Abstract: In a self-sealing coupling with a bypass for a hydraulic circuit designed to connect a hydraulic sub-circuit to a midway portion of a main circuit of a hydraulic device, there is provided a coupling body with an input passage, an output passage, an input passage side and an output passage side self-closing valves and a bypass valve. The bypass valve is provided with a cylindrical valve element which is reciprocatively slidable within either one of said input passage and said output passage so as to open and close that one passage relative to a bypass provided therebetween. The cylindrical valve element is adapted to be moved together with the self-closing valve element provided in the one passage, to be shifted to a bypass valve opening position where the bypass is opened by the cylindrical valve element valve closed condition.

Abstract: In a selective control device for plural kinds of oil-hydraulic actuators comprising an actuator selective valve for selecting an operative oil-hydraulic actuator from among plural kinds of oil-hydraulic actuators and a directional control valve for operating the selected actuator extendedly and retractedly, the actuator selective valve is provided with a quick extensional position which functions to connect an extensional pressure port thereof to a bottom side oil chamber of the selected actuator and also to connect a head side oil chamber to the bottom side oil chamber in order to extend the selected actuator quickly. The construction of the actuator selective valve eliminates a quick extensional valve adopted in a prior oil-hydraulic control device.