Abstract: An example valve includes: a first port, a second port, and a load-sense port; a valve piston configured to block fluid flow from the first port to the second port when the valve piston is in a neutral position; a reverse flow spring applying a first biasing force on the valve piston in a proximal direction; and a pressure compensation spring disposed in a spring chamber and applying a second biasing force on the valve piston in a distal direction, wherein when pressure level of fluid at the second port is higher than pressure level of fluid at the load-sense port, fluid flows from the second port to the spring chamber and the load-sense port, and wherein when pressure level of fluid at the load-sense port is higher than pressure level of fluid at the second port, fluid of the load-sense port is provided to the spring chamber.

Abstract: A method for operating a hydraulic system has at least one supply device, in particular a hydraulic pump (3) supplying different hydraulic consumers. A synchronizing device (33, 35) ensures that, if at least one hydraulic consumer is not supplied sufficiently, the deficit in volumetric flow for that consumer is compensated such that all the consumers compensate for the deficit equally.

Abstract: A load balance is adjusted to be appropriate even if shared loads of lifting jacks are fluctuated from an initial setting state caused by cumulative errors of suspending rods. It is a load balance adjusting method of the lifting jack when a lifting module is jacked up by the plural lifting jacks via the suspending rods. The shared loads of the lifting jacks jacking up the respective suspending rods coupled to the lifting module are detected. A height of the lifting jack is adjusted when a fluctuation relative to a setting shared load stored in advance exceeds a prescribed range, to thereby adjust to be the setting shared load.

Abstract: A circuit arrangement includes a load sensing system (LS) with individual loads (10,14) arranged in series forming a series section, and in parallel forming a parallel section. A hydraulic supply circuit (12) includes a supply pump (P) and a runback (16) for fluid. The load sensing system (LS) determines the highest load pressure in the series section and the parallel section. The loads of the parallel section can be actuated independently from the pressure level of the loads of the series section due to the highest load pressure being transferred as a control pressure to a valve unit (18) such that, as long as the load pressure of the parallel section is higher than the load pressure of the series section, the valve unit restricts the runback (16) so that the pressure of the supply pump (P) matches or exceeds the pressure required in the parallel section. Sufficient fluid pressure for the load in the parallel section is ensured independently of the number of loads in the series section.

Abstract: An actuator for opening a poppet exhaust valve, which is closed by a spring and opens in normal operation against a relatively low pressure and which opens for compression braking against a relatively high pressure, is motivated in either event by the same hydraulic pressure. The actuator has a unitary central valve and piston element, which is coaxially directed toward the exhaust valve stem and has an area providing, when subjected to the pressure, a force sufficient to open the exhaust valve for normal operation but insufficient to open the exhaust valve during compression braking. The element extends through a relatively larger diameter annular piston which is slidably fitted about the element and within a bore receiving the annular piston. In normal operation, the element provides enough force to move from an unactuated position and open the exhaust valve, and initial movement of the element closes off passages in the element that admit the pressure to the piston which thus does not move.

Abstract: In a hydraulic apparatus for traveling, a left direction switching valve is formed by forming a spool bore having a pump port, an actuator port and a return port in a first valve block, and by disposing a spool within the spool bore for establishing and blocking communication of respective of the ports to another of the ports, a right direction switching valve is formed by forming a spool bore having a pump port, an actuator port and a return port in a second valve block, and by disposing a spool within the spool bore for establishing and blocking communication of respective of the ports to another of the ports, and a switching valve is formed by forming a spool bore having a primary port and a drain port in a third valve block, and by disposing a spool within the spool bore for establishing and blocking communication between respective of the ports and another of the ports.

Abstract: A control system for a press having a clutch and a brake includes a clutch control valve and a brake control valve. The clutch control valve operates the clutch by supplying pressurized air to the clutch. The brake control valve operates the brake by supplying pressurized hydraulic fluid to the brake. The brake control valve is activated by pressurized fluid from the clutch control valve in order to insure simultaneous release of the brake with engagement of the clutch as well as simultaneous application of the brake with disengagement of the clutch.

Abstract: A direction control valve is formed by providing a main spool for establishing and blocking communication between an inlet port, first and second actuator ports and first and second tank ports. A pressure compensation valve comprising a check valve portion and pressure reduction portion is provided for compensating the pressurized fluid with a load pressure and supplying it to the inlet port. A plurality of valve blocks are connected to each other with respective first and second tank ports and respective pump ports in fluid communication. A pump port of one of the valve blocks is connected to a main inlet port, and a tank port of one of the valve blocks is connected to a main tank port. Thus, a hydraulic circuit for distributing a pressurized fluid from a single hydraulic pump to a plurality of actuators is provided.

Abstract: The invention is directed to a foldable agricultural implement frame having an extended working configuration and a folded transport configuration. The frame comprises a center section and two wing section. Each of the wing sections have row markers that are extended and retracted by a row marker hydraulic circuit. The row marker hydraulic circuit is provided with first and second supply/return lines each having a two-position latching valve. A mechanical linkage comprising a rod extends between the center section and one of the wing sections, for shifting the latching valves to their checked position, when the implement frame is folded from its working configuration to its transport configuration. The latching valves lock the row markers in their retracted transport position.

Abstract: To excavate sticky soil such as clayey soil, left and right buckets of a clamshell bucket are slightly inclined, thereby reducing the force to pull the buckets from a hole. The clamshell bucket includes left and right buckets which are closable, thereby holding soil, and a hydraulic cylinder having a stroke reserve so as to be further extendible after the buckets are closed, whereby the closed buckets can be displaced sidewardly relative to the vertical.

Abstract: Material such as trash or refuse is packed in a container by opposed hydraulic packing and ejecting cylinders. Each cylinder is controlled by a hydraulic control valve with the control valve controlling the ejecting cylinder being, in effect, operated by the control valve for the packing cylinder. This is accomplished by sensing the pressure applied to the packing cylinder and when the pressure reaches a predetermined level, a pilot dump valve, in the ejecting cylinder is opened to allow the piston in the ejecting cylinder to retreat. When the pilot pressure drops below the predetermined level, the pilot dump valve closes, allowing the packing cylinder to exert additional packing force. In this way the piston in the ejecting cylinder inches back and the material is intermittently packed. An anti-cavitation check is provided so as to fill the chamber of the ejecting cylinder as the piston retracts.

Abstract: A hydraulic control valve apparatus including a flow control valve having a pair of variable throttles, a feeder passage, a pair of load passages, directional control valve devices comprise a seat valve having a seat valve body movably disposed in a housing to form an auxiliary variable throttle in the feeder passage, and a control variable throttle (33) formed in the seat valve body for changing an opening area in accordance with an amount of movement of the seat valve body; (b) a pilot line (24, 29-31, 35-37) for communicating a portion (7C) of the feeder passage upstream of the auxiliary variable throttle with a downstream portion (7A, 7B) of the feeder passage through the control variable throttle to determine the amount of movement of the seat valve body in accordance with a flow rate of the hydraulic fluid passing through the pilot line; and (c) pilot flow control (400; 401; 403; 405; 406; 407; 408) having a pilot variable throttle (45) disposed in the pilot line and input (800; 52-59; 159, 54-59; 231A,

Abstract: Hydraulic actuators are fed by a single flow-rate generator, each being connected to it through a proportional directional valve, the unit including a device for detecting the highest of the pressures prevailing upstream of the throttle provided by a controlled spool in the respective proportional directional valves, and, in each of these an actuation device to cause the compensating spool to respond to the highest of the upstream pressures thus detected.

Abstract: The present invention includes a method for improving operating efficiency of a hydraulic actuator loop and an improved hydraulic actuator loop. The method includes transferring hydraulic fluid between a first and a second hydraulic actuator when the actuators are disengaged from a load and transferring hydraulic fluid from an energy source to each of the actuators separately when the actuators engage the load. The method also includes transferring fluid from the energy source to the first actuator when the actuators are approaching the load and transferring fluid from the first actuator to a drain when the actuators are retracting from the load.

Abstract: A pilot-actuated, pressure-compensated flow and directional control valve assembly (11) is provided in which a main valve spool (95) is positioned in response to a pressure differential between a pilot chamber (119) and a reaction chamber (117). Flow of fluid from an inlet port (29) is controlled by means of a pilot valve assembly (97), into the pilot chamber (119), while fluid flows out of the pilot chamber (119) through a fixed orifice (67) to a pump load sense port (61). The main valve spool (95) acts as an inlet compensator. If the pressure at a load L is above inlet pressure, the main valve spool (95) acts as an inlet check, preventing reverse flow. If there is a higher load pressure at another load circuit in the system, such as a steering valve S, there will be an increase in pressure in the reaction chamber (117), thus closing off the main spool (95), reducing the flow from the inlet port (29) to the work port (47), and giving more priority to the steering valve S.

Abstract: There is disclosed a solenoid-operated selector valve adapted for control of hydraulic clutches such as of a tractor. The selector valve has four ports and can assume two positions. The selector valve includes a spool having an axially extending hole. A piston and a sequence valve are held in this hole. The sequence valve can relieve the pressure. The hole is in communication with the outside of the spool via first through third radially extending holes. The pressure inside one cylinder port which is normally connected with the pump port is maintained constant even when the engaged clutch is being switched to the other. This pressure is not reduced down to zero until the pressure inside the other cylinder port reaches a predetermined pressure.

Abstract: A change-over valve including a valve housing defining an inlet port for receiving fluid from a fluid pressure supply, a first outlet port for feeding operating fluid to a first fluid responsive actuator, a second outlet port for feeding operating fluid to a second fluid responsive actuator, and drain port means for draining fluid to a fluid reservoir; and a spool retained by the housing and movable therein between first and second positions, the housing and the spool in its first position providing communication between the inlet port and the first outlet port and preventing communication between the inlet port and the second outlet port, and the housing and the spool in its second position providing communication between the inlet port and the second outlet port, and preventing communication between the inlet port and the first outlet port.

Abstract: An automatic pressure control device built in a hydraulic actuator driving circuit for driving a plurality of actuators of a construction machine or the like by a single hydraulic pump through respective pilot changeover valves is provided for automatically shuttling the changeover valve of each actuator to reduce its demanded flow rate and uniformly control the operation speeds of all actuators. To this end, the device is arranged to drain an excessive flow rate of the hydraulic pump through a series connection of a flow rate control valve controlled by the highest load pressure of the actuators and a resistance passage including a shuttle and to control the pilot pressure of each pilot changeover valve in response to a pressure at the junction of the series connection.

Abstract: In the neutral position of a directional control valve in which the connection of the constant pump to the consumer is interrupted the entire delivery of the constant pump is led via a bypass valve to the tank. According to the invention the regulating range of the bypass valve is increased by an additional connection which is controlled by a further piston which in the neutral position of the directional control valve is displaced by a weak spring into the open position and thus ensures a pressureless circulation of the pump working medium to the tank.

Abstract: Power fluid from a pump are provided through one power fluid branch conduit to an extend port for activating the smallest cylinder of a multi-stage packing cylinder and fluid is conducted through a second extend branch conduit to a second port which provides fluids to the larger cylinders of the packing cylinder. A normally closed sequence value is in the second branch conduit. When the pump first is activated, fluid goes through the first extend branch conduit to extend the smallest stage of the packing cylinder. When the smallest stage is fully extended or reaches resistance, the pressure in the pump output conduit rises. When this pressure reaches a preselected value, the sequence valve is opened and high pressure fluid is directed through the second branch conduit and second port to provide power fluid to the larger cylinders of the packing cylinder.

Abstract: An electronic bucket positioning and control system for a vehicle of the type including a hydraulically controlled boom assembly and bucket. The bucket positioning and control system can operate in a bucket positioning mode, bucket return to position mode, bucket anti-rollback mode, and tilt cushion mode.

Abstract: A self-regulating hydraulic control circuit for controlling the flow of fluid to and from the cylinder of a double-acting hydraulic motor employs two pumps, one of which supplies fluid at a relatively high pressure and low displacement while the second pump is a relatively high displacement pump which operates only against a relatively low pressure requirement. The system is especially adapted for applications where, during a working stroke, the piston of the hydraulic motor moves from a start position through a first portion of the stroke during which the piston encounters but a minimal resistance to movement and then suddenly encounters a high resistance to movement. One example of such an application would be a press in which, at some point during the stroke of the piston, a tool carried by the piston initially encountered a workpiece.

Abstract: In a sensitive analytical instrument having an optical bench carried by a base member, new and improved vibration and shock isolation apparatus which includes three spaced pneumatic mounts interposed between the optical bench and the base member to provide vibration and shock isolation therebetween, each of the mounts having a preselected optimum linear range of operation, a source of pressurized gas, apparatus for individually controlling the inflation and deflation of each of the mounts with pressurized gas to maintain actual operation of each of the mounts within its preselected optimum linear operating range.

Abstract: A hydraulic circuit for a self-undecking crane having retractable legs with extendable jacks for elevating and supporting the crane upper. Hydraulic cylinders move the legs between a retracted position and an extended position in which the jacks are engageable with the ground and isolation valve devices in the hydraulic circuit prevent retraction of said legs when the crane upper is supported on the extendable jacks.

Abstract: In a high pressure hydraulic system a slave unit is supplied with fluid from a source through a control valve assembly. The assembly has a valve mechanism to control flow between ports communicating with the source and slave unit. The valve mechanism has two members, a first member controlling flow through the first port in response to a spring, a solenoid, and the pressure differential, the solenoid being unable to move the member against a significant pressure differential, and a second member controlling flow through the second port in dependence on the first member, the pressure differential and a spring. The first port has an elastomeric seal preventing leakage when the port is closed. The system has particular advantages when it is used as a vehicle suspension levelling system, in which an electronic control system controls the supply of fluid from an accumulator through a manifold and control valve assemblies to hydraulic suspension struts in accordance with ride height signals.

Abstract: A seed cotton transport is provided to transport seed cotton from the cotton stripper or harvester to a module builder. The basket upon the trailer or transport is pivoted about a point which is elevated above the sides of the module builder which is approximately eleven feet above the surface of the ground. The pivot is outboard of the wheels of the trailer. In the dump position, the weight is primarily to one side and as indicated above is very high. To prevent the trailer from overturning, stabilizing struts are hydraulicly extended any time the tilt or dump cylinders are pressurized to elevate the basket. A restricted one-way valve is used to insure that the cylinders operate in proper sequence.

Abstract: An excavator including a boom pivotally moved by boom cylinders, an arm pivotally moved by an arm cylinder and a bucket pivotally moved by bucket cylinders further includes a boom detecting device detecting a pivotal displacement of the boom and producing a first pilot pressure substantially proportional to the pivotal displacement of the boom and a bucket detecting device detecting a pivotal displacement of the bucket and producing a second pilot pressure substantially proportional to the pivotal displacement of the bucket. The first pilot pressure is supplied via a first conduit to a first valve switching pilot pressure port of a control valve device, and the second pilot pressure is supplied via a second conduit to a second valve switching pilot pressure port of the control valve device. The control valve device is connected to the bucket cylinders in such a manner that a piston side of the bucket cylinders can be drained.

Abstract: Apparatus and method for cutting and feeding foliage material from a stack, the apparatus comprising a wheeled vehicle, for example a wagon pulled by a tractor, capable of being displaced along the ground, a tiltable bed thereon disposed in a parallel position between ground engaging wheels and a powered conveyor so that a stack of foliage may be loaded onto the bed from a position on the ground (or unloaded from the bed back to the ground) and also may be successively advanced along the conveyor bed to provide an overhang beneath and forward of a rotating angularly disposed variable cutter which travels horizontally and then vertically downward in a zig-zag pattern to successively cut slices of foliage from the overhang of the stack.

Abstract: A hydraulic synchronous driving mechanism provided with at least two piston-cylinder assemblies, each having a bottom chamber and a ring chamber and the piston rods of which engage a counterdevice adapted to synchronously load piston rods mutually in opposite directions, a hydraulic fluid circuit provided with at least a pump and a reservoir, whereby there are pair-wise arranged volumetric pump-motors in fluid lines throughconnected to the bottom chamber of the one cylinder and the ring chamber of the other cylinder, which pump-motors are mutually coupled for a constant supply ratio, while the fluid line sections extending from the pump-motors to the cylinders are throughconnected to only one cylinder chamber.

Abstract: A selectively rotatable load clamp for lift trucks, having a pair of openable and closable clamp arms. The clamp arms are capable of shifting the position of a load relative to the lift truck by movement of the clamp arms in unison, by which the load may be moved relative to the lift truck between a position of equal extension, wherein the forward ends of the clamp arms extend a substantially equal distance forwardly of the lift truck, and a position of unequal extension wherein the forward end of one clamp arm extends a greater distance forwardly than the forward end of the other clamp arm. The fluid motor apparatus for accomplishing such shifting function is selectively actuatable only in certain predetermined rotation positions of the clamp, that is, those positions where the two clamp arms are disposed at substantially a 45.degree. angle relative to horizontal.

Abstract: A controlling apparatus for bulldozer blade in which the control is carried out automatically or manually.The apparatus comprises an electromagnetic valve for controlling a cylinder of the bulldozer blade, a switch for changing the control of the bulldozer blade automatically or manually, a safety relay connected with said switch, the safety relay being adapted to be actuated only when the switch is maintained in a manual operating position, and a load reading relay adapted to be actuated by a signal fed from a load detecting circuit for supplying a signal to one of the solenoids of the electromagnetic valve.

Abstract: A work vehicle with a fluid pressure circuit system comprising an actuator pump, a work equipment mounted on the vehicle and adapted to swivel on a vertical axis, a fluid pressure circuit connected to the actuator pump to actuate the work equipment, and a drive for swivelling the whole of the work equipment. A fluid pressure circuit portion of the fluid pressure circuit is connected to the actuator pump and to the drive to actuate the drive and a control valve is provided on the fluid pressure circuit for actuating the drive. A by-pass route is connected to a supply route and a discharge route of the circuit, at a portion of the fluid pressure circuit between the control valve and the drive. The arrangement is adapted to permit part of the fluid supplied by the actuator pump to short-circuit by way of the by-pass route and smooth the operation of the work equipment.