Abstract: Fluid control circuits employed on construction vehicles to control the actuation of various work cylinders oftentimes include a system for sensing the fluid pressure in the cylinder and communicating such fluid pressure to a control device in signal form to closely control the displacement of a pump, the flow capacity of a pressure compensated flow control valve, or the like. The sensing system is normally associated with the spool of a directional control valve which must travel a substantial distance to effect extension or retraction of the cylinder and normally requires an "anti-rotation" device to insure proper alignment of the various ports and passages. Conventional high pressure systems of this type also pose potential leakage problems.

Abstract: A speed control and transmission vent valve (10) includes a first valve (12), a second valve (14) having first (64) and second inlets (66), an openable outlet (70) and a spool (62 or 62') movable in response to fluid in the inlets (64,66) between first, second and third positions, a passage (112) connecting the first valve (12) to the first inlet (64), and two-state switch means (16) for communicating fluid in the passage (112) to the second inlet (66) in response to one state of the switch means (16) to move the spool (62 or 62') from the first to the second position and for communicating fluid in the passage (112) to the first inlet (64) in response to a second state of the switch means (16) to move the spool (62 or 62') from the second position to the third position in which a fluid control signal is generated.

Abstract: PCT No. PCT/US 79/ 00573 Sec. 371 Date Aug. 6, 1979 Sec. 102(e) Date Aug. 6, 1979 PCT Filed Aug. 6, 1979Conventional directional control valves and the like normally include relatively complex and spatially separated centering and detent mechanisms for selectively maintaining a valve spool at centered and detent-held positions, respectively. Such valves are normally bulky and the casings therefor, primarily since they require machining, cannot be manufactured by die-casting methods. This invention overcomes the above problems by providing for the precise positioning of a valve spool (11) in its centered position by interassociating and engaging a centering mechanism (17) with a detent mechanism (30) by a stop (27), defined on a retainer (24) of the detent mechanism (30).

Abstract: PCT No. PCT/US79/00968 Sec. 371 Date Nov. 8, 1979 Sec. 102(e) Date Nov. 8, 1979, PCT Filed Nov. 8, 1979An improved load resolver (41) is provided of the type which receives a pair of generally unequal pressure signals (32, 34), and which resolves the pair of pressure signals (32, 34) by blocking the lesser and transmitting the greater. Each pressure signal (32, 34) is sent to the load resolver (41) by a respective control valve (18, 20) in a hydraulic system (10). Prior load resolver structures have required angled or intersecting holes therein or special porting therearound. The improved load resolver (41) comprises a first member (58) having a first, axially extending hole (64) and a second member (72) having second and third axially extending holes (78, 104). The members (58, 72) are fitted within a bore (48) of a control valve body (19).

Abstract: A control apparatus has a single control handle, first and second work elements, and first and second ramps each contacting a respective work element. Apparatus is further provided for selectively, progressively pivoting only one of the ramps in response to controllably moving the single control handle. One of the ramps pivotally moves in response to moving the handle in a first plane to a first position and in a different second plane from a first toward a second position. The other ramp pivotally moves in response to moving the handle in the first plane to a second position and in a different third plane from a first toward a second position. Respective work elements are thereby moved between a plurality of positions for controlling an operation such as the flow of fluid through associated, respective valves.

Abstract: An output shaft is rotatably mounted on a stationary support to selectively actuate a control valve of a hydrostatic transmission. A pair of levers are pivotally mounted on the output shaft in scissored relationship thereon and an actuating arm is rotatably mounted on the support to engage camming surfaces defined on first ends of the levers. A drive pin is secured to the output shaft to have opposite ends thereof engage bearing surfaces defined on second ends of the levers whereby swinging movements of the actuating arm in opposite directions will alternately transmit pivotal movements of the levers to the output shaft to control actuation of the control valve. The second ends of the levers are biased away from each other by a coil spring to normally engage the bearing surfaces with the drive pin.

Abstract: An underspeed actuator has a piston connected to a control means of a first pump driven by a prime mover and is movable between a first position at which the first pump is at minimum displacement and a second position at which the first pump is at maximum displacement. The underspeed actuator has first and second actuating chambers at opposite ends of the piston and a biasing device urging the piston towards the first position. The piston is movable between the first and second positions in response to pressure differential in said first and second chambers. A signal device controllably develops first and second control signals in response to the operating speed of the prime mover and delivers said first and second signals to respective first and second chambers. A first device controllably reduces the magnitude of fluid pressure in the first chamber in response to the rate of pressure rise of the output fluid of said first pump exceeding a preselected rate of pressure rise.

Abstract: The invention is concerned with an improvement in a pump having a pump body, a swash plate the rotational position of which controls the displacement of the pump and means mounting the swash plate for rotation about an axis generally centrally thereadjacent. The improvement serves to control the pump output. In a broad sense, the improvement comprises means internal of said pump body and acting between said pump body and said swash plate for biasing the swash plate towards a zero displacement position corresponding to a minimum displacement of the pump, and means responsive to discharge pressure of the pump reaching a first magnitude for overriding the biasing means and rotating the swash plate towards a full displacement position corresponding to a maximum displacement of the pump said overriding means comprising servo valve means within said pump body and pilot pump means acting to initially shift said servo valve means to allow discharge pressure to be applied in opposition to said biasing means.

Abstract: A fluid drive assembly has a pump, a variable displacement motor, a fluid circuit connecting the pump to the motor, and an actuator device for controlling the displacement of the motor. The actuator device is movable between a first position at which the displacement of the motor is at a preselected maximum and a second position at which the displacement of the motor is at a preselected minimum. A control system for the fluid drive assembly includes a source of fluid at a first preselected pressure value. A valve device is connected to the source of fluid and to the actuator device for controlling the fluid flow therebetween and is movable between a first position at which the source of fluid is in communication with the actuator device and a second position at which the source of fluid is blocked from communication with the actuator device.

Abstract: An underspeed actuator has a piston connected to a control means of a first pump driven by a prime mover and is movable between a first position at which the first pump is at minimum displacement and a second position at which the first pump is at maximum displacement. The underspeed actuator has first and second actuating chambers at opposite ends of the piston and a biasing device urging the piston toward the first position. The piston is movable between the first and second positions in response to pressure differential in said first and second chambers. A signal device controllably develops first and second control signals in response to the operating speed of the prime mover. First and second conduits deliver said first and second control signals to said first and second chambers, respectively. A shunt valve is connected to the first and second conduits for passing fluid expelled from the first chamber to the second chamber in response to said flow of fluid exceeding a preselected flow rate.

Abstract: The invention is concerned with an improvement in a load lifting apparatus which comprises a primary load member pivotally mounted about a generally horizontal axis on a frame, a tilt cylinder and a tilt piston movable relative to one another pivotally connected to the frame and the primary load member to provide impetus for pivotal movement therebetween, a secondary load member movable relative to the primary load member, a lift cylinder and a lift piston movable relative to one another connected to the primary load member and the secondary load member to provide impetus for linear relative movement therebetween, tilt cylinder valve means for controlling flow of pressurized fluid from pump means to the tilt cylinder and lift cylinder valve means for controlling flow of pressurized fluid from the pump means to the lift cylinder. The improvement of the invention provides protection which prevents the apparatus from overbalancing. The improvement operates by sensing a moment created by a load on the apparatus.

Abstract: A check valve comprises a housing having a ball normally disposed on a seat defined therein to prevent communication of fluid from an inlet to an outlet thereof. A torsion spring is mounted on the housing to have an end thereof engage the ball to hold it in its normally closed position and to permit opening thereof to communicate the inlet with the outlet when the level of fluid pressure in the inlet exceeds a predetermined level. In the preferred embodiment, the torsion spring is mounted on a rotary member rotatably mounted in the housing to selectively adjust the closing force applied to the ball to vary the pressure setting thereof. During assembly of the valve, a pin is secured to the housing in blocking relationship across an outlet passage to limit pivotal movement of the end of the spring and to prevent the ball from rolling therepast.

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 control for selectively controlling operation of left and right side drives for providing a selective steering drive of a vehicle. The control includes a single manually operable control lever and mounting structure for transmitting selective movement of the control lever through suitable push-pull linkages to the vehicle drives. The control is arranged to effect a change in the gain of output lever portions thereof in effecting the desired controlled steering operation of the drives. The change in gain is controlled by the engagement of rollers associated with the control lever against output levers associated one each with the push-pull linkages and left and right side vehicle drives.

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 fluid drive arrangement of a vehicle is shiftable to forward and reverse drive conditions when actuating fluid from an auxiliary source of pressurized fluid is directed to a hydraulic actuator device of the fluid drive arrangement and is shifted to a neutral position automatically when the flow of actuating fluid to the hydraulic actuator device is blocked. A solenoid operated valve device is disposed between the auxiliary source of fluid and the hydraulic actuator device and has an energized fluid supplying position for directing actuating fluid to the hydraulic actuator device and a de-energized fluid blocking position for blocking pressurized fluid from the hydraulic actuator device. An electrical switch is disposed within a conductor line connecting a source of electrical energy to the solenoid operated valve device and has a closed position for completing an electrical circuit to energize the solenoid operated valve device and an open position for de-energizing the solenoid operated valve device.

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 control linkage for a servo valve of a variable displacement hydraulic machine includes a lever arm adjustably connected to the servo valve by means that is operative to adjust the null position of the valve with respect to the lever, and includes cam means for adjusting the length of the lever arm.

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 together with a venturi manifold which function together 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 engine or prime mover speed as determined by load conditions, an underspeed actuator valve unit includes a piston which is hydraulically responsive to the differential pressure in order to adjust the effective moment arm for a lever which controls displacement of the pump unit.

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