Abstract: Left and right two stage brake valves communicate fluid pressure to left and right brake mechanisms, each brake valve having an inlet for receiving pressurized brake fluid, a reservoir, a stepped bore and a stepped piston. The stepped bore and the stepped piston forming a high volume prefill chamber and a high pressure chamber. A prefill drain valve communicates the prefill chambers to the reservoir only when pump pressure is available at the inlet and blocks communication between the left and right prefill chambers and between the prefill chambers and a reservoir when pump pressure is not available at the inlet.

Abstract: A hydraulic system includes a hydraulic pump which provides pressurized fluid at an output port as a function of pressure in a load sensing port, a hydraulic reservoir, and a load pressure sensing line connected to the load sensing port. A solenoid operated implement control valve controls fluid communication to and from a hydraulic function such as a cylinder. A supply control valve has a first position wherein the reservoir is communicated with the load sensing port and a second position wherein the pump output port is communicated with the load sensing port. A spring urges the valve member to its first position, and a solenoid is energizable to move the valve member to its second position. The solenoid is energized when the implement control valve is activated so that the supply control valve communicates pump pressure to the load sensing port and the pump will operate at full capacity whenever the second hydraulic function is operated.

Abstract: A female coupler can operate in both a push-pull and a lever-actuated connect/disconnect fashion. Double lock ball controlling ramp surfaces are provided around the receiving bore of the coupler to allow the lock balls of the coupler to withdraw from the receiving bore when the receptacle is moved either into or out of the housing. The coupler can be moved into or out of the housing by pushing the male coupler into or pulling it out of the female coupler, or by use of a lever-actuated cam. A piston-type flow-check valve is provided to open the male check ball and hold it open despite transient surges. This flow-check valve is hydraulically actuated. A bleed valve for the hydraulically actuated flow-check valve is activated to release the flow-check valve when the lever is actuated or when the receptacle is pushed into the housing, thereby reducing the force needed for coupling.

Abstract: A hydraulic motor has its lube drain connected to the motor return line. A motor seal protector valve has a pilot which responds to pressure in the motor return line. Normally, the valve connects system pressure to the motor inlet. High pressure in the return line causes the pilot to move the valve to block the motor feed line and then to connect the motor feed line to sump. In a preferred embodiment, system pressure is connected to the plot to "lock up" the valve in response to return line overpressurization.

Abstract: A combine includes a variable displacement, reversible delivery pump which drives main drive wheels via a main hydraulic drive unit and which drives a pair of steerable wheels via auxiliary hydraulic drive units. A pair of pressure-limiting and relieving valves are connected between the auxiliary drive units and the pump so that auxiliary drive units with lower pressure ratings than that of the main drive units can be used. The valves relieve pressure from the auxiliary drive units during dynamic braking.

Abstract: A weight-balancing system for a farm implement, such as a disk harrow with foldable wings operated by wingfold cylinders, includes a selective control valve for controlling fluid communication to the head and rod ends of the wingfold cylinders. A pair of pressure-reducing/relieving valves permit individual adjustment of the pressures in both the head and rod ends to achieve the desired balance. In a preferred embodiment, a pilot-operated, two-position valve is connected between the rod ends and one of the pressure-responsive valves. The two-position valve is operated by pressure signals generated by a flow-responsive switching valve connected between the two-position valve and the selective control valve. The switching valve and the two-position valve cooperate to block the pressure-controlled outlet of the one pressure-responsive valve and the rod ends and to bypass return fluid flow from the rod ends to sump when the cylinders are being extended.