Patent ID: 7752842
Filing Date: 2010-07-13
Classification: B66F,E02F,F15B

Abstract:
1. A circuit for controlling a double-action hydraulic drive cylinder having a piston separating a piston space from a rod space, wherein hydraulic oil can be supplied to the piston space while hydraulic oil simultaneously flows out of the rod space, and hydraulic oil can be supplied to the rod space while hydraulic oil simultaneously flows out of the piston space, the circuit comprising: a directional control valve which actuates said hydraulic cylinder, the directional control valve comprising working ports A and B, a pump port P, and a tank port T, wherein the directional control valve has a neutral position in which the pump port P is blocked and the two working ports A, B are connected to the tank port T; a parallel circuit comprising a pressure-limiting valve and a controllable load-holding valve connected to the piston space in parallel; a regeneration check valve connected in series between the parallel circuit and the rod space, the regeneration check valve, the pressure-limiting valve, and the controllable load-holding valve check valve being connected to each other at a connection point; a first precharge valve connected between the working port A and the connection point, the first precharge valve permitting flow from the connection point to the working port A; a first bypass check valve in parallel with the first precharge valve and the load-holding valve, the first bypass check valve permitting flow from the working port A to the piston space; and a second precharge valve connected in series with the directional control valve between the tank port P and the rod space.