Abstract: An arrangement is described for controlling a winch used in mining machinery, wherein the direction of operating a winch and speed thereof are controlled by changing the position of a control element of a fluid pump for supplying a fluid into a fluid pressure recirculating circuit, by a device incorporating the fluid pressure recirculating circuit and a control circuit. The arrangement is characterized by feeding ON/OFF signals for giving instructions of a position to a control element, by a bi-polar pulse generator. Pulse from the bi-polar pulse generator are fed to a reversible BCD counter by pressing push buttons, and comparing a voltage generated via a D/A converting circuit from the reversible BCD counter with a voltage generated from a potentiometer coupled to the control element according to the position of the control element to be selected, thereby controlling the instruction of the position of the control element; and setting a speed of the winch by pressing the push buttons.

Abstract: A hydrostatic transmission coupled with a gear transmission for operating a motor vehicle driven by an internal combustion engine has its accelerator pedal connected to the throttle valve of the engine and to the servovalve of the stepless hydrostatic transmission via an engine characteristic storage which modulates the accelerator travel signal applied to the servovalve to optimize the fuel consumption. The servovalve also receives input from an electric signal comparator which compares the engine speed with an output signal from the output unit of the hydrostatic transmission or the output shaft of the gear transmission.

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 hydraulic circuit is provided to prevent overspeeding the prime mover powering a hydrostatic transmission. The hydrostatic transmission includes a hydraulic motor fluidly coupled to a hydraulic pump. The hydraulic pump is driven by the prime mover and the hydraulic motor drives a rotational load. The hydraulic pump includes a swash plate tilted by a servomechanism. The servomechanism receives hydraulic fluid from a pump powered by the prime mover. A valve is operated to shut-off the hydraulic fluid to the servomechanism in the event that the pressure in either of the two conduits joining together the hydraulic pump and the hydraulic motor exceeds a pre-set maximum value or if the pressure in an auxiliary line exceeds the same pre-set maximum value or if the sum of the two pressures exceeds the pre-set maximum value.

Abstract: In a crank press having a pedestal and a rotatable crank shaft journaled thereon and connected to a reciprocal top platen guidably mounted on the pedestal to form work pieces, the improvement which comprises a hydraulic motor mounted on the pedestal having a reversible drive shaft connected to the crank shaft, and a hydraulic transmission connected to the hydraulic motor. The transmission includes a pump assembly connected to a reservoir for delivering the pressure fluid selectively under the control of a servo directional valve in a closed hydraulic loop to the hydraulic motor for selective forward and reverse drive together with a safety control to automatically neutralize the pump assembly and control automatic braking of the hydraulic motor drive shaft.

Abstract: A control for a variable displacement pressure compensated pump in which pressurized control fluid regulates the setting of a sequence valve to set the maximum output pressure of the pump and also set the displacement of the pump. The sequence valve is a two-stage device which utilizes a sequence poppet stage and cone stage. When working fluid pressure exceeds the setting of the sequence valve, the cone stage spills to reduce the displacement of the pump. If the pressure is not reduced fast enough the sequence poppet spills to more rapidly reduce the displacement of the pump.

Abstract: The hydrostatic transmission control system includes a first and second two-position solenoid valve which function to alter the hydraulic fluid parameters as delivered to the servo control cylinders of a variable displacement pump associated with a hydrostatic transmission. Activation of the first solenoid valve instigates a varying of pump displacement. Once the desired pump displacement has been achieved, the second solenoid valve is activated to maintain the desired pump displacement. The deactivation of both solenoid valves results in the hydrostatic transmission seeking and maintaining a neutral mode.

Abstract: A control system is disclosed for a hydrostatic transmission of the type including a prime mover driven variable displacement pump, the displacement of which is controlled by a pair of strokers (28, 30). Flow of pressurized control fluid from the charge pump to one of the strokers, and from the other stroker to tank, is controlled by a main control valve (34). The control system includes an auxiliary control valve (44) defining passages (98, 100, 102) communicating between the lines connecting the main control valve and the strokers. The auxiliary control valve includes an on-off, electro-hydraulic valve (46) which prevents flow through the auxiliary valve in response to an electrical signal in one condition, and permits flow in response to an electrical signal in another condition.

Abstract: A hydrostatic transmission includes a reversible, variable displacement pump having a swashplate actuator controlled by a pilot-operated displacement control valve. A manually operated displacement control lever is manipulated to opposite sides of a neutral position to effect command signals for causing pilot operation of the displacement control valve to control movement of the swashplate in accordance with the command. A neutral control valve is coupled to the displacement control lever and is operated thereby to a neutral position, wherein it connects the swashplate actuator to sump, when the lever is moved to its neutral position.

Abstract: A feathering valve system for modulating the fluid inflow to a selected one of first and second chambers of a movable biased assembly. A controller is electrically coupled to a first and second solenoid operated pilot valve assemblies for selectively (1) maintaining the pilot valve assemblies in a valve closed state without bleed flow through the pilot orifices or (2) supplying a predetermined value electrical signal to either, but not both, of the valve assemblies for actuating one of the assemblies to an open position related to the value of the signal. Fluid under a substantially constant pilot pressure is applied under the poppets of both valve assemblies. Fluid flow is taken from above the poppet of an actuated valve assembly to a respective chamber whereby the movable assembly moves to a position which is a function of the actuating signal value.

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: A hydrostatic converter has at least one hydromotor and at least one pump. The characteristic curve of the pump, which represents the relationship between pressure and stroke volume, has a hyperbolic part. The performance graph of the hydromotor, which represents the relationship between motor driving torque and motor speed, also has a hyperbolic part. A torque controller, including a regulating unit, is associated with the pump for producing a variable auxiliary force for displacing the hyperbolic part of the performance graph of the hydromotor. Automatic, stepless adjustment of the rate of revolution and torque takes place at the hydromotor as a function of the load, in both the full and partial load ranges.

Abstract: A control arrangement for a hydrostatic drive comprises a gear pump driven by an internal combustion engine and supplying fluid to a fluid motor. The control arrangement is constructed in such a manner that even at a high number of revolutions per time unit of the internal combustion engine, the fluid motor may be operated at a low number of revolutions.

Abstract: A system for controlling the operation of a reversible hydrostatic transmission including an engine-driven pump, particularly for a self-propelled utility vehicle such as a forklift truck, comprises a switchover member coupled with a setting lever of the hydrostatic pump which is biased by a pair of counteracting springs into a normal centered position. A shift lever, upon being moved from "neutral" to "forward" or "reverse", causes a displacement of the switchover member into a corresponding off-normal position by a fluidic or electromagnetic directive force generally proportional to engine speed.

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 fluid drive vehicle has an engine speed control, a fluid drive transmission having a fluid actuator device for moving a control element from its neutral position progressively to increase the drive ratio, and a control system which includes a first fluid circuit which has a control valve movable from a neutral fluid blocking position progressively to increase the flow of pressurized fluid from an auxiliary pump to the fluid actuator device. A fluid responsive servo mechanism moves the control valve from the neutral position while a fluid motor is operative to move the engine speed control from an idling position to increase the engine speed.

Abstract: A transmission having a variable capacity pump and motor is provided with an override device which ensures that the motor is at a maximum capacity, and hence maximum torque capability, prior to operation of other protection devices.

Abstract: A rotary shredder for waste materials has a pair of counterrotating cutting shafts, each of which mounts a series of spaced-apart disc-type cutters. The cutters on one shaft extend into the spaces between cutters on the other shaft so that the cutters on the two shafts coact to shred material fed therebetween. The two shafts are driven by a reversible radial piston hydraulic motor through a gear train arranged to rotate one cutter shaft at twice the speed of the other. The hydraulic motor is driven by an electric motor-driven fixed or variable displacement pump. A flow-reversing valve in the hydraulic motor control circuit controls the direction of fluid flow through the hydraulic motor. The reversing valve is electrically actuated automatically by a fluid pressure-operated switch to reverse flow and the direction of rotation of the cutters to prevent jamming whenever fluid pressure in the motor circuit rises to an abnormally high level.

Abstract: A piston pump having a housing and an angularly adjustable swash plate for controlling piston displacement and the flow of fluid discharged from the pump has control means for controllably positioning the swash plate in response to a load pressure.

Abstract: A variable displacement pump having a tiltable swash plate including a pair of servo mechanisms for controlling discharge of pump fluid includes a zero displacement positioner for automatically returning the pump swash plate to a central, neutral position to discontinue pumping action if pump pressure is lost or if linkage controlling one of the servo mechanisms should break or otherwise fail.

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 servomechanism for pump capacity control includes an adjustable throttle of the "nozzle-gate" type formed with two operating slots communicating through two fixed throttles with duct, a source of supply feeding the duct, an input signal converter whose movable element is connected to the gate of the nozzle-gate throttle and a four-slot, five-line distributor whose control spaces are in communication through two fixed throttles with the duct of the source of supply, two operating slots being formed in the adjustable throttle, whereas its operating spaces communicate with the corresponding spaces of an actuating hydraulic cylinder. The latter is connected to the control element and, by a mechanical position feedback, to the gate. The mechanical position feedback is constituted by a bar which is linked to the movable element of the hydraulic cylinder and has a slanted surface. The slanted surface interacts with a spring-loaded pusher, whose springs act on the gate.

Abstract: In a hydraulic system having a plurality of variable displacement pumps driven by a prime mover, each pump has a variable ratio input device connected to a load sensing means. Each variable ratio input device automatically reduces the displacement of its respective pump by the same proportion when the prime mover is overloaded irrespective of the displacement setting of the pump and automatically increases the displacement of its pump by the same proportion up to the set displacement when the prime mover is not overloaded.

Abstract: A hydraulic machine is provided with a control for reducing the capacity of the machine when subjected to excessive pressure.A piston is slidable in a cylinder to define two chambers, the chambers being interconnected by a restrictive passage. One chamber is connected to the pressure line and the other chamber is connected to a relief valve so that in the steady state the pressure in each is equal. When the pressure reaches a predetermined level the relief valve opens and vents the other chamber. The passage prevents flow to the other chamber creating a pressure differential which causes the piston to move along the cylinder and operate the machine control to decrease the capacity thereof.

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 variable displacement hydraulic system includes a charge system having a substantially constant charge pressure, a reciprocating piston type pump having a drive chamber in communication with the charge system, and a control valve regulating the flow of fluid from the charge system to the inlet of the reciprocating piston type pump which is manually movable from a closed fluid blocking position through a first range in which it varies and controls the quantity of fluid flowing to the pump inlet and a second range in which it varies the control of pressure of fluid flowing to the pump inlet at flow rates greater than those obtainable in the first range.

Abstract: A hydrostatic vehicle transmission with a primary and/or secondary part adjustable as to its delivery and its absorption capacity respectively. The hydraulic adjusting elements of said primary and/or secondary part are automatically by spring force adjusted in the direction toward their starting position and are connected to a control circuit which is adapted to be connected to the pressure conduit of a constant delivery pump and is also adapted for controlling the control pressure to be connected to a return line by means of a control member. An adjustable orifice of a limit load control is arranged in the pressure line, which orifice is arranged ahead of the connection of the control member when looking in flow direction. The adjusting member of said limit load control may for instance be connected to the gas pedal or manually operable gas lever of an internal combustion engine for instance a Diesel engine while the hydrostatic vehicle transmission also serves as vehicle brake.

Abstract: A control system comprising an actuator having a fluid responsive member movable in at least first and second directions and two sources for controlling the fluid responsive member. A first of these sources includes a servo pump which pumps fluid from one side of the fluid responsive member to the other to thereby control the position of the fluid responsive member. A second of these sources includes a valve which controls the supply of fluid under pressure to the fluid responsive member and the return of fluid from the fluid responsive member. The servo pump and valve are arranged in parallel with their flows being summed at the actuator.

Abstract: A control valve for a variable displacement pump or motor. The valve includes a pair of solenoids which are independently actuatable to port relatively high pressure fluid to their respective servo motor. A shuttle valve actuated by the high pressure fluid is used to simultaneously port the fluid from the other servo motor to a low pressure fluid source. A manual valving system is also provided having a pair of balls each biased into engagement with a seat to seal a passage to one of the servo motors. Movement of either ball off of its seat allows high pressure to flow to the respective servo motor. The high pressure fluid actuates the shuttle valve to port fluid from the other servo motor to the low pressure fluid source.

Abstract: A fluid system having a variable displacement fluid pump connected in a closed-loop fashion to a pair of inlet ports of a fluid motor of the type having two output shafts and a fluid pressure responsive means operable upon communication with fluid pressure through said inlet ports to translate said fluid pressure to one of the output shafts in the form of a high torque output while rotating one shaft at a low speed. The fluid pressure responsive means of the fluid motor is further operable to translate fluid pressure to the other of the drive shafts in the form of a low torque output while rotating the other shaft at a high speed. Suitable clutching means responsive to selective operation of the system are provided for alternate and independent coupling of the motor output shafts to a common system drive shaft to provide an output of which the speed and torque may be selectively varied from a high speed-low torque output to a high torque-low speed output.

Abstract: The cable drum for the hoist cable of a hoisting device is driven by a hydraulic motor with a constant displacement that in its turn obtains drive fluid from a pump with a variable displacement. The displacement of the pump, and with that the speed and rotational direction of the cable drum, is operated by means of the rod of a piston in a double acting hydraulic cylinder, the piston being displaceable in the cylinder by means of pressure fluid, which pressure and direction of flow is adjustable by means of valves, which in their turn are operated electrically from a control lever.

Abstract: An improved hydraulic drive system for a doubleacting hydraulic cylinder which drives or rocks the walking beam of an oil well pump. A closed circuit hydrostatic drive system is used to operate the double-acting hydraulic power cylinder unit and includes a variable displacement reversing swashplate pump driven at a predetermined constant speed by a prime mover such as an electric motor. Suitable automatic control means are provided for synchronizing the reversing movement of the swashplate with the rocking movement of the walking beam.

Abstract: A hydraulic control system includes a generating circuit for providing power to a work function. A driving apparatus operates the generating circuit. A control circuit is connected to the generating circuit and the driving apparatus for permitting delivery of power to the work function when the driving apparatus is operating up to a predetermined speed. The control circuit also stops delivery of power to the work function when the driving apparatus runs above the predetermined speed.

Abstract: A hydraulic control system includes a generating circuit for providing power to a work function. A driving apparatus operates the generating circuit. A control circuit is connected to the generating circuit and the driving apparatus for permitting delivery of power to the work function when the driving apparatus is operating up to a predetermined speed. The control circuit also stops delivery of power to the work function when the driving apparatus runs above the predetermined speed. The control circuit further includes a cut-off apparatus for stopping delivery of power to the work function when the driving apparatus is running up to the predetermined speed.