Actuator operating signal sensor

摘要

A device for sensing actuator operating signal in a hydraulic system is disclosed. The device has auxiliary valves directly coupled to the directional control valves respectively, the internal lines of which auxiliary valves are opened or become orifices in accordance with positions of spools of their associated directional control valves. A fluid line extends from a hydraulic pump to a return tank after passing the auxiliary valves in a series. The device also has two means for detecting fluid pressure at two given points along the fluid line. An additional orifice is formed in the hydraulic line between the auxiliary valves and the pressure detecting means is provided in the hydraulic line before and after the additional orifice.