Abstract: This disclosure provides for pressure limiting a hydraulic system to a desired pressure value by a particular circuit by controlling and closing the compensator when the desired pressure setting is achieved. Closing the compensator will reduced the pressure head and flow in the circuit resulting in improved efficiency. One illustrated embodiment of the disclosure provides a relief valve in the pilot signal for a compensator. The method relates to limiting the pressure on an open side of the compensator, such that the pressure on the other side closes the compensator thereby limiting the pressure and also flow in the hydraulic circuit. In other words, the pressure on the open side is limited by the relief valve. Thus, the pressure on the other side increases thereby regulating the flow and pressure through the compensator.

Abstract: A method to recover energy in a reversible hydraulic motor system during a motor reverse event is disclosed. A swashplate of a hydraulic motor is pivoted over a center position when the hydraulic motor rotates in a first direction and is due to receiving a pressurized fluid from a pump. Thereafter, by de-stroking the pump a pressurized fluid to the hydraulic motor is restricted. Then, a valve is moved to a charge position to store the pressurized fluid into an accumulator. Next, the stored pressurized fluid of the accumulator is discharged to the hydraulic motor as the hydraulic motor begins rotation in an opposite, second direction. Subsequently, the valve is moved to a block position to inhibit flow of the pressurized fluid into or out of the accumulator. By up-stroking the pump, a continuous rotation of the hydraulic motor in the opposite, second direction is maintained.

Abstract: This disclosure provides for pressure limiting a hydraulic system to a desired pressure value by a particular circuit by controlling and closing the compensator when the desired pressure setting is achieved. Closing the compensator will reduced the pressure head and flow in the circuit resulting in improved efficiency. One illustrated embodiment of the disclosure provides a relief valve in the pilot signal for a compensator. The method relates to limiting the pressure on an open side of the compensator, such that the pressure on the other side closes the compensator thereby limiting the pressure and also flow in the hydraulic circuit. In other words, the pressure on the open side is limited by the relief valve. Thus, the pressure on the other side increases thereby regulating the flow and pressure through the compensator.

Abstract: A fan drive is disclosed which includes a planetary gear set having a first rotatable output member connected in driving relation to the fan, a second rotatable output member connected in driving communication with a hydraulic circuit, and a rotatable input member connected in driven communication with a power source, the first and second output members being connected in differentially rotatable communication with the input member. During operation, the hydraulic circuit is operable to vary the rotational speed of the second rotatable output member of the planetary gear set, to thereby vary the rotational speed of the first rotatable output member and the connected fan. According to one preferred aspect of the present invention, the input member of the hydraulic circuit is an input shaft of a hydraulic pump, the rotational speed of the pump being variable by throttling fluid flow therethrough.

Abstract: The present quick drop valve control provides both quick drop and float functions by moving a quick drop valve to a position interconnecting the drop and lift sides of a pair of lift cylinders when a directional control valve reaches a predefined position. The quick drop function valve is established by simultaneously energizing a first solenoid valve to communicate a shift end of the quick drop valve with a resolved pressure port of a resolver connected to the drop and lift sides and a first solenoid of a second solenoid valve to communicate a spring end of the quick drop valve with the drop sides so that the quick drop valve moves to the interconnecting position combining fluid expelled from the lift sides with fluid going to the drop side from a pump.

Abstract: A check valve normally blocks fluid flow from a bore to a passage and includes a spring normally holding a ball in sealing engagement with a valve seat to form a primary metal-to-metal hard seal. Another spring normally holds a poppet in engagement with another valve seat causing an annular protuberance formed on the poppet to sealingly engage a resilient seal to provide a more positive secondary soft seat seal. The poppet is unseated from the valve seat by a stem of a piston prior to the ball being unseated from the valve seat by a guide stem of the poppet so that the soft seal is opened at essentially zero flow conditions.

Abstract: A blade control system includes a directional control valve, a fluid regeneration valve and a selector valve for selectively controlling fluid flow between a pump and first and second hydraulic cylinders and between the cylinders. With the valves positioned at preselected operative positions, pressurized fluid from the pump is directed to the head end chamber of the first cylinder, fluid expelled from the rod end chamber of the first cylinder is diverted to the head end chamber of the second cylinder, and fluid expelled from the rod end chamber of the second cylinder is combined with the fluid being directed to the head end chamber of the first cylinders to provide two stages of fluid regeneration for increasing the extension speed of the cylinder.