Linked bidirectional lock for cover type hydraulic support first and second level protecting boards

The utility model discloses a linkage reversible lock used in the first-stage and second-stage protecting side plates of the shielding type hydraulic supporting frame. The linkage reversible lock comprises a valve body; control units with the identical structure are respectively arranged at the both sides of the longitudinal central line in the valve body; the control units comprise fluid outlets which are vertically arranged at the upper sides of the valve body downwards, pilot operated check serial valve mounting holes and pilot operated check serial valves arranged inside the pilot operated check serial valve mounting holes, wherein, the fluid outlets are communicated with the upper valve cavities of the check valves through oil ducts; the lower valve cavities of the check valves of the two control units are mutually communicated through the oil ducts, and piston sleeves are arranged on the valve rods positioned in the lower valve cavities of the pilot operated check serial valves; a switching valve is arranged in the valve body, the two fluid inlets of the switching valve are respectively communicated with the two fluid inlets arranged on the left and right side walls of the valve body; the fluid outlets of the switching valve are respectively communicated with the lower valve cavities of the check valves and the piston sleeve bottoms in the two control units. The linkage reversible lock has the advantage that when the first-stage protective side hoisting jack is extended or retracted, the second-stage protective side hoisting jack always retains an extended state.