VARIABLE REGENERATION CIRCUIT

PURPOSE:To simplify construction of a regeneration valve, which supplies pressure oil to the actuator of a hydraulic cylinder and the like and makes selective regeneration of the return oil, and to lessen passing resistance of a regeneration pressure oil passage while in process of regeneration and in operation. CONSTITUTION:A regeneration functional valve 27, which is provided with a directional control valve 24, which has its internal passage 34 usually closed and closes its internal oil passage by linking with a command signal operating an oil pressure switching valve 3 to the direction where pressure oil is supplied to a head side oil sac C of a hydraulic cylinder 2, in the midway of line pipes 35, 36 connecting the hydraulic directional control valve 3 and the hydraulic cylinder 2 together, a check valve 10, which forms a free passage only towards the line pipe 33 lead to a head side oil sac C of the hydraulic cylinder 2 from a delivery port of the directional control valve 24, and an inlet port lead to a line pipe 34 connecting a rod side oil sac D of the hydraulic cylinder 2 and the oil pressure switching valve 3 together, is provided independently of the oil pressure switching valve 3. Thus the construction of the valve itself can be simplified and the passing resistance of the regeneration oil pressure circuit in the course of regeneration can be kept to the least.