Abstract: A method of controlling the slewing of a revolving superstructure of a hydraulic backhoe includes setting a swing mode selector valve in a driving position to supply fluid discharged from a pump through a supply-and-discharge line to a hydraulic motor to drive the hydraulic motor for a driving operation, setting one of a pair of relief valves provided between the swing mode selector valve and the hydraulic motor, associated with the supply side of the hydraulic motor for a set relief pressure higher than the set relief pressure of a main relief valve for limiting the pressure in supply-and-discharge lines to the set relief pressure of the main relief valve while the hydraulic motor is operating in a driving mode, and setting the other relief valve associated with the discharge side of the hydraulic motor for a set relief pressure lower than the set relief pressure of the main relief valve to limit the pressure in the supply-and-discharge line associated with the discharge side of the hydraulic motor to the se

Abstract: A slewing control device for a crane for supplying a discharge oil from a pump through a direction selecting valve to a slewing motor and for controlling a rotational direction of the slewing motor. The device includes a selector provided in a main circuit between the pump and the direction selecting valve for selecting either an unload condition of the pump where a hydraulic oil in the main circuit is communicated with a tank or an on-load condition of the pump where the communication from the main circuit to the tank is blocked. A controller outputs a select signal to the selector to select the unload condition in response to detecting a dangerous operating condition. The controller also outputs a pressure control signal to an electromagnetic proportional pressure control valve provided between the direction selecting valve and a discharge port of the slewing motor to control oil pressure on a discharge side of the slewing motor when slewing needs to be stopped.

Abstract: In a hydrostatic transmission comprising a pump and a hydraulic motor arranged in a main line having low pressure and high pressure sections, wherein an oil drain line of the hydraulic motor is connected to the low pressure section of the main line, the housing of the hydraulic motor is freed from excessively high pressures in the main line by arranging a valve having an adjustable passage cross-section which decreases with increasing pressure in the main line before--in the direction of flow--the line connection of the oil drain line.

Abstract: A hydraulic control system includes a pump, a hydraulic cylinder and a cylinder hydraulic circuit interconnecting the pump and the cylinder. The circuit includes a first hydraulic fluid line extending between the pump and the cylinder and a control valve located in the fluid line for controlling the communication of fluid between the pump and the cylinder. A second hydraulic fluid line is in fluid communication with the first line downstream from the control valve. A first relief valve is located in the second fluid line and a first shut off valve is also located in the second fluid line and interposed between the first relief valve and the first fluid line. The shut off valve is solenoid actuated to a closed position. A motor hydraulic circuit includes a third hydraulic fluid line and a solenoid actuated motor control valve for controlling the flow of fluid through the third fluid line. An interconnect system is provided for operating the first shut off valve and the motor control valve in unison.

Abstract: By providing the work blade of a grader with a hydraulic regulation system where pressure limiting valves (14, 15, 16, 17) guide pressure reducing valves (10, 11, 12, 13) a constant pressure regulation of the work blade is achieved so that the work pressure set by the operator from his cab is maintained almost independent of the irregularities of the underlying surface.

Abstract: An automatic speed changing apparatus, employable for a motorcar, which includes a hydraulic pump on the driving side mounted on a driving shaft, a plurality of hydraulic motors on the driven side mounted on a driven shaft, a distributor including a cylinder and a piston slidably received in the cylinder, a hydraulic oil collecting pipe having a large diameter in which working hydraulic oil is stored for the hydraulic pump and motors on both the driving and driven sides, an idling lever pivotally supported in the cylinder to be operable during a period of idling and a piston lever for displacing the piston axially in the cylinder during normal operation and during a period of engine braking.

Abstract: A hydrostatic transmission having a housing with a sump and a pair of hydraulic displacement units interconnected by first and second fluid passages. A pair of bypass valves can be opened to place said first and second fluid passages in fluid communication. A recess, formed in the lower part of the housing, holds make-up oil and communicates with said first and second fluid passages when the bypass valves are opened. A passage extends upwardly from the housing recess and has its upper end normally sealed by seal means. A manually operable bypass rod extends lengthwise of the passage into the area of the housing recess and has structure associated therewith for causing opening of the bypass valves.

Abstract: A hydraulic drive system is equipped with an engine, a plurality of hydraulic pumps adapted to be driven by the engine and including a variable displacement hydraulic pump provided with a displacement varying mechanism, a hydraulic motor connected to the variable displacement pump, a hydraulic actuator for actuating the displacement varying mechanism of the variable displacement hydraulic pump, a working fluid feeding means for feeding the hydraulic actuator with a hydraulic fluid of a pressure according to the degree of control of an accelerator lever which is adapted to instruct a target revolution number of the engine, and a low-pressure circuit for allowing the hydraulic fluid to be discharged therethrough from the hydraulic actuator.

Abstract: An axle driving apparatus which houses in a transmission casing thereof a hydraulic motor and a hydraulic pump at a hydro-static-transmission and disposes in the transmission casing a center section for connecting the hydraulic motor and hydraulic pump, thereby fixing the center section at the butt joint of the casing and which disposes an oil filter and check valves or the like in the center section so that lubricating oil in the transmission casing is made absorbable as operating oil for the hydro-static-transmission.

Abstract: In a hydraulic circuit for a backhoe vehicle including a plurality of hydraulic pumps and operating valves for a pair of right and left vehicle-propelling devices and other work implements, two hydraulic circuits connected to the vehicle-propelling devices share a single unit of relief circuit adapted for selectively providing relief oil pressure in a plurality of steps. In a vehicle propelling operation or an excavating operation, the relief circuit provides a higher relief pressure to oil passages used in this operation than that provided for an all-pump-activated condition, hence, the engine output may be harnessed more efficiently.

Abstract: A hydraulic continuously variable speed transmission includes a hydraulic pump and a hydraulic motor, at least one of said hydraulic pump and motor being of variable displacement type. A hydraulic path is formed in a member of the pump which rotates in synchronism with an output shaft of engine, for communicating hydraulic a pressure chamber of the hydraulic pump with a drain. A check valve is provided in the hydraulic path for closing the hydraulic path under centrifugal force created by the rotation of the member when this member is in rotation faster than a predetermined speed, and for opening the hydraulic path against a centrifugal force when the member is in rotation slower than the predetermined speed.

Abstract: The vibrating roll apparatus has a hydrostatic roll body drive drive. An internal-combustion engine drives a pump unit which includes an inclined disk pump of variable displacement and a filling pump. At least one hydraulic drive motor which is fed a pressurized medium by the inclined disk pump powers the hydrostatic roll body drive. An eccentric body in the roll body of the vibrating roll is driven by a mechanical power transmission device with a built-in clutch also powered by the internal-combustion engine. According to the invention the clutch is flanged to the pump unit and provided with a hydrostatically-operated clutch mechanism, which is connectable with the pressurized side of the filling pump by a clutch valve for engagement of the clutch. In this way a space-saving compact form for the drive for the eccentric body including means for its control with optimum conditions for clutch operation is attained.

Abstract: An improved shifting device for the hydrostatic transmission of a lawn tractor or the like. The shifting device includes means for permitting a greater latitude of movement of the shift lever without effecting either forward or reverse movement. This is done by incorporating a linkage system for interconnecting the shift lever with the transmission control that includes a lost motion connection and by providing a leak path in the hydrostatic transmission so that a greater than normal pressure must be exerted before drive in one direction is possible.

Abstract: A control valve includes valve elements relatively displaceable in response to a predetermined variable (e.g., a steering torque) to define therebetween two parallel fluid flow paths connected between a fluid source and a fluid reservoir to produce pressure difference in a power cylinder. The control valve comprises a bypass path provided with a variable flow orifice that has an orifice area variable in response to said predetermined variable and an externally controlled variable flow orifice valve that has an orifice area variable in response to a second predetermined variable which is different from the first predetermined variable.

Abstract: A hydraulic continuously variable speed transmission comprises a hydraulic closed circuit for hydraulically connecting the hydraulic pump and the hydraulic motor, a direct clutch valve placed in the closed circuit to block it, a speed reduction ratio control actuator to control the speed reduction ratio, a direct clutch actuator for moving said direct clutch valve from a full-open position to a full-closed position, ratio detecting means which detects the speed reduction ratio and valve position detecting means which detects position of the direct clutch valve to find if the direct clutch valve is moved to a slight-open position. The direct clutch valve is moved quickly from the full-open position to the slight-open position when it is found by the ratio detecting means that the speed reduction ratio has become "1", and then the direct clutch valve is moved slowly from the slight-open position to the full-closed position when it is found that the direct clutch valve has been moved to the slight-open position.

Abstract: A bidirectional hydraulic servomotor system includes a variable-displacement motor which may impel or brake movement of a load member that either resists or assits movement by the servomotor, respectively. The direction of load movement is under control of a directional control valve with motor displacement and function (impelling or braking) being effected automatically to achieve controlled load movemement with minimal consumption of hydraulic fluid.

Abstract: An axle driving apparatus which laterally divides a transmission casing into two, a hydraulic pump vertically disposing a pump shaft and a hydraulic motor horizontally disposing a motor shaft are fixed in one transmission casing, the hydraulic pump and hydraulic motor are tight enclosed within the transmission casing in the state of joining both the transmission casing, an oil passage connecting the hydraulic pump and hydraulic motor is open at the bottom surface of the transmission casing, and an oil passage plate provided with connecting oil passages, a short-circuit valve, check valves and oil filter, is attached to the portion of the opening.

Abstract: An axle driving apparatus which houses within a casing thereof a hydraulic motor and a hydraulic pump constituting a hydro-static-transmission, provides in the wall of the lower half casing oil passages connecting the hydraulic motor and hydraulic pump, integrally forms a pump mounting surface at the horizontal wall at the lower half casing, and integrally forms a motor mounting surface at the vertical wall of the same, so that the oil passages in the vertical wall are turned vertically, thereby substituting for turning of the rotation direction by the conventional bevel gear.

Abstract: The invention is vehicle propulsion system having a pump driven by an engine, a hydraulic motor driven by the pump, and a ground engaging wheel driven by the hydraulic motor. On the drive shaft connected between the engine and the pump is a flywheel whose moment of inertia is varied by radially translating weights on the flywheel. Under normal vehicle operating conditions, the weights are translated outward, whereby rotational energy is stored in the flywheel. When more power is needed then the engine can provide, the weights on the flywheel translate inwardly so that the flywheel imparts rotational energy to the pump through the drive shaft. The propulsion system has means to maintain the engine in a narrow r.p.m. range where the engine is most efficient. Vehicle speed and direction is varied by controlling the flow speed and direction from the pump, which determines the speed and direction of the hydraulic motor.

Abstract: A variable assist power steering system comprises a control valve including valve elements relatively displaceable in response to a steering torque to define therebetween two parallel fluid flow paths connected between the fluid source (10) and the fluid reservoir to produce pressure difference in the power cylinder in response to the steering torque. The control valve includes a plurality of bypass paths, each arranged in parallel to one of plurality of serially arranged variable flow orifices forming the two flow paths and each provided with an externally controlled variable flow orifice valve which is operable responsive to a vehicle speed.

Abstract: A vehicle stabilizer apparatus having a plurality of hydraulic stabilizer actuators with each actuator having an integral isolation valve effective to enable operation of a sequentially operable device such as a boom cylinder only after ground-engaging feet associated with the actuators have been brought into firm contact with the ground or other supporting surface. Each actuator is mounted for bodily movement between upper and lower positions on an associated vehicle supported mounting pin. The actuator is caused to move to its upper position when the associated ground-engaging foot engages the ground and through a plunger and plunger spring associated with the isolation valve the position of the actuator is sensed. The isolation valve is in a hydraulic circuit to prevent operation of the boom cylinder unless the actuator is in its upper position.

Abstract: A grader has a grader blade which can be pressed against the ground or lifted off it by means of piston-cylinder drives. To be able to vary the downard pressure of the grader blade in its float position, either the piston chamber or the piston ring chamber of each drive can be charged with a working fluid under pressure when the grader blade is in the float position, so that the corresponding drive exerts a force on the grader blade which increases or decreases the downward pressure of the grader blade on the ground. While still allowing the grader blue to follow the contour of the ground.

Abstract: A hydraulically operated power transmission includes a hydraulic pump drivable by a power source, a hydraulic motor for driving a device, a primary oil passage leading from the hydraulic pump to the hydraulic motor, a secondary oil passage leading from the hydraulic motor to the hydraulic pump, a plurality of relief valves openable at higher and lower pressure levels, respectively, a shuttle valve for selectively connecting the relief valves to the primary and secondary oil passages in response to the difference between oil pressures in the primary and secondary oil passages, and a restriction disposed in an oil passageway extending from the primary oil passage through the shuttle valve to the relief valve openable at the lower pressure level, the restriction being located between the shuttle valve and the relief valve openable at the lower pressure level.

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

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

Abstract: A hydraulic drive system for one or more hydraulic motors, comprising a pump (1), a tank (25) for hydraulic fluid, one or more control valve sections (10, 11, 12) each being provided with a shunt passage and each being coupled to a respective hydraulic motor, a first shunt conduit (4) including the shunt passages of said control valve sections (10, 11, 12) connected in series for leading off of the tank (25) the temporarly surplus flow of hydraulic fluid from the pump (1), and a feed conduit (3) for connecting the control valve sections (10, 11, 12) in parallel to the pump (1).

Abstract: There is proposed a volumetric control device acting on a liquid, a gas or an emulsion and comprising a rotary body arranged within a housing having openings. The rotary body is axially displaceable. The regulation of the volume results on one hand from the rotation speed of the body respectively of that of the housing and on the other hand from the axial displacement of the rotary body. Within a given time, according to the rotation speed, a different quantity will be metered and according to the axial position a different opening volume is used for the metering.

Abstract: The present invention incorporates a free swing system into the hydraulic flow system of a boom crane in order to permit an operator to control the boom crane during the centering operation, which occurs immediately before and during the hoisting of a load. The free-swing system is incorporated into the hydraulic flow system between the swing control valve and the hydraulic swing motor and operates by "bleeding-off" a portion of the hydraulic fluid being pumped to or by the hydraulic swing motor so as to greatly reduce or control the rotational speed of the hydraulic swing motor.

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: A mechanical power regeneration system for a movable object comprising a sole variable displacement hydraulic pump being driven by the movable object, a first check valve connected between the output side of the pump and a first hydraulic line of a high pressure accumulator unit, a second hydraulic line of a low pressure accumulator unit, a second check valve connected between the second hydraulic line and the input side of the pump, a first controlled valve connected between the first hydraulic line and the input side of the pump and a second controlled valve connected between the second hydraulic line and the output side of the pump. When the movable object is to be slowed down by placing it in a braking mode, hydraulic fluid is transferred by the pump from the low pressure accumulator to the high pressure accumulator.

Abstract: A control system for terminating the power input to the picking units of a cotton harvester after a short delay by automatically causing a hydrostatic drive to return to neutral. A seat switch and a delay timer electrically connected to a solenoid valve on a servo control system of the hydrostatic pump deactivates the servo system and returns the pump swashplate to a neutral position to stop the unit movement when the operator leaves his seat. Another switch connected in parallel with the operator seat switch is activable when the unit drive is in neutral making the system effective only when the picking units are engaged. A service bypass circuit is provided which, when the hydrostatic lever is in a special low speed position and when the main ground drive of the transmission is in neutral, permits the units to be operated at a relatively slow speed by depressing a remotely located switch.

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 system comprised of a pump, a first valve in the inlet to the pump, and a second valve which activates or deactivates a third valve which permits the loading and unloading of the pump discharge. A motor is provided to operate the first valve for opening or closing the pump inlet. This motor also actuates the second valve in concert with the operation of the first valve to open or close a vent port to the third valve which opens or closes the passage from the pump discharge to tank, located away from the pump inlet. This permits unloading the pump discharge during the restriction of the pump inlet and allows the loading of the pump discharge after the opening of the pump inlet. With the pump inlet restricted, the system provides a low restrictive passage for circulating the prescribed small volume of flow used to lubricate and cool the pump.

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: A control system for operating positive displacement hydraulic motors to minimize pressure peaks and stresses associated therewith upon starting the motor at full fluid flow includes a self-closing pilot operated valve which, upon initiation of fluid flow to the motor bypasses a majority of the flow to a return line circuit and progressively closes to force pressure fluid to accelerate the motor to a preselected operating speed. The self-closing valve includes a spool type closure member which is pilot actuated through a timing orifice to commence closing upon initiation of fluid flow therethrough from the pump discharge or supply line. The closure member is spring biased in the open position and automatically resets itself to the open position upon shutdown of the motor operating valve.

Abstract: A hydraulic circuit system for use in hydraulically operated vehicles having a bidirectionally rotatable hydraulic motor with a brake unit, a directional control valve for controlling a pressurized fluid supply to the motor, bypass circuits connected between a fluid supply circuit and a drain circuit, a shadow valve provided in the bypass circuits, and an ON-OFF changeover valve provided in the bypass circuits for allowing the bypass circuits to connect with and disconnect from the shadow valve. The system further includes a cavitation preventing circuit device connected through check valves between the bypass circuits and the shadow valve so as to allow the bypass circuits to communicate with each other in co-operation with the shadow valve.

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: The present invention incorporates a free swing system into the hydraulic flow system of a boom crane in order to permit an operator to control the boom crane during the centering operation, which occurs immediately before and during the hoisting of a load. The free-swing system is incorporated into the hydraulic flow system between the swing control valve and the hydraulic swing motor and operates by "bleeding-off" a portion of the hydraulic fluid being pumped to or by the hydraulic swing motor so as to greatly reduce or control the rotational speed of the hydraulic swing motor.

Abstract: A constant speed hydraulic drive comprising a variable displacement hydraulic pump controlled to maintain a constant flow of hydraulic fluid even though a prime mover therefor is subject to speed variations. The constant flow rate delivered by the hydraulic pump is at a rate sufficient to drive a load hydraulic motor at a predetermined speed when the load hydraulic motor is subject to any given load. A pilot operated relief valve proportionally bleeds hydraulic fluid from ahead of the hydraulic motor in accordance with the speed and load of the hydraulic motor.

Abstract: A hydraulic circuit is disclosed for driving a bidirectional hydraulic motor from a pump via a hand operated directional control valve, as for propelling an earthmover or actuating an implement assembly thereon. For mitigating an abrupt pressure rise as when the motor is set into or out of rotation, the circuit has a pair of oppositely directed dual pressure relief valves connected in parallel with each other between a pair of main lines extending between motor and directional control valve. Each dual pressure relief valve is normally conditioned to pass at a predetermined lower pressure the pressurized fluid from one of the main lines and to pass at a predetermined higher pressure the pressurized fluid from the other main line.

Abstract: A synchronized mechanical-hydrostatic gearbox with infinitely variable drive ratio including a hydrostatic gear and a following mechanical gear coupled thereto. The hydrostatic gear includes a hydraulic transmission motor with variable displacement which is connected to the mechanical gear. The mechanical gear is made with at least two gear ratio stages and with means adapted for altering the displacement of the hydraulic transmission motor on alteration of the gear ratio of the mechanical gear to an extent corresponding to the gear ratio change. The gear box is intended to be incorporated in a transmission for vehicles, particularly terrain vehicles, preferably driven by an internal combustion engine.

Abstract: Hydraulic motors are conventionally employed in rotating the upper structure of excavators and the like. Protection from inertia induced hydraulic shock loads of some hydraulic control circuits involves the use of a separate bypass valve which continuously interconnects the motor conduits. The subject control circuit includes a pair of shunt valves each of which establishes restricted communication between the first and second motor conduits in a particular direction at their normal spring biased position. This allows limited free swing of the upper structure when the directional control valve is shifted from an operating position to the neutral position. However, shifting the directional control valve to an operating position causes the appropriate one of the shunt valves to shift to a blocking position so that no interconnection between the motor conduits exist.

Abstract: The transmission comprises a hollow input member (1) and a coaxial output member (2) supported for rotation relative to the input member. A positive displacement pump comprises a cylinder block (12) secured to the input member and a rotor (16) which is journalled on an eccentric pin (17) and which drives the pump pistons (15). A positive displacement motor comprises a stator part (6) secured to the input member and a rotor part (5) secured to the output member. The motor cylinders (8) are supplied with hydraulic liquid from the pump through duct means (35, 37, 39) in a disc-shaped control member (22) journalled on the eccentric pin (17) and rotating together with the pump rotor (16). Return flow from the motor to the pump occurs through a space (28) which within the input member surrounds the control member (22) and which communicates with each pump cylinder (14) during the suction stroke of the associated pump piston (15).

Abstract: A closed-center, non load-sensing controller (15) is disclosed for use with an unequal area steering cylinder (17). The controller includes valving comprising a spool (35) and sleeve (37). The sleeve includes an annular groove (65) in communication with the inlet port (29) and cylinder ports (73,75) in communication with the opposite ends of the steering cylinder. The sleeve defines an annular leakage groove (95) which is disposed to interrupt the flow of leakage fluid from the annular groove (65) to the cylinder ports (73,75), to eliminate undesired piston rod extension. When the valving is in neutral, leakage fluid collected in the annular groove (95) is communicated through radial bore (97), axial slots (83), and annular groove (81), axial slots (91), drain bore (99), drain bore (93), and then to the system reservoir.

Abstract: A continuously variable transmission (2) is constructed utilizing a constant displacement pump (4) of fixed fluid power stroke, rather than a variable displacement pump with a variable pump stroke. A fluid motor (14) is driven by the pump and has an output stroke. Means (22) are provided for varying the output stroke without varying the input power stroke.

Abstract: A speed control mechanism for a hydrostatically driven vehicle such as a street sweeper is disclosed which includes a selector lever. When the lever is in a variable engine speed position, depression of an accelerator pedal progressively opens the engine throttle from idle speed to high engine speed and progressively closes an inching valve thereby enabling the operator to comfortably drive the vehicle through stop and go traffic. When the lever is in a governor controlled high speed position, the engine throttle is opened and the engine is driven at high speed under control of the governor, and progressive depression of the throttle progressively closes the inching valve thereby providing optimum power while the vehicle is working, such as sweeping streets, with the speed of the vehicle being controlled by the position of the throttle and the position of the inching valve.

Abstract: An hydrostatic drive unit for driving a motor vehicle is provided including a pump, a hydraulic motor, connecting means between said pump and motor, a branch line connected to the connecting means, a shut-off means located in said connecting means, measuring means in said shut-off means for measuring the horizontal forces arising in the direction of the longitudinal axis of the vehicle, said shut-off means acting on the hydrostatic drive unit, said measuring means including a mass capable of being displaced in the direction of the longitudinal axis of the vehicle against a forcible stop, resilient means acting on said mass to position the same normally in a center position capable of movement in two directions on the longitudinal axis of the vehicle and in working connection with the shut-off element whereby during the exertion of force upon the forcible stop, said mass acts directly or indirectly on said shut-off element to control fluid flow in said connecting means.

Abstract: An apparatus for controlling sway and pendulous motion of suspended loads is disclosed which is particularly suited for embodiment in association with a mobile crane or similar hoist system. The arrangement includes stabilizing cables attached to a load lifting structure or spreader of the crane. The stabilizing cable is reeled and unreeled as the load lifting structure is moved up and down, respectively. The reel for the stabilizing cable is connected to a hydraulic motor which is driven by a pressurized fluid source when the load lifting structure is raised to reel in the stabilizing cable reducing and abating any pendulous motion. Upon unreeling of the stabilizing cable and lowering of the load lifting structure, the fluid flow through the hydraulic motor is reversed and directed through bypass circuitry around the hydraulic motor.

Abstract: A hydraulic brake valve system for use in a hydraulic circuit consisting of driving and braking fluid lines and including therein at least a hydraulic motor for the actuation of an inertia body such as, for example, a construction vehicle or work implements thereof has a counterbalance valve, a cross-over safety valve, a drain change-over valve and a timer valve. The cross-over safety valve consists of two common relief valves, each having two pressure receiving surfaces and adapted to relieve pressurized fluid acted on one of the pressure receiving surfaces at a low pressure and relieve pressurized fluid acted on the other pressure receiving surface at a high pressure, wherein the first port of one of said relief valves is connected with said driving fluid line and the second port thereof is connected with said braking fluid line, whilst the first port of the other relief valve is connected with said braking fluid line and the second port thereof is connected with said driving fluid line.

Abstract: A tractor hydraulic control system of the kind comprising a power lift with a hydraulic actuator (12) and a main control valve (17) controlling the supply of fluid from a pump (19) to the actuator, the system including selector valve means (50) interconnected with the main control valve (17) and movable between a first position in which flow to and from the actuator (12) occurs via the selector valve means under the control of the main control valve and the associated system control mechanism (28) and a second position in which the actuator is hydraulically locked in a given position and an external services outlet (51) is placed in communication with the pump. Linkage means (60,61,62) operatively connects the selector valve means (50) and the system control mechanism (28) to condition the main control valve (17) to cause the pump (19) to supply fluid to the external service outlet (51) via the selector valve means on movement of the selector valve means to the second position.