Hose rupture control valve unit

摘要

A hose rupture control valve unit comprises a housing (100) provided with two input/output ports (12). One input/output port (1) is directly attached to a bottom port of a hydraulic cylinder (102), and the other input/output port (2) is connected to one of actuator ports of a control valve via an actuator line (105). Within the housing (100), there are provided a poppet valve body (5) serving as a main valve, a spool valve body (6) serving as a pilot valve which is operated with a pilot pressure supplied as an external signal from a manual pilot valve (108), thereby operating the poppet valve body (5), and a small spool (7) having the function of an overload relief valve. The above construction reduces the number of components arranged in a flow passage through which a hydraulic fluid passes at a large flow rate, and hence a pressure loss. A further reduction in overall size and production cost of the valve unit is achieved.