Abstract: A method of controlling a float function of a cylinder 25 having a first side and a second side includes connecting the second side of the cylinder to a reservoir 15; connecting the first side of the cylinder to an output of a pump 20 and to the reservoir; and supplying an amount of flow from a pump less than an amount supplied by the pump under loaded conditions. A three-position directional control valve 30 having a pump port, a reservoir port, a first cylinder port, and a second cylinder port may be provided to effectuate aspects of this method.

Abstract: A cushioned swing circuit provides the reduction of oscillation common in the operation of heavy equipment such as with boom members. The circuit utilizes a transfer of high pressure fluid flow (caused by the inertial of the swing during rapid deceleration) from one leg of the circuit to the other leg of the circuit or to the sump which serves as decompression for the oil that would ordinarily be trapped in the leg. These phenomena create the swing cushioning effect.

Abstract: A method of controlling a float function of a cylinder 25 having a first side and a second side includes connecting the second side of the cylinder to a reservoir 15; connecting the first side of the cylinder to an output of a pump 20 and to the reservoir; and supplying an amount of flow from a pump less than an amount supplied by the pump under loaded conditions. A three-position directional control valve 30 having a pump port, a reservoir port, a first cylinder port, and a second cylinder port may be provided to effectuate aspects of this method.

Abstract: A cushioned swing circuit provides the reduction of oscillation common in the operation of heavy equipment such as with boom members. The circuit utilizes a transfer of high pressure fluid flow (caused by the inertial of the swing during rapid deceleration) from one leg of the circuit to the other leg of the circuit or to the sump which serves as decompression for the oil that would ordinarily be trapped in the leg. These phenomena create the swing cushioning effect.

Abstract: Electro-hydraulic systems (10, 110, 210, 310, 410, 510, 610 and 710) control multiple hydraulic motors without objectionable erratic or jerky motion. The system (10) includes a variable displacement pump (20), an electronic controller (30), a direction control valve (40), first and second pump outlet valves (60) and (70), and a fluid reservoir (80). The pump (20) does not require or use a load feedback signal to control pump output. The controller (30) provides electric control signals to a pump control (21) and to individual hydraulic motors (51). A load sense circuit (46) resolves a highest load sense pressure Ps, which is communicated to the first and second pump outlet valves (60) and (70). The first pump outlet valve (60) limits the maximum load sense pressure. The second pump outlet valve (70) limits the maximum pressure differential between the pump outlet and the load sense pressure.

Abstract: A hydraulic system (10) includes an electronically-controlled counter-pressure valve (60) that enables backpressure in a return line (36) of the system to be varied by a control unit (64). The system allows active control of the pressure in the return line to produce different return pressures for different situations. A higher return line pressure may be set to improve make-up or recirculating flow through an anti-cavitation valve (50). This may improve controllability of functions that benefit from backpressure, such as lowering loads (12). The control unit that controls the counter-pressure valve may take into account any of a wide variety of possible inputs when setting the counter-pressure valve.