Abstract: A hydraulically-operated support device for semitrailers is disclosed comprising a hydraulic cylinder semitrailer support and a pump subassembly having three independently operable pumps for generating and controlling the hydraulic operating pressure. The hydraulic cylinder semitrailer support has an extending piston in an extending cylinder, in the bottom end of which is formed a load-raising cylinder for a load raising-piston. A first annular space is formed between the extending piston and the extending cylinder and a second annular space is formed between the load-raising piston and the load-raising cylinder. The annular spaces allow application of pressure in the retraction direction. The pump subassembly comprises an extending pump acting on the extending piston, a load-raising pump acting on the load-raising piston and a retracting pump acting on the annular spaces.

Abstract: A hydraulic four-wheel drive apparatus for driving by a hydraulic motor four wheels: steering wheels and driving wheels, in which the steering wheels are driven by a variable capacity motor for the steering wheels and a front differential gear unit, and the driving wheels are driven by a fixed capacity motor for the driving wheels, so that, when a vehicle turns, a swash plate of the variable capacity motor associates with operation of a steering handle, thereby accelerating the speeds of steering wheels.

Abstract: A dual hydraulic motor system where motor wobblers are mechanically linked and the motor outputs are torque summed, is controlled by a three position dual valve assembly. Each valve assembly is controlled by pilot pistons that are mechanically linked to provide three functions, one being normal operation, a second where one motor must be shut-off and its load on the system is minimized and the third where both motors are shut-off and significant drag is then provided. These functions are implemented by a separate spool in each valve which has three independent stable positions.

Abstract: A drive control system, which is suitable for use in a hydraulic machine, is equipped with an electric lever device having a manipulation lever and a potentiometer for generating an electrical manipulation signal corresponding to the degree of each manipulation of the lever, a control valve connected to a hydraulic circuit adapted to actuate a hydraulic actuator, and a controller unit equipped with a main controller for receiving the manipulation signal and computing a control signal for the control valve on the basis of the manipulation signal and an output device for generating an electrical actuation signal corresponding to the control signal.

Abstract: Hydraulic circuit in an industrial vehicle, which comprises: a cargo-steering hydraulic circuit, flow rate of which is large and pressure of which is high; and a booster hydraulic circuit, flow rate of which is small and pressure of which is medium; the hydraulic circuits being independent from each other; the cargo-steering hydraulic circuit being communicated with a hydraulic pump, flow rate of which is large and pressure of which is high; and the booster hydraulic circuit being communicated with a hydraulic pump, flow rate of which is small and pressure of which is high.

Abstract: A hydraulic transmission, in particular for an automotive drive system including a combustion engine comprises at least a pair of hydrostatic pumps and at least a pair of hydrostatic motors each pump and/or motor having the same size or different size with a constant or adjustable through-put. Automatically actuated clutches are provided to connect the pumps to the engine and to connect the motors to a load. A variety of transmission ranges is obtained by activating selected ones of the individual pumps and motors by actuating corresponding clutches. Therefore, the combustion engine may be operated under conditions in which fuel comsumption is as low as possible.

Abstract: Separate left and right hydrostatic transmission (15) for controlling rotation of left and right final drive wheels (11) of a working vehicle independently are disposed laterally inwardly of the drive wheels in a vertical posture such that, while an input shaft (23) extends upwardly, an output shaft (24) extends downwardly. To each of the hydrostatic transmissions is attached a L-shaped gear box (16) which extends over lower and outer sides of the hydrostatic transmission and supports the axle (17) of final drive wheel at its upstanding portion. within the box is housed first and second reduction gear trains which form a L-shaped transmission path between the output shaft and axle.

Abstract: A multiple stage rotary fluid device enclosed within a housing containing a working hydraulic fluid. An axially extending shaft is adapted to be secured to a source of power at one end. Fluid within the housing is directed across a control valve to an initial pump stage driven by the shaft. Pressurized fluid from the initial pump stage is directed to a hydraulic motor having a rotor which is rotatably driven through a planetary gear arrangement within an accentric housing. The pump housing surrounding the motor and pump is driven in a direction opposite that of the main shaft through a bevel gear arrangement driven from the axial shaft. Fluid is discharged through peripheral exhaust ports and the reservoir.

Abstract: A hydraulic circuit for a large crane furnished with a counterweight carriage detachably connectable to the swivel unit of the crane.

Abstract: A control system for the boom and bucket operation system on a front end loader that includes an unloader valve responsive to pilot valve pressure to bypass hydraulic fluid pumped by an auxiliary pump to the reservoir while maintaining the primary pump supply to a loader valve which supplies pressure to the boom and bucket cylinders in response to the operation of pilot valves. The unloader valve bypasses the auxiliary pump flow when the pressure is below a predetermined value and when the pressure is above a second higher predetermined value.

Abstract: A hydraulic operated control system for remotely operating a walk-behind soil compactor. A remotely operated three-position valve is connected to the pressure line of the hydraulic system of the soil compactor and serves to control the flow of hydraulic fluid to opposite ends of a hydraulic cylinder unit that is operably connected to a hydraulic pump which operates the speed and direction control for the compactor. The cylinder unit includes a piston that is slidable within the cylinder and the piston is biased to a neutral position by springs. Through remote operation of the valve, hydraulic fluid will be directed to either end of the cylinder to provide direction and speed control for the compactor. A deadman switch is located on the remote control panel and manual release of the deadman switch will open the hydraulic circuit between the opposite ends of the cylinder to prevent fluid from being directed to the cylinder and will enable the springs to return the cylinder to a neutral no speed position.

Abstract: A hydraulic drive system utilizes four hydraulic motors arranged in mechanically coupled pairs with one motor from each pair always series hydraulically connected to one motor from the other pair. The other motors are selectively coupled parallel with each other or in series with the series connected motors. The combination of mechanical and hydraulic coupling provides an efficient drive system designed specifically for, but not limited to, the motor grader apparatus. The improved drive system herein disclosed provides both high speed-low power and low speed-high power operational modes and is capable of continuous operation in either mode. The improved drive system also provides superior control characteristics due to the hydraulic motor series lockup arrangement. The combination of mechanical and hydraulic coupling provides high power with good control or high speed with little heating of the hydraulic fluid.

Abstract: A drive system having two hydrostatic gears (1, 2) driven by a common driving motor or by a plurality of driving motors having a fixed speed ratio, each having a pump (5, 6) and a hydraulic motor (7, 8) and in which the delivery or intake volume setting of the pumps (5, 6) and/or the hydraulic motors (7, 8) is performed by hydraulic servomechanisms (13, 14) of which the control pressures in the control pressure lines (23, 24) can be varied as desired either independently or together by means of pressure indicating valves (26) connected to each of the gears (1, 2) and supplied by an auxiliary source of pressure (9, 10) is arranged so that, at least on starting, the outputs of the gears (1, 2) are as nearly as possible equal.

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 plurality of mechanically coupled secondarily controlled hydrostatic machines with variable volume are connected to a line with impressed system pressure fed by a primary unit. By reducing the variable volume to 0 in individual hydrostatic machines the remaining machines are subjected to a higher torque which results in a greater pivot angle of the remaining secondary units. As a result the efficiency and controllability are improved. The changeover is effected in dependence upon an upper and lower switching point corresponding to the pivot angle of the unit remaining in engagement.

Abstract: A control block is made up of a plurality of directional valves which serve to actuate a plurality of hydraulic drives to which in some cases a different pressure is to be supplied. For this purpose two pressure-limiting valves adjustable to different pressures are provided, the valve adjustable to the lower pressure being connected to the last valve unit. This gives a simple construction and substantial freedom in the association of the drives.

Abstract: A hydrostatic drive with an adjustable pump and several consumers is provided in which one or several consumers simultaneously can be selectively connected with the pump, in which case the connection to a consumer can be effected by an arbitrarily actuable control valve having a throttling effect in the intermediate positions, where the loading of the adjusting element of the pump is controlled by a pump adjusting valve, which in turn is regulated by the pressure differential arising at the regulated control valve so that it is regulated to a constant pressure differential, where the highest prevailing pressure in a line between the regulated control valve and the regulated consumer is conveyed through a control pressure line to the control pressure chamber on the spring side of the pump adjusting valve and where a pressure limiting valve is connected to the pump delivery line and provided on the spring side with a control pressure chamber connected with the control pressure line (load-sensing signal line).

Abstract: A hydraulic power system is disclosed which comprises an internal combustion engine having a speed regulator, and which serves to drive a hydraulic system including a pump and a consumer or load. A throttle valve is positioned in the hydraulic system, and the throttle valve is connected to an adjustable controller, such that the volume flow rate to the consumer is proportional to the control signal delivered to the throttle valve by the controller. The same control signal of the controller is also delivered to the speed regulator of the engine. In one disclosed embodiment, the hydraulic system includes a plurality of consumers connected to a common pump, and each consumer includes an associated throttle valve and controller. Also, means are provided for weighting the several control signals from the controllers, and summing the weighted signals so that a composite adjusting signal is delivered to the speed regulator of the engine.

Abstract: A tree-harvester operating system for controlling in particular the tree-feeder motors (5), the crosscut saw (6) and the cylinder (18) operating the function of the feeder and the limbing blades, especially in grapple processors. A simple operating system has been achieved by taking advantage of a two-direction feeding of pressurized oil by means of two delivery lines (2) and (3). By preventing the rotation of the tree-feeder motors (5) and by allowing at this time only one flow direction of pressurized oil to the crosscut saw, it has thus been possible to utilized the pressurized oil drive opposite to this flow direction of the saw (6) separately for the cylinder (18) which operates the function of the feeder and the limbing blades, the direction of movement of the cylinder (18) depending on the position of valve (15).

Abstract: In a hydraulic system loaded on a working vehicle, an oil pump is fixedly secured to a casing block of a transmission system disposed on a vehicle body as separated from an engine, an input shaft of this oil pump is drivably coupled to an input shaft of the aforementioned transmission system, and a clutch is interposed between the input shaft and a transmission mechanism of the transmission system. Preferably, a control valve is fixedly secured to the oil pump, and a delivery port of the oil pump is directly coupled to an inlet of the control valve. Furthermore, so improved structures of a hydraulic switching valve adapted to be disposed on an outlet side of the control valve is proposed.

Abstract: A dual pressure source, or selectively alternative high pressure source, control system for a variable displacement hydraulic unit servo mechanism wherein normal control of the unit is provided by the low pressure source, such as a transmission charge pump, and wherein a high pressure source of control fluid with a restrictive orifice is provided to initiate servo movement, especially under conditions generating high internal friction. The flow restrictive orifice generates a pressure drop in a high pressure control line once the servo mechanism starts to move, inducing flow through such line. Thus, the control system provides a momentary source of high pressure fluid but permits control rate changes which are substantially independent of the hydraulic unit working pressure. Preferably, the high pressure source is a shuttle selected highest pressure of a transmission main loop incorporating the hydraulic unit.

Abstract: A hydraulic drive system for a counterweight dolly in a counterbalance type crane having a crane body provided with a lower travelling structure an upper swivelling structure and the counterweight dolly connected to the rear portion of the upper swivelling structure through a connecting member, characterized by including a swivelling hydraulic motor for swivelling the upper swivelling structure of the crane body; a swivelling control valve for controlling the pressure of hydraulic oil to be fed to the swivelling hydraulic motor; a hydraulic circuit for swivelling operation which controls the amount of operation of the swivelling control valve; a hydraulic motor for the counterweight dolly which drives each wheel of the dolly; a dolly control valve for controlling the pressure of hydraulic oil to be fed to the hydraulic motor for the counterweight dolly; and a control circuit for actuating the dolly control valve in accordance with an operational pressure of the hydraulic circuit for swivelling operation and t

Abstract: A hydraulic drive system for counterweight dolly in a counterbalance type crane, including dolly driving wheels supported vertically movably through wheel supporting hydraulic cylinders at the lower portion of the counterweight dolly which is connected to the rear portion of a crane body; a wheel driving hydraulic motor connected to each of the wheels; a support pressure detecting mechanism for detecting a support pressure for each wheel supporting hydraulic cylinder, the support pressure detecting mechanism being provided in a drive circuit for the cylinder; and a mechanism for controlling the driving pressure for the wheel driving hydraulic motor in accordance with a detected value provided from the detecting mechanism.

Abstract: An apparatus for controlling the fluid flow delivered to work elements of a work vehicle. In the operation of hydraulic work vehicles, when quick or multiple implement movement is required, the fluid pumps often are requested to surpass their capability in providing fluid flow to the work elements. A flow-limiting situation then occurs wherein some of the work elements are not receiving the requested flow and therefore cannot perform their requested functions. To solve this problem, the total available flow and the total requested flow from the pumps are monitored. If the total requested flow is not great enough to cause a flow-limiting situation, the operators demands are communicated to control valves which control fluid flow to the respective work elements. However, if the total requested flow is greater than the total available flow, the operators demand signals are "scaled down" in order to prevent a flow-limiting situation.

Abstract: An oil pressure control system for a power transmission which includes an oil pump, a regulator valve, an inching valve, a selector valve, a change over valve, a modulator valve, a clutch servo, a first oil passage for communicating the oil pump with the selector valve via the regulator valve and the inching valve, a second oil passage for communicating the selector valve with the change over valve and the clutch servo, a third oil passage for communicating the change over valve with one end of the modulator valve and a fourth oil passage for communicating the first oil passage located between the inching valve and the selector valve with the other side of the modulator valve. The system permits a smooth, controlled operation of the clutch servo.

Abstract: The invention contemplates a hydraulically operated twin-cable suspension for a clamshell or the like load-handling device. In a preferred embodiment, a charged accumulator is effectively a counterweight and is the source of all hydraulic fluid needed for the full range of actuation of two traction cylinders, one for each of the respective cables. Two power integrators are employed: one is interposed between the accumulator and one of the traction cylinders, and the other is interposed between the accumulator and the other traction cylinder; hydraulic control interconnections between the respective integrator circuits enable load sharing by both cables and simplified single-lever control of plural clamshell functions, including (a) an automated closing dig into loadable material and (b) a quick opening for load discharge.

Abstract: A hydraulic control system for a downhole sidewall coring tool having first and second power hydraulic systems in which changes in pressure drop in a portion of the first hydraulic system adjusts a control valve to change the pressure in a part of the second hydraulic system. Means are provided to adjust the operation of the control valve as a function of viscosity change in the hydraulic fluid caused by change in ambient temperature.

Abstract: A load sensing priority flow control system is disclosed of the type including an engine-driven pump (11), a load sensing priority flow control valve (15), a priority load circuit (steering control valve (17) and steering cylinder (21)), and an auxiliary load circuit (19). Disposed between the excess flow output port (45) of the priority valve and the auxiliary load circuit (19) is a bypass valve arrangement (55) including a bypass valve member (57) which is biased by a downstream pressure signal (61) and spring (63) to a first position in which the auxiliary load circuit is communicated to the reservoir, to prevent loading the system and stalling the engine when the engine speed and flow from the excess flow port (45) are below a predetermined minimum. As engine speed and flow from the port (45) increase, an upstream pressure signal (59) biases the bypass valve toward a second position in which the auxiliary load circuit is blocked from communication with the reservoir, and can be pressurized and actuated.

Abstract: A retractable in-row tiller device is adapted for mounting on a movable vehicle and for tilling the ground around and between objects in a row. An outrigger arm with a rotary tiller mounted on its distal end is retracted inwardly and extended outwardly by a trapeze-type control arm which amplifies the velocity and magnitude of reciprocal motion produced by a hydraulic ram to move around and avoid objects encountered in the row. Both manually and automatically operable controls are included respectively to allow an operator to retract and extend the tiller out of and into the row as desired and to cause the tiller to be retracted and extended out of and into the row automatically upon encountering an object in the row. Manual control is also provided for the operator to override the automatic retraction control.

Abstract: A piston type expander/prime mover utilizes a plurality of pairs of cylinders mounted on a rotatable cylinder support. Each cylinder has an open end and a closed end and each pair of cylinders has their open ends disposed in spaced, opposed relationship. A pair of pistons respectively cooperate with the pair of cylinders, and each piston has a connecting rod pivotally secured thereto and projecting through the open end of the respective cylinder. The two ends of the connecting rods are in turn pivotally connected to a lever arm which is secured to the movable element of a first unidirectional (over-running) clutch which has its stationary element secured to a stationary shaft. A first load transmitting element is secured to the rotatable element of the unidirectional (over-running) clutch. Valving is provided in the closed end of each cylinder to permit a charge of pressured gas to be introduced into such closed end as the respective piston approaches such closed end.

Abstract: A composite hydraulic system for a work vehicle which has two separate hydraulic circuits. Included in the composite system are three pumps, two of which supply the two circuits on the vehicle. A third pump transfers hydraulic fluid between the two hydraulic circuits. An engine operates all three pumps simultaneously and means are provided whereby the third pump under certain conditions operates as a motor to provide regeneration.

Abstract: A vehicle control system has a system part 5 with a pump 6 feeding an open centre valve 4 which controls power assistance for vehicle steering. A second system part 11 has a pump 16 feeding an accumulator 13 and a closed centre valve 10 which controls operation of a clutch or brake booster 2. The pumps 6 and 16 are simultaneously driven by a motor 18. A by-pass valve 21 in conduit 20 is responsive through a pressure transducer 22 and an electrical control unit 19 to pressure in the accumulator 13 so that when the accumulator pressure attains a predetermined value the by-pass valve 21 opens communication between the output from pump 16 and a reservoir 7 to relieve the load on the motor 18. A pressure regulating valve 23 is provided in the steering system part 5.

Abstract: A control drive is provided for the drive of a vehicle, whose steering is effected by a differential driving of the drive wheels of the two sides of the vehicle, where the drive wheels of each vehicle side are driven through a hydrostatic drive unit, whose final control element is connected with a servo piston capable of sliding in an operating cylinder and is acted upon from both sides, in which case the servo piston is acted upon from one side for controlling the travel speed and the control pressure determining the travel speed is reduced for effecting a turn on one side of the vehicle for large turning radii, and for smaller turning radii a pressure is additionally built up on the opposite side of the servo piston, the said pressure being derived from the control pressure determining the travel speed on the other side of the vehicle.

Abstract: A hydraulic circuit arrangement for controlling a plurality of actuators connected to a high pressure line of a main pump parallel to each other has a sequence valve interposed in a line bypassing from the high pressure line to a reservoir. In the bypass line a throttle is interposed between the sequence valve and the reservoir. A regulator for controlling the displacement of the main pump is connected to the bypass line between the sequence valve and the throttle at a pilot chamber thereof. An auxilially pump is connected to the high pressure line parallel with the sequence valve. A delivery line of the auxilially pump has a bypass line interposed with a relief valve. The main pump may be switched to unloaded condition for the stand-by condition of the actuators and to loaded condition for the operation condition of the actuators.

Abstract: A hydrostatic transaxle assembly (11) is disclosed including a central manifold portion (15) and left and right axle assemblies (17 and 19). The axle assemblies include hydraulic motors (37 and 39) connected in parallel through the manifold 15 to the output of a variable displacement pump (13). The transaxle assembly includes a differential mechanism (111), including fluid displacement mechanisms (113) and (115) of which the inner rotors (127) are connected for common rotation by a shaft (117). The differential mechanism (111) includes a selector valve (119; 161) which can either interconnect left and right passages (33b and 35b), downstream of the mechanisms (113 and 115) to permit normal differentiating action, or can prevent such communication between the passages (33b) and (35b) to cause limited differentiating action of the transaxle assembly.

Abstract: A control drive is provided for the drive of a vehicle, whose steering is effected by a differential driving of the drive wheels of the two sides of the vehicle, where the drive wheels of each vehicle side are driven through a hydrostatic drive unit, whose final control element is connected with a servo piston capable of sliding in an operating cylinder and is acted upon from both sides, in which case the servo piston is acted upon from one side for controlling the travel speed and the control pressure determining the travel speed is reduced for effecting a turn on one side of the vehicle for large turning radii, and for smaller turning radii a pressure is additionally built up on the opposite side of the servo piston, the said pressure being derived from the control pressure determining the travel speed on the other side of the vehicle.

Abstract: A control system for a hydraulic vehicle having a pair of bidirectional travel motors driven by respective pumps via respective travel valves, and implement actuators, including a swing motor, driven by the pumps via two parallel connections of pilot-operated implement valves. For making possible the straight travel of the vehicle, either forwardly or rearwardly, while any of the implement actuators is being driven by either pump, a straight travel valve is provided for the on-off control of communication between the forward travel ports, and between the rearward travel ports, of the two travel motors. Normally held closed under spring pressure, the straight travel valve is pilot opened by a series connection of two straight travel control valves, which delivers pilot control fluid to the straight travel valve when the travel valves are both hand operated to set the two travel motors into rotation in the same direction.

Abstract: A control valve assembly having a plurality of control valves, each including a pair of logic valves, with each of the logic valves having a pump port, a work port and a pilot port. The control valve assembly has a housing, and a pair of hydraulic fluid passageways arranged in the housing in side-by-side relationship. Each pair of logic valves, constituting one of the control valves, are arranged in the housing in such a manner that they are located in opposed relationship to each other in a direction substantially perpendicular to a direction in which the hydraulic fluid passageways extend. The pump ports of the logic valves are in communication with the associated hydraulic fluid passageways. The work ports of the logic valves are oriented in a direction substantially perpendicular to both the direction in which the hydraulic fluid passgeways extend and the direction in which the pair of logic valves are arranged.

Abstract: A hydraulic circuitry for a backhoe in which a hydraulic motor for driving one of right and left crawlers and a hydraulic cylinder for vertically oscillating a working arm assembly are connected in parallel to each other to a first pump through a multiplex valve assembly having a first center bypass, and a hydraulic motor for driving the other crawler, a hydraulic motor for slewing a platform, a hydraulic cylinder for flexing and stretching the arm assembly, a cylinder for actuating a bucket and a cylinder for actuating a dozer are connected in parallel to one another to a second pump through a further multiplex valve assembly having a second center bypass. The invention provides a circuit to permit fluid pressure from the first pump to enter the circuit connected to the second pump to provide confluence therein, when the dozer actuating cylinder connected to the second pump, for example, is operated while the backhoe is running.

Abstract: The known swash plate type oil hydraulic piston pump is improved in that three delivery slots each extending over an angular distance of about 60.degree. are formed in a valve plate along one circumference concentric with a rotary cylinder block at an angular interval of 60.degree. and the number of piston-cylinder units provided in the cylinder block is chosen to be a multiple of 6. Pressurized oil delivered through a center delivery slot is fed to one hydraulic actuator, and pressurized oil delivered through the delivery slots on the opposite sides of the center delivery slot is jointly fed to the other hydraulic actuator, whereby variations of flow rates of the pressurized oil fed to the respective hydraulic actuators can be minimized.

Abstract: A jacking mechanism for jacking a well casing or other well pipe vertically, and including a hydraulic control system in which a reversible variable displacement pump acts in one condition to deliver pressure fluid in parallel with another pump to the lower end of a jacking cylinder to actuate the piston thereof upwardly, with fluid discharging from the upper end of the cylinder to the variable displacement pump and being metered therethrough to regulate the rate of upward movement of the piston. In a second condition of the apparatus, flow through the variable displacement pump is reversed to lower the piston, and a variable restriction valve regulates discharge of fluid from the lower end of the cylinder to act with the variable displacement pump in regulating downward movement of the piston and supported pipe.

Abstract: A hydraulic driven electric generator and air conditioning system for simultaneously generating controlled quality electrical power and producing air conditioning in a desired area has a variable displacement hydraulic pump for pumping a hydraulic fluid is driven by a prime engine means. The pump is hydraulically connected to a fixed displacement hydraulic motor which is powered by the fluid flow. The first motor drives an electrical generator means for generating electricity having a rotating blower fan mounted within a generator housing. A second hydraulic motor is hydraulically connected to the output of the first motor and is used to provide power to an air conditioning means. Means monitoring the passage of blower teeth of the rotating blower fan produces an electric output responsive to changes detected in the rotation of the blower fan.

Abstract: A hydraulic drive system for civil engineering and construction machinery having at least one hydraulic pump driven by a prime mover, at least one hydraulic actuator connected to the hydraulic pump, and at least one hydraulic cylinder, the hydraulic actuator and hydraulic cylinder being adapted to operate movable members. The hydraulic drive system is provided with a hydraulic pump-motor coupled to the prime mover, a first conduit for connecting the hydraulic pump-motor to one side of the hydraulic cylinder which moves a movable member in a direction in which the potential energy thereof increases in magnitude upon feeding of liquid under pressure thereinto, a second conduit for connecting the other side of the hydraulic cylinder to a reservoir, and an arrangement for controlling the hydraulic pump-motor in such a manner that it functions as a motor when the operator operates the system to move the movable member in a direction in which the potential energy thereof is reduced in magnitude.

Abstract: A four piston hydraulic pump driven by a four cylinder free-piston Stirling engine has four stepped pistons operating out of phase in pairs. The hydraulic fluid pumped between the hydraulic cylinder can be tapped for hydraulic power. The stepped pistons give the option of utilizing low flow/high pressure, or high flow/low pressure. The non-utilized flow ensures that the timing between pistons will always remain correct. Since the arrangement is symmetrical, it remains balanced.

Abstract: A hydrostatic drive system for an excavator is provided having a primary energy source on the excavator, at least one pump installed in a housing for supplying several consumers, a connection between each pump and consumer effected through at least one control block and at least one connection from a consumer through a rotary transmission to the pump and wherein at least some of the pumps, distributors, control blocks and rotary transmission are joined into a common block.

Abstract: A torque transfer apparatus includes one or more externally powered energy pumps having a plurality of piston and follower arrangements. The pistons are attached to crankshafts, while the associated followers are controlled by a timing chain driven camshaft. The energy pumps are provided with belt drives to power one or more oil pumps, and the oil pumps provide pressurized oil between the followers and pistons so as to improve power transfer efficiency. Additionally, return lines are provided which permit the pressurized oil to be returned to the oil pump during a return stroke of the associated pistons.

Abstract: A control is provided for the drive of a motor vehicle with differential-speed steering and with a hydrostatic power transmission unit on each side of the vehicle, where the adjusting element of each of the two power transmission units is provided with a spring-loaded adjusting piston that can be acted upon by control pressure, in which case two pairs of control pressure pick-offs are provided, of which two are assigned to forward and backward movement and the other two are assigned to cornering, where a pressure-dependent switchable pilot valve is installed in the connecting line between a control pressure pick-off assigned to a cornering direction and the adjusting element of the assigned power transmission unit, the pilot valve connects this control pressure pick-off assigned to the cornering direction with a specific pressure chamber of the adjusting element of the power transmission unit on the side of the vehicle on the inside of the curve, so that through actuation of the control pressure pick-off dete

Abstract: A hydraulic system for controlling hydraulic motors for driving a tracked vehicle which circuit utilizes a single manual control lever to control valve control units to direct pilot pressure to actuate bi-directional valves that control the direction of movement of the hydraulic motors.

Abstract: A sluing mechanism driven by one or more electric or hydraulic motors, for excavating or bulk handling machines comprises a pivotable discharger boom mounted on a rotary support or turntable, and a coaxially pivotable superstructure carrying further equipment. The sluing drives of the two coaxially pivotable parts of the machine are connected to each other in such a way that upon pivoting the superstructure, the discharger boom does not follow this pivotal motion. The sluing drive of the discharge boom is designed as a superposed gear and connected to a drive motor for separately sluing the discharger boom. The turntable is provided with a second discharger sluing gear which is driven by a motor having a weaker characteristic than the drive motor or motors for sluing the superstructure. The characteristic of the motor driving the second discharger sluing gear may be adjustable.

Abstract: An hydraulic drive apparatus for use in downhole tools is described. The apparatus provides rotational and translational movement to a cutting tool element disposed in a downhole tool or sonde automatically adjusting advancing motion of the cutting tool to the rate of rotational movement or cutting. The apparatus is controllable from the surface through a wireline and is capable of operating in various modes to facilitate unjamming.