received respectively in the cylinders, a swash plate supported in the case by trunnions and slidably held against the free ends of the plungers, an actuator for tilting the swash plate, the plungers being movable into and out of the respective cylinders by a stroke which is variable according to the angle of inclination of the swash plate, a support member by which the trunnions are rotatably supported, and a tension member coupling the end plate and the support member to each other. The apparatus also includes a stopper mounted in the case for engaging a back of the swash plate to limit the maximum angle of inclination of the swash plate.

Abstract: A system for hydrostatic pressure release of the rocker in the bearing box in an axial piston machine. The pressure-relief system includes slots in the rocker bearing box connected with axial passages through the pistons, pressure pockets in the guide shoes and passageways through the rocker. In order to render the forces in the pressure-relief system essentially constant and speed-independent, the pressure-relief devices of the rocker bearing and four individual slots, two of which are parallel to each other in the region of each of the two bearing surfaces on the rocker and which are connected to the pressure pockets in the guide shoes by the passageways through the rocker.

Abstract: A vehicle includes at least a pair of drive wheels, each wheel being independently controlled by an integrated transmission, each transmission being powered by an input shaft operably driven by a common engine. Each transmission is of a type wherein a pump head with pistons is driven by the input shaft and conveys output fluid to a motor head which is driven thereby and rotates an output shaft. Pump head output is controlled by an operator variable swash plate. The transmission integrally includes a dampening mechanism for the swash plate, a positive neutral structure for the swash plate, an automatic parking brake with override mechanism to allow setting of the brake or release of the brake by the operator, a porting block communicating fluid flow between the pump heads and providing for overpressure relief, and a charge pump for communicating makeup fluid to the pump head and to circulate the fluid so as to cool same.

Abstract: An adjustable axial piston machine is disclosed which has a housing, a cylinder drum and an operating cylinder-servo piston unit capable of being acted upon by control pressure. The cylinder-servo piston unit has a movable part which is being connected with a control of the axial piston machine. The operating cylinder-servo piston unit has an annular configuration and is located around the cylindrical drum.

Abstract: An adjustable axial piston machine having a bent axis design having a cylindrical drum rotatably supported on a swivel carriage which has a pair of channels formed therein. One channel is connected with a fluid feed channel and the other channel is connected with a fluid discharge channel. The cylindrical drum is connected to a rotatable shaft and has a plurality of pistons located in cylinders formed in it. A housing for the swivel carriage has a concave guide surface for the face of the swivel carriage facing the guide surface. Support pistons are pivotably connected at one end to the machine housing and supported on the swivel carriage. A plurality of pairs of counteracting servo pistons adjust the position of the support pistons and the cylindrical drum to modify the length of the stroke of the pistons located within the drum.

Abstract: A variable displacement swash-plate type compressor suitable for use as a refrigerant compressor of an automotive air conditioner has a cylinder block having a plurality of cylinder bores each slidably receiving a double-headed piston, a shaft driven by an automotive engine, a swash plate tiltably mounted on the shaft for rotation therewith to reciprocatorily move the pistons, and a spool for moving the swash plate axially of the shaft and changing the angle of tilt of the swash plate. The swash plate and the shaft are connected in such a manner that, when the swash plate is axially moved while changing its tilting angle, the position of stroke end of each piston is changed only in a working chamber on one end of the piston, whereas no change in the position of the stroke end occurs in the other working chamber on the other end of the piston.

Abstract: A bent axis type axial piston pump or motor wherein the cylinder block is rotatable in synchronizm with the torque plate about an axis inclined relative to the axis of rotation of the torque plate. The shaft of the torque plate passes through the inclined cylinder block without mutual mechanical interference and is supported by bearings at the opposite sides of the casing. The torque plate and the cylinder block are connected by a mechanism which ensures exact synchronization of rotation of the two members. A static pressure balance is established between the working fluid acting on the opposite sides of the torque plate, the cylinder block and the pistons, respectively. The angle of inclination of the cylinder block with respect to the shaft can be changed thereby to change the capacity of the pump or motor. The pump or motor of this invention may be provided in a tandem type.

Abstract: A static hydraulic pressure type continuously variable transmission formed with a hydraulic closed circuit between a swashplate type hydraulic pump and a swashplate type hydraulic motor, the hydraulic motor being constructed such that its motor cylinder is integrally connected to an output shaft which extends through a motor swashplate and a swashplate holder for supporting the back surface of the motor swashplate, a swashplate anchor for supporting the back surface of the swashplate holder being axially immovably connected to the output shaft through a thrust bearing, and that the swashplate anchor is unrotatably connected to a casing which rotatably supports the output shaft. The motor cylinder and a pump cylinder of the hydraulic pump are provided coaxially with the hydraulic closed circuit interposed therebetween.

Abstract: A hydraulic drive circuit system is equipped with an accelerator pedal and an accelerator lever for respectively instructing target revolution numbers for an engine, a link plate for selecting greater one of the instruction values, and a linkage and a switch for controlling valves respectively so as to close the flow passage of a line interposed between a charge pump and a low pressure line irrespective of the instruction value of the accelerator pedal when the accelerator lever has not been controlled but for controlling the valves so as to restrict the flow passage of the line in accordance with the instruction value of the accelerator pedal when the accelerator lever has been controlled.

Abstract: A static hydraulic continuously variable transmission includes a cylinder block which is secured to an output shaft and comprises a pump cylinder of a hydraulic pump and a motor cylinder of a hydraulic motor, these cylinders being connected to each other, wherein, a number of pump cylinder bores and a number of motor cylinder bores are annularly arranged respectively in the pump cylinder and the motor cylinder and the transferring of a working oil between the group of the pump cylinder bores and the group of the motor cylinder bores is conducted through the medium of a pair of oil chambers which are concentrically provided around the output shaft communincation between these cylinder bores is controlled by a number of first and second dispensing valves extending between both the oil chambers and adapted to be reciprocally radially moved.

Abstract: An adjustable axial piston machine of swash plate construction is provided in which the working pistons are supported against a swash plate that is formed on a rocker body 6, which in turn is supported with a semi-cylindrical support surface against a hollow-cylindrical bearing surface 4, in which case at least one pressure pocket recess 7, 57 is provided for generating a pressure cushion counteracting the bearing loads and it is connected with the high pressure line through channels in the servo piston that is capable of sliding in the operating cylinder loaded with high pressure.

Abstract: A servo system having a circuit for developing an error signal representing the deviation of a load condition from a desired condition represented by a command signal and forward and feedback paths at least one of which includes an impedance therein represented by a transfer function comprises a limiter receiving the command signal and connected to the error signal developing circuit for controllably limiting the command signal wherein the limiter has a variable saturation point and a circuit coupled to the limiter and to the impedance for controlling the saturation point of the limiter in accordance with the transfer function of the impedance to enable fast response without damage to an output device controlled by the servo system.

Abstract: The heretofore known adjusting device for an axial piston pump/motor of a tilting axis type in which a tilt angle of a valve plate is varied by rocking the valve plate along arcuate guide grooves formed in an end cover of the axial piston pump/motor is improved so as to reduce the size of the adjusting device in the direction of its stroke by assembling a sleeve or sleeves and a piston fitting in the sleeve or sleeves in a telescopic structure within a cylinder formed in the end cover along a rocking direction of the valve plate, and by providing a trunnion pin engaged with the valve plate in the piston.

Abstract: A rotary hydraulic machine which includes a housing having a shaft mounted for rotation within the housing about a shaft axis. A cylinder block is coupled to the shaft for corotation with the shaft within the housing and includes a plurality of cylinders disposed in a circumferential array parallel to and surrounding the shaft axis. A piston is disposed to reciprocate within each of the cylinders and is coupled to a yoke for determining displacement of the pistons within the cylinders. A valve plate is affixed within the housing and includes arcuate slots at a radius from the axis of rotation corresponding to that of the cylinders. The slots respectively connect cylinders to the machine inlet and outlet ports as the cylinders register with the slots.

Abstract: A gas compressor has a cup-like casing. A driving shaft is rotatably carried by a bottom of the casing and has a rotary plate secured thereto. A driven shaft is disposed in the casing at an inclination angle of 20.degree. against the driving shaft, supported by a bearing provided on an end of the driving shaft, and driven by the driving shaft. A cylinder block is fixed to the driven shaft and has a cylinder bores receiving pistons coupled with the rotary plate so that the pistons reciprocate in the cylinder bores upon rotation of the driving shaft. A side plate is secured to an open end of said casing and has a bore receiving a bearing for supporting one end of the driven shaft. The bore is formed in the inside the side plate which projects outside, so that a distance between the bearing of the driving shaft and the bearing in the bore is extended and stable.

Abstract: A clutch valve system for use in a static hydraulic continuously variable transmission in which a hydraulic closed circuit is formed between a swashplate type hydraulic pump and a swashplate type hydraulic motor, wherein a first annular oil chamber and a second annular oil chamber are concentrically defined in the pump cylinder adjacent to annularly arranged cylinder bores of a pump cylinder in the hydraulic pump, the first oil chamber being adapted to be connected to the cylinder bores which are in a discharge stroke and the second oil chamber being adapted to be connected to the cylinder bores which are in a suction stroke; a plurality of clutch valves are radially arranged in the pump cylinder for providing the communication or discommunication between both the oil chambers by the radial movement thereof; and a clutch control ring engaged with the clutch valves for relative rotation therebetween so as to surround these clutch valves is pivoted on a fixing structure for pivotal movement between a clutch ON

Abstract: A swashplate type hydraulic pressure device comprising a cylinder and a swashplate which is rotatable relative to the cylinder and rotatably supported on a holder, the cylinder having a number of plungers disposed thereon axially slidably in an annular arrangement, in which a spherical end is formed at that extreme end of each plunger which is in abutment with the swashplate, and the swashplate is provided with a spherical concave portion for engagement with the spherical end. By cooperation between the spherical concave portions and the ends, the cylinder rotates synchronously with the swashplate and an aligning action is imparted to the swashplate from the group of plungers of the cylinder.

Abstract: A static hydraulic pressure type continuously variable transmission having a hydraulic closed circuit formed between a swashplate type hydraulic pump and a swashplate type hydraulic motor, in which a high pressure oil passage is communicated through exhaust valves with a number of cylinder bores annularly disposed in a pump cylinder of the hydraulic pump, a low pressure oil passage is communicated through intake valves with the cylinder bores, and a number of distribution valves capable of being reciprocated are radially disposed so as to provide an alternate communication between a number of cylinder bores annularly disposed in a motor cylinder of the hydraulic motor and the high and low pressure oil passages. An eccentric ring for imparting reciprocation to each distribution valve is provided and a discharge side of a replenishing pump is communicated with an inner end surface of each distribution valve to hydraulically urge the distribution valve in a direction of engagement with the eccentric ring.

Abstract: A variable displacement axial piston device has a movable swashblock, the front face of which is engaged by shoes pivotally mounted on the end of pistons operating in a plurality of cylinders formed in a cylinder barrel. The rear of the swashblock has a pair of arcuate bearing surfaces and a support is provided in the device for such bearing surfaces. A pair of arcuate bearings are disposed between the support and the swashblock bearing surfaces. At least the one swashblock bearing surface that is opposite the high pressure port of the device has a continuous groove that faces the respective bearing. A passageway is formed internal of the swashblock and terminates in the groove. An opening with an orifice is provided in the front face of the swashblock leading to the passageway from a position that is axially aligned with the one bearing surface and in the path of the shoes as they pass over the front face of the swashblock.

Abstract: The invention relates to an adjustable axial piston engine having spaced apart end walls with a shaft extending between the end walls. A rotary carrier is attached to the shaft adjacent one of the end walls and an oblique adjusting plate is mounted adjacent the other end wall. A piston-cylinder unit extends between the carrier and the oblique plate. A pivot axis for the oblique plate includes a bearing arrangement between the plate and the adjacent end wall. A servo unit for adjustably rotating the plate about the pivot axis is provided between the plate and the adjacent end wall.

Abstract: This invention relates to an axial piston system hydraulic pump or motor capable of being changed over by two stages and particularly preferably used as the hydraulic motor for driving vehicles such as bulldozer, shoveldozer, etc. Thus, to provide as compact as possible two step changing-over mechanism and a well-balanced operation with a relative small force, a smooth plane against which the shoe at the plunger side opposed to a swash plate abuts and a first and second abutting portions located at the opposite plane to the smooth plane to abut against a fixed portion, when the swash plate pivots about the center of pivotal movement, to regulate the angle of said smooth plane of the swash plate to two positions are formed while a drive member is disposed which pivots said swash plate about the center of the pivotal movement to displace the angle of the smooth plane to two positions.

Abstract: In a positive displacement variable stroke motor, a constant speed variable power drive governor is disclosed which varies stroke instead of driving pressure and hence conserves power through reducing throttling losses. Typically, the control is used on at least one of a plurality of motors all driven from the high pressure manifold of a pressure compensated controlled pump driven by a prime mover. The particular controlled positive displacement variable stroke motor is connected at fluid intake to the high pressure manifold on the high pressure fluid side and discharges to a reservoir on the low pressure fluid side. The controlled motor also drives a small positive displacement pump--typically an in situ charge pump--and produces a discharge through a square edge orifice in an insolated hydraulic control circuit. In response to load changes, a hydraulic amplifier monitors the pressure in the hydraulic control circuit and changes the motor stroke, typically by changing tilt box angle.

Abstract: A power drive unit and control system therefor avoiding performance degradation which can occur in control of the variable displacement hydraulic motor of the power drive unit by measurement of the angle of a displacement-setting wobbler of the motor and the speed of the motor. This is avoided by sensing flow through the motor which provides an indirect measure of wobbler position and speed of motor operation. The power drive unit and control system therefor has a variable displacement hydraulic motor with a displacement-setting wobbler positioned by pressure applied to a servo piston by an electro-hydraulic servo valve. The control system responds to a speed command having a value dependent upon a position loop which determines the relation between the actual position of a load and a commanded position, with the control providing for a maximum possible speed of motor operation under a particular load condition with a substantially constant rate of fluid flow through the motor.

Abstract: This invention relates to an energy efficient variable displacement motor-driven power drive unit using a multi-variable feedback control system to control system output position and speed. More particularly, a variable displacement hydraulic motor connected to drive a load has a variable-position wobbler, with the position controlled by electro-hydraulic servo means including an electrically-operable servo valve which receives a control signal from signal summing means which has summed feedback signals representing speed and position of a load with a torque signal representative of wobbler position. The latter signal is mechanically inputted to the servo valve by means of a mechanical connection including a link connected to the wobbler and a spring interconnecting the link to the servo valve and with the link carrying a servo piston movable in a servo cylinder associated with the servo valve.

Abstract: The invention is concerned with an axial piston machine, preferably an axial piston pump of the inclined disc or skew axis type, with a cylinder (9) which rotates about an axis of rotation and in which, on a pitch circle, several pistons (8) are movably guided in piston bores (11) extending substantially along the axis of rotation (3), by means of an inclined or driving disc, or the like, the piston bores (11) opening at the face of the cylinder (9) which is remote from the inclined or driving disc (5), the face resting against a control surface (13) in which there are arranged control openings (14), positioned on the pitch circle of the pistons (8) which, in set positions of rotation of the cylinder (9) are covered by the openings of the piston bores (11), loading cylinders (24) being distributed over the circumference and acting upon the cylinder (9) against the control surface (13), and of which loading cylinders the working spaces are connected, by means of connecting channels (27), each with a respective

Abstract: The invention relates to a swashplate leveling and holddown mechanism wherein an axially sliding leveling mechanism is biased into engagement with a swashplate of an axial piston variable displacement hydraulic unit to position the swashplate in a zero displacement position when there is no control input to the hydraulic unit. The leveling mechanism has a pair of contact points, one positioned on each side of the swashplate tilt axis in a manner that both contact points positively engage the swashplate when it is centered to its zero displacement position. Such mechanism requires no spring adjustment and has no backlash. Furthermore, the axial bias on the leveling mechanism helps seat the swashplate in its support bearings. Utilized in conjunction with the leveling mechanism is an axially biased control input which operates on the opposite side of the swashplate to further hold the swashplate in its support bearings.

Abstract: The invention relates to a hydrostatic axial piston machine (1) having a cylinder drum (9), rotating in a housing, which cylinder drum receives pistons (12) arranged on a pitch circle, and having an inclined disc (16) which pivots, in a pivot, about a swivelling axis (21) which extends eccentrically to the pitch circle, which pivot is formed by at least one bearing (23) having a bearing surface (26) which is free in the direction of the pistons (12), the inclined disc (16) being arranged loosely between the bearing (23) and the pistons (12) and being pivotable by means of an adjusting member (28). The aim of the invention is to develop the axial piston machine so that, while ensuring a simple structural design sign and simple assembly and dismantling of the inclined disc (16) and of the adjusting member (28), defined limitation of the adjusting movement of the inclined disc (16) in the direction of zero position or minimum delivery is possible.

Abstract: A power drive unit for thrust reverser structure includes a reversible motor in a hydraulic circuit and has normal stow and deploy cycles of operation. In a deploy cycle, the load on the motor is aiding and, in the event the deploy cycle is inadvertent, the load on the motor can be substantially higher. In order to avoid this increased loading on the motor in an inadvertent deploy cycle, the hydraulic circuit has an auto-restow valve which senses the high aiding load in the event of an inadvertent deploy operation and changes the operation of the power drive unit to operate the motor in a stow cycle to prevent continued high loading on the motor and thrust reverser structure.

Abstract: A multiple displacement motor driven power drive unit having two separate hydraulic systems each with a variable displacement hydraulic motor having its output connected to a torque summing gear train. A control provides for operation of one or the other of the motors at full displacement while the other motor is at zero displacement and free-wheels. There is a manual mechanical control operation with both motors simultaneously set at one-half of full displacement and driving the torque summing gear train. The change in motor displacements to one-half full displacement accomplishes velocity summing within the hydraulics. The multiple displacement motor driven power drive unit accomplishes the power efficiency of a multiple motor driven power drive unit utilizing a speed summing gear train with fixed displacement motors, but without the complexities associated with the use of a speed summing gear train and brakes.

Abstract: A fluid device of the axial piston type having high and low pressure operating passages, one of which may be an inlet and the other an outlet depending upon the pumping or motoring function of the device. The fluid device which may be of the fixed or variable displacement type has a rotatable cylinder barrel with each end of a plurality of pistons disposed for reciprocation within cylinder bores in the cylinder barrel, and cylinder ports successively communicating each of the cylinder bores with arcuate inlet and outlet passages formed in a valving face disposed at one end of the cylinder barrel. The other ends of the pistons are drivingly engaged by an inclined thrust plate assembly disposed to impart a reciprocal stroking movement to the pistons within the cylinder bores as the cylinder barrel is rotated.

Abstract: A fluid device of the axial piston type having high and low pressure operating passages, one of which may be an inlet and the other an outlet depending upon the pumping or motoring function of the device and the direction of rotation. The fluid device, which is of the variable displacement type, has a rotatable cylinder barrel with one end of each of a plurality of pistons disposed for reciprocation within cylinder bores at one end of the cylinder barrel, and cylinder ports successively communicating each of the cylinder bores with arcuate inlet and outlet passages formed in a valving face disposed at the opposite end of the cylinder barrel. The other ends of the pistons engage a pivotably mounted thrust plate adapted to impart a reciprocal movement to the pistons within the cylinder bores as the cylinder barrel is rotated.

Abstract: A swashplate type hydraulic pressure device comprising a cylinder and a swashplate which is rotatable relative to the cylinder and rotatably supported on a holder, the cylinder having a number of plungers disposed thereon axially slidably in an annular arrangement, in which a spherical end is formed at that extreme end of each plunger which is in abutment with the swashplate, and the swashplate is provided with a spherical concave portion for engagement with the spherical end. By cooperation between the spherical concave portions and the ends, the cylinder rotates synchronously with the swashplate and an aligning action is imparted to the swashplate from the group of plungers of the cylinder.