Abstract: A check valve system controls the flow of fluid between a spool valve and a hydraulic actuator and includes a pilot operated check valve that is controlled by a lock-out valve. The check valve has a poppet that engages and disengages a first valve seat in response to a pressure in a control chamber. The lock-out valve has an inlet connected to the control chamber, an outlet connected to an opening in the bore of the spool valve, and an second valve seat between the inlet and the outlet. A valve member that selectively engages and disengages the second valve seat and spool of the spool valve applies force to the valve member which responds by moving into engagement with the second valve seat. Thus in one position, the spool valve maintains the lock-out valve closed which traps pressure in the control chamber which tend to keep the check valve closed.

Abstract: An active suspension system isolates a first member from vibration in a second member. A hydraulic actuator is connected between the first and second members and includes a cylinder having a second chamber and a first chamber defined on opposite sides of a piston in the cylinder. A rod is attached to the piston with a first end extending out of the cylinder and a second end within the third chamber. A valve arrangement controlling flow of fluid between the first and second chambers and a source of pressurized hydraulic fluid and a tank which control applies force to the piston that counteracts the transmission of vibration between the first and second members. A load leveling valve assembly connects the third cylinder chamber selectively to the source or the tank to maintain the piston centered in the cylinder under static load conditions.

Abstract: A spool type control valve is operated by an electrically driven pilot valve. A pilot piston is attached to the control spool. As an electrical actuator moves the pilot spool, a greater pressure is applied to one side of the pilot piston than the other side, which causes movement of the control spool. When the control spool reaches the desired position, its positional relationship to the pilot valve defines a pressure differential across the pilot piston which exerts a net force on the control spool that counterbalances a spring force acting on the control spool. This defines an equilibrium position at which the control spool remains until subsequent motion of the pilot spool occurs which alters the pressure differential across the pilot piston.

Abstract: When different implements are attached to an agricultural tractor, various hydraulic actuators on the implement are operated by connection to the hydraulic system on the tractor. A single hydraulic fluid connector on the tractor has first and second ports with a separate valve assembly provided to control fluid of fluid to and from each port. This enables one doubling-acting hydraulic actuator to be connected to both connector ports so that the fluid flow to and from the actuator is controlled. For a different implement, one single-acting hydraulic actuator can be connected to one connector port and another single-acting hydraulic actuator can be connected to the other port of the same connector. Individual operation of the valve assembly for each port in this case allows independent control of the two single-acting hydraulic actuators.

Abstract: A spool valve section for a multiple valve assembly has a body with two opposing side surfaces. A plurality of mating surfaces are raised from each side surface. The mating surfaces surround the openings of fluid passages through the section and apertures for fasteners that secure the assembly together. The mating surfaces are spaced from a region of each side surface that is adjacent a bore in the body that receives a control spool. The fluid passages also are spaced from and do not intersect the spool bore. These characteristics of the spool valve section reduce distortion of the spool bore which could otherwise result from the pressure and fastening forces in the valve assembly.

Abstract: A suspension system has a pair of cylinders connected between the cab or axle and a chassis of a vehicle to isolate the driver from vibrations. A pair of hydraulic cylinders is coupled to opposite sides of the cab or axle and to the vehicle chassis. A separate accumulator is coupled each hydraulic cylinder to act as a hydraulic spring that attenuates side to side motion. A leveling valve selectively control the flow of fluid to or from both hydraulic cylinders to level the cab or seat in response to load changes.

Abstract: A screw having a driving socket capable of receiving a square socket (Robertson) type driver, a cross-recess (Phillips) type screw driver, and a flat blade driver.