Abstract: A continuously variable transmission employing a hydraulic motor and a hydraulic pump that are interconnected by a closed hydraulic circuit. An oil chamber is defined between the pump cylinder of the hydraulic pump and the motor cylinder of the hydraulic motor. A common oil cooling unit is connected through oil passages to the closed hydraulic circuit and the oil chamber for cooling heated oil supplied therefrom. The common oil cooling unit effectively cools the oil from the two sources since the heat developed in the oil from the two sources generally varies inversely during different modes of operation.

Abstract: A hydraulically operated continuously variable transmission includes a hydraulic pump coupled to an input shaft, a hydraulic motor coupled to an output shaft, a closed hydraulic circuit interconnecting the hydraulic pump and the hydraulic motor, and a control valve coupled to an inlet of the hydraulic pump and openable for discharging working oil from the hydraulic pump when the pressure of oil in the inlet of the hydraulic pump is below a prescribed pressure level. The transmission also includes a hydraulically hermetic chamber defined between the pump and motor cylinders and accommodating therein the pump swash plate and the pump plungers, and oil discharge means disposed in the motor cylinder for discharging oil from the hydraulically hermetic chamber when the pressure of oil in the hydraulically hermetic chamber is below a prescribed pressure level.

Abstract: An integrated hydrostatic transaxle having a common housing for a hydrostatic transmission and a pair of oppositely-extending differentially-connected axles to have the common housing provide a common sump therefor and with a specifically-shaped center section interconnecting the pair of hydraulic displacement units constituting the hydrostatic transmission. The center section is a unitary member separate from the common housing, with the exterior thereof exposed to the common sump. The center section has passages and arcuate ports which are interconnected by certain of said passages and which are located whereby the center section may be cast to minimize any machining required to finish the center section. Such casting can result in a porous center section with possible leakage from a passage having high pressure fluid.

Abstract: A hydraulically operated continuously variable transmission comprises a hydraulic motor coupled to an output shaft, a hydraulic pump coupled an input shaft, and a closed hydraulic circuit interconnecting the hydraulic motor and the hydraulic pump. The hydraulic motor has an annular array of slidable motor plungers disposed around an axis of rotation thereof and slidably disposed in respective cylinder holes defined in the motor cylinder. The hydraulic motor also has a distribution ring supported on the fixed shaft and rotatable relatively to and slidable against an end face of the motor cylinder for introducing high-pressure oil successively into the cylinder holes and discharging oil successively from the cylinder holes in response to rotation of the motor cylinder.

Abstract: A hydraulically operated continuously variable transmission includes a hydraulic pump coupled to an input shaft, a hydraulic motor coupled to an output shaft, a closed hydraulic circuit interconnecting the hydraulic pump and the hydraulic motor, a hydraulic actuator for actuating a controlled member in the closed hydraulic circuit, an auxiliary pump connectable to the closed hydraulic circuit and the hydraulic actuator, a supply oil passage for supplying oil discharged from the auxiliary pump to the hydraulic actuator, and a control valve coupled between the supply oil passage, the closed hydraulic circuit, and an oil tank. The control valve comprises a hydraulic chamber communicating with the supply oil passage, a spring, and a spool disposed between the hydraulic chamber and the spring.

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: A hydrostatic machine including a casing 1 containing a rotary member 12 having radial cylinders 20 each with a piston 21 engaging a track ring 23. Both input 6 and output shafts 7 are connected either hydraulically through the transmission rotary members 12 or mechanically through a bypass shaft 10 and clutch 50 for reducing machine heat losses. Hydraulic ram 106,110 assistance for cushioning out pressure transients when transmission power returns from mechanical to hydraulic. Internal oil ducts 72,80.90 included for providing further temperature control for the main internal transmission component parts 14.24 said ducts 72,80,90 feed from a auxiliary fluid pump 8,9.

Abstract: A hydraulic motor and a hydraulic pump are interconnected by a closed hydraulic circuit. A lubricating chamber is defined around the sliding surfaces of the swash plate and the plungers of at least one of the hydraulic pump and the hydraulic motor. A hydraulically hermetic chamber is defined in surrounding relations to at least one of the hydraulic pump and the hydraulic motor. The hydraulically hermetic chamber is connected to a replenshing pump by a relief valve which is openable at a pressure level. A pressure control valve is disposed in a discharge passageway of the hydraulically hermetic chamber and openable at a first pressure level lower than the pressure level for the relief valve. In another embodiment, a second pressure control valve is connected to a junction between the first pressure control valve and the lubricating chamber and openable at a second pressure level lower than the second pressure level.

Abstract: A hydraulic pressure system comprising a hydraulic pump, a hydraulic motor, a pair of main hydraulic pressure lines connecting the pump and the motor so as to form a closed loop or circuit, a booster line for supplying a hydraulic pressure from a booster pump to the low pressure side of the closed circuit, a pilot line for taking out a pilot pressure from the high pressure side of the circuit to operate an actuator for controlling the hydraulic pump and the hydraulic motor, and a boost pressure regulator for causing the pressure in the booster line to rise only when the differential pressure between the two main hydraulic pressure lines of the closed circuit becomes lower than a predetermined level.

Abstract: An earthmoving machine comprises a first system for moving the machine, a second system for moving a mobile part of the machine, and an actuator device for the first or second system. The actuator device comprises a variable flowrate pump and a mechanism for adjusting the flowrate of the pump. A ram is mechanically coupled to this mechanism, and a hydraulic control circuit controlling the pump comprises a control pressure generator, an actuator member coupled to the generator and a variable ratio pressure divider connected between the generator and the actuator member. The first or second system comprises at least one control member adapted to be actuated by the actuator member when the actuator member has moved a predetermined distance beyond a neutral point.

Abstract: The present invention is a hydraulic transmission comprising a power input shaft, a variable displacement pump connected to and driven by the input shaft, a fixed displacement motor having a motor output shaft, a power take-off shaft, and an intermediate shaft. The intermediate shaft is connected between the power input shaft and the power take-off shaft for transmitting rotational movement directly therebetween. The intermediate shaft also includes first and second bores extending longitudinally therethrough and providing hydraulic connections from the variable displacement pump to the fixed displacement motor so as to permit the pump to drive the motor. Thus, the power input shaft drives the power take-off shaft directly and drives the motor output shaft by virtue of the hydraulic connection between the pump and the motor.

Abstract: A control circuit for a reversible hydrostatic transmission including a reversible pump having first and second working lines, and a control member having forward and reverse positions to normally direct a working fluid through the first and second working lines respectively. A servo-motor has forward and reverse positions to hold the pump control member in either its forward or reverse positions, and a first subcircuit is provided to conduct a control fluid to the servo motor to hold that motor in either its first or second positions. This first subcircuit includes a pair of piston and cylinder units, with each of these units having a control pressure chamber and a working pressure chamber.

Abstract: A prime-mover driven variable-rate pump of relatively great flow capacity is in delivery and return-circuit connection to an intermittently loaded hydraulic motor. A fixed-rate pump of substantially less capacity is continuously driven by the prime-mover, to charge a hydraulic accumulator, there being a safety relief to sump when a predetermined high-pressure threshold is reached. The accumulator is exclusively connected to the inlet of the variable-rate pump, being isolated by check valves from delivering any reverse flow to the fixed-rate pump and from delivering any reverse flow to the return portion of the motor-driving circuit. In said return portion, and between its check valve and the motor, a "dump" valve is operable for transient diversion of return flow to sump, thereby transiently enabling enhanced load-accelerating torque from the motor; this valve is preferably pressure-operated to "dump" position upon a load-reflecting pressure rise in the supply line from the variable-rate pump to the motor.

Abstract: A hydraulic drive system for driving a platen in forward and return reciprocatory strokes includes a hydraulically driven reciprocable piston and a reversible rotary hydraulic motor having a crank coupled to the platen by a link. A hydraulic circuit employs a variable output pump connected via a reversible direction control valve to drive the piston and crank in unison to cooperatively drive the platen. The piston and crank motor are connected in parallel to the pump and the pump output is advantageously distributed variably between the piston and motor during the stroke cycle. Where the stroke of the platen is vertical, the system may include a hydraulic counterbalance circuit to counterbalance the weight of the platen. The pump output may be varied to control the velocity of the platen at selected points in its stroke.

Abstract: A hydromechanical torque transmission device comprises three coaxial rotatable bodies. These are a driving body, an intermediary body and a driven body. The driving and driven bodies are adapted to be coupled to respective coaxial shafts that are to be coupled together in rotation. A speed correlator system is adapted to maintain the speeds of the driving and driven bodies relative to the intermediary body in a predetermined ratio. The intermediary body comprises a hydraulic circuit. The driving and intermediary bodies define a first pump adapted to cause a flow of fluid in this hydraulic circuit. The intermediary and driven bodies define a second pump also adapted to cause a flow of fluid in the hydraulic circuit. One at least of the first and second pumps has a variable volumetric capacity. The device also comprises means for controlling variations in this variable volumetric capacity.

Abstract: A control apparatus for a hydraulic motor for use in a construction vehicle driven by hydraulic power has a hydraulic motor, a hydraulic pump serving as a pressurized fluid supply source, a manually operable directional control valve connected across supply and discharge conduits for the hydraulic motor, a brake valve section including a counterbalancing valve and a pair of relief valves all of which are connected across the conduits extending between the directional control valve and the hydraulic motor, and a selector valve for controlling the supply of control pressurized fluid introduced through a shuttle valve connected across the conduits into a displacement control cylinder contained in the hydraulic motor. The selector valve is of a pilot operated type remotely controlled by pilot pressurized fluid supplied from an external pressurized fluid supply source.

Abstract: A vibration roller comprises a power limiting device (20) engaging the travelling lever (3), the vibration roller having a prime mover (1), a hydrostatic pump for the travelling drive, which hydrostatic pump is driven by the prime mover and arranged to be controlled by a travelling lever (3), and a vibration drive driven by the prime mover. The power limiting device comprises a stepped piston (27) slidingly movable in a stepped bore (24). The fluid pressure in the travelling drive and in the vibration drive engage the steps thereof. The stepped piston (27) is movable into the setting range of the travelling lever (3), by the sum of the fluid pressures, such that the maximum deflection of the travelling lever is limited to values, at which the total power consumption of the vibration roller does not exceed the limiting power of the prime mover.

Abstract: In a hydrostatic transmission of the type in which a motor and a variable displacement pump are coupled within a casing, both the motor and the pump are of the radial displacement type and each includes two oppositely phased reaction surfaces, so as to enable improved dynamic balance and a simpler and more robust construction. An engine starting function may also be provided.

Abstract: A hydraulic driving system for vehicles having separate drives for each wheel. The system includes a plurality of hydraulic motors connected in parallel to high-pressure and suction ports of a pump. At least one restrictor having a non-linear response is connected in the parallel supply conduits branching to respective hydraulic motors, to limit the flow rate when a motor operates under unloaded conditions.

Abstract: A control system for a hydraulically driven vehicle having a pair of closed loop each including a variable displacement hydraulic pump driven by an engine and a variable displacement hydraulic motor, the control system comprising a charge pump driven by the engine, a directional control valve for speed control and forward and reverse change-over of the vehicle connected with the charge pump, a pair of steering valves connected with the directional control valve, a pair of servo controls each operatively connected with the respective variable displacement hydraulic pumps for controlling the displacement volume thereof, another charge pump driven by the engine, and a manually operated selector valve connected with the another charge pump and the servo controls, the selector valve having formed therein a throttling position and a communication position and normally held in the throttling position and being interlocked with the operation of the steering valves, whereby the selector valve is changed-over to its co

Abstract: A hydrostatic transmission in which a hydraulic pump and motor are in a generally U-shaped arrangement with a fluid transfer manifold extending between the pump and the motor. The pump is driven on one side of the manifold by the drive motor of the vehicle on which the transmission is used, and a drive shaft from the motor extends through the manifold, to power the drive wheels on the other side of the manifold. A housing surrounds the pump, motor and manifold and contains hydraulic fluid for the operation of the transmission. Servo controls for the pump and motor are located on the outside of the housing, and a control cover has preloaded servo pistons which properly adjust the servo control when the cover is attached to the housing. A charge pump for the servo controls is in the manifold, and rigid tubular conduits extend between the charge pump and the control cover.

Abstract: A fluid control circuit includes a source of pressurized fluid (10) adapted for connection to a hydrostatic transmission (23) upon actuation of a vent control valve (16). The vent control valve (16) is connected to a control and preconditioning valve (17) which functions to ensure that a control lever (14) is in its "vent" position upon starting of an engine and provides for the continuous preconditioning of the control circuit subsequent to such start-up. The control circuit is relatively non-complex in structure and function and does not require positioning of the control lever (14) in a special reset position upon shifting thereof between its "run" and "vent" positions.

Abstract: A fluid control cirucit for selectively varying the displacement of a variable displacement pump (P), such as the type employed in a hydrostatic transmission, comprises a primary control circuit connecting a pressurized fluid source (10) with the pump (P) and adapted to be actuated to selectively vary the displacement of the pump (P) between minimum and maximum values. A separate override control circuit is connected to the primary control circuit to override it to selectively vary the displacement of the pump (P).

Abstract: A valve to provide a controlled loss of hydraulic fluid from a closed loop hydrostatic transmission. A method of converting a bleed-off valve from one sensitive only to loop pressure to one sensitive to both loop pressure and charging line pressure. A pressure sensitive surface in flow communication with charging line pressure is used to position the valve to shut off flow in the event that charging line pressure is lost. In the event that charging line pressure and loop pressure are normal the valve provides a controlled bleed of hydraulic fluid. Finally, in the event that loop pressure becomes unacceptably high, flow is shut off.

Abstract: A work vehicle comprising a stepless hydraulic speed change apparatus, a radiator for cooling hydraulic fluid for the said apparatus, a hydraulic cylinder for actuating a work implement, and a hydraulic pump provided with a suction portion. A return flow path is provided for supplying hydraulic fluid from the radiator to the suction portion of the oil pump.

Abstract: A hydraulic controller for a hydrostatic transmission to control a number of functions of a variable displacement pump or motor of the transmission. A valve includes a spool biased in one direction by a spring and in the opposite direction by fluid pressure in a chamber communicating with the charge pump. A variable orifice communicates the chamber with a drain. The size of the orifice is controlled electrically by a signal representative of swashplate position. Depending upon the pressure of the fluid in the chamber, the valve will directly vary the pressure ported from the charge pump to the standard controller. A needle roller has one end in contact with the end of the spool communicating with the chamber. A high pressure signal is provided via a shuttle valve across the high and low pressure conduits of the transmission to the other end of the needle roller.

Abstract: A hydrostatic transmission having a variable displacement pump whose control element varies the transmission ratio and output direction of the transmission is controlled by a hydraulic servomechanism including a direction-reversing valve and a cylinder connected to this valve. A direction selector acts upon the valve and a mechanical or hydraulic locking mechanism is provided to prevent shifting of the valve until the control element of the pump has been restored to its neutral position before direction change.

Abstract: An automatic control system for a hydrostatic transmission having a control circuit receiving a control flow from a control pump which represents a speed of a prime mover and valve components including a single adjustable valve which creates a delta pressure signal to control the transmission ratio which controls the speed of the prime mover.

Abstract: An automatic control for an automotive-vehicle hydrostatic transmission in which the engine drives a variable-displacement hydrostatic (axial-piston) pump which is connected with the motor by hydraulic lines. The hydrostatic (axial-piston) motor can be connected to the wheels of the vehicle. The control circuit comprises a filling pump, a metering throttle, a reversing valve and an adjusting device. The metering throttle is provided in a bypass between the filling pump and the reversing valve and is connected to the line communicating with the control element. A further throttle is provided in this line and has a diameter/length ratio less than 1.

Abstract: In a radial piston pump-radial piston motor drive system, a centrifugal replenishing pump is provided integral with the pump driving means. The radial-piston pump, radial piston motor, centrifugal replenishing pump, and most of the fluid circuit, including fluid sump are all contained within a unitary housing to provide a compact self-contained pump-motor hydrostatic unit.

Abstract: A control including a control valve and an override valve for use with a variable displacement pump or motor unit having a pair of strokers into and out of which fluid must be directed to vary the displacement of the unit. The control valve ports fluid from a high pressure source to a first control passage and from a second control passage to a low pressure source, reverses said flow, and terminates said flow. The override valve is interposed between the control passages and the strokes and defines a pair of override passages therein used to direct fluid from one control passage to one stroker and from the other stroker to the other control passage. The override valve is selectively movable between a first position directing such flow therethrough and a second position in which such flow is terminated between the control passages and the strokers.

Abstract: A constant pressure at the output of a pressure regulator is adjusted to and maintained at a required value by hydraulic remote control of a sliding valve in operative association with a control cylinder responsive to actual pressure conditions. The position of the piston of the control cylinder is determined both by a pilot pressure and by the pressure prevailing at the output of the regulator.

Abstract: A hydraulic speed change gear designed to automatically control its hydraulic circuit pressure to be held at all times at a substantially constant level irrespective of the loading condition so as to enable the pressure oil in the hydraulic circuit to be used as a pressure source for other various hydraulic equipment. To this end, the gear includes a fixed displacement hydraulic pump adapted to be driven by an input shaft, a variable displacement hydraulic motor having an output shaft, a closed hydraulic circuit connecting between said pump and said motor, a hydraulic supply pump drivably coupled to said input shaft, a supply passage connected with a discharge port of said supply pump and with said closed hydraulic circuit through check valves, and an oil pressure control device connected with said closed hydraulic circuit and said supply passage for reducing the oil pressure in said supply passage in proportion to a pressure rise in said closed hydraulic circuit.

Abstract: An arrangement for pumping fluids includes at least one variable-output pump and a drive therefor. An auxiliary pump is also driven by the drive and discharges control fluid at a rate corresponding to the speed of rotation of the drive into a discharge conduit in which a variable flow-through cross-sectional area throttle valve is located. The pressure in the discharge conduit upstream of the throttle valve controls the displacement of a control slide between the two end positions thereof in one of which the control slide controls the variable-output pump so as to increase the output thereof, while in the other of such positions of the control slide the pump is controlled so as to reduce the output thereof. The throttle valve is responsive to the pressure in the discharge conduit, but can be arrested in any position thereof when the drive is overloaded so that the flow-through cross-sectional area thereof is fixed, which results in a decrease of output of the variable-output pump when the drive is overloaded.

Abstract: A safety device for hydraulically driven vehicles including a hydraulic motor for driving the vehicles, a variable displacement pump for supplying fluid to said motor, a servo control mechanism for controlling displacement of said variable displacement pump, an additional pump for supplying fluid to said servo-control mechanism, and a servo valve provided between said additional pump and said servo control mechanism for selectively communicating said servo control mechanism with said additional pump.Movement of the vehicle is prevented when an engine for driving the pumps is running while a shift control lever is either at forward movement position or backward movement position.

Abstract: Modifying the lands of a control spool of a control valve to provide pressurized fluid to the destroking servo when the land covers the destroking servo port. The lands of a control spool are provided with notches to allow fluid to flow from the control pressure port of the control valve to the servo ports of the valve. These notches ensure that a flow of pressurized fluid will be transmitted from the control pressure port to the destroking servo port during return of the swashplate to its neutral position. By providing the notches, pressurized fluid is directed to the destroking port when the land of the control spool covers the destroking servo port. This pressurized fluid helps force via the destroking servo the swashplate back to its neutral position.

Abstract: A hydrostatic transmission is provided with a variable capacity pump and a variable capacity motor. A control is operable to operate sequentially the pump and motor. A second control is provided to operate on the pump to override the signal to the pump from the first control without altering the setting of the motor. The first control thus acts as a ratio selector and the second control as a clutch.

Abstract: A hydrostatic transmission for accelerating, driving and braking a high inertia load, such as the swing mechanism of a power shovel or crane, includes an engine-driven swashplate-type variable displacement constant speed reversible main hydraulic pump coupled in a closed loop circuit to a swashplate-type fixed displacement variable speed reversible hydraulic motor. A pair of control lever operated pilot pressure modulated pump displacement control valves selectively direct control fluid from an engine-driven fixed displacement constant speed charge pump to the stroking pistons of the servo control cylinders on the main pump to thereby control motor direction and speed. The charge pump also supplies replenishing fluid to the main pump/motor circuit through replenishing check valves.

Abstract: A hydrostatic unit of the type contemplated by the present invention includes one or more pump and motor combinations interconnected by means of a conventional closed loop. Controls for the hydrostatic unit include a speed control and vent valve assembly as well as a venturi manifold which functions to normally establish a selected pressure differential in a pair of supply conduits for determining instant operating conditions for the transmission. In order to automatically regulate displacement of each pump unit in response to prime mover speed, an underspeed actuator valve unit includes a piston which is hydraulically responsive to the differential pressure in order to adjust operation of a lever which controls displacement of the pump unit. A part throttle control valve prevents the underspeed actuator from reducing displacement of the pump unit when speed of the prime mover is reduced by a manual throttle control.

Abstract: A normally closed solenoid valve operates conjunctively with a two position pilot valve to limit the amount of engine braking through the drive train of a vehicle by reducing the drive relief valve setting in the disengaged side of a hydrostatic transmission. A second normally closed solenoid valve operates a second two position pilot valve to modulate the rate that the forward drive relief valve in the engaged side of the transmission hydrostatic drive loop permits drive pressure to build up as the vehicle is started in motion. An electrical switch on the transmission control rod initiates activation of the normally closed solenoid valves when the vehicle operator selects a direction of travel.

Abstract: A hydrostatic unit of the type contemplated by the present invention includes one or more pump and motor combinations interconnected by means of a conventional closed loop. Controls for the hydrostatic unit include a speed control and vent valve assembly as well as a venturi manifold which functions to normally establish a selected pressure differential in a pair of supply conduits. In order to automatically regulate displacement of each pump unit in response to both engine or prime mover speed and instant load conditions, an underspeed actuator valve unit is hydraulically responsive to the differential pressure in the two conduits and also to changes in output pressure developed by the pump unit.

Abstract: Hydrostatic transmission having a crossover which is provided with check valves. The check valves are automatically controlled by a series of power chambers that respond to different hydrostatic pressures.