VARIABLY REGENERATING CIRCUIT

PURPOSE:To improve strength of a spool and to decrease passing resistance in a regenerative pressure oil passage, by providing only the regenerative function part in a hydraulic cylinder actuating variably regenerating circuit valve independently of a hydraulic pressure selector valve so that the construction of the variably regenerating circuit valve can be simplified. CONSTITUTION:The control lever of a pilot valve 29 is pulled in a direction J, and if a signal pressure is generated in a pilot oil path 30, a hydraulic pressure selector valve 3 is switched to a position G, and also a selector valve 24 in a regenerative function valve 27 is simultaneously switched from a position E to a position F via a pilot oil path 32. Accordingly, pressure oil, which passes through a port A and oil paths 35, 33, is allowed to flow into the head side oil chamber C of a hydraulic cylinder 2. And when the hydraulic cylinder 2 bears a small load in the time of its extension, since a notched hole is blocked with no rightward movement of a small contour spool, a regenerating circuit is formed, so that return oil from a rod side oil chamber D may pass through an oil path 34 and an F position passage of the selector valve 24, pressing a check valve 10 to be opened and joining the oil path 33.