STUMP-OUT APPARATUS FOR A DOCK LEVELER

摘要

A closed loop reciprocating fluid circuit apparatus (150) for mechanically powered and electromechanically powered dock levelers (100), which may be mounted at a forward edge of a dock leveler to selectively engage the dock leveler during pivotal downward movement of a deck, is provided. The apparat us may include a header (158) extending from a fluid chamber (152) (e.g., a hydraulic cylinder), where the header may selectively engage the deck, withi n the range of dock leveler heights, including below dock level and above dock level operating positions. The hydraulic cylinder may be vertically oriented and coupled to a fluid accumulation chamber (156), such that vertical moveme nt of the header in response to the deck's downward movement causes fluid displacement into the accumulation chamber. That displacement may be in a horizontally oriented fluid chamber having a piston that reacts to the fluid transfer. Alternatively, that displacement may be into a resilient fluid chamber such as a bladder (504) housed within a suitable container, or a flu id chamber (404) such as a fluid reservoir with a breather (410), for air volum e compensation. The hydraulic cylinder and header may be urged to the extended position, for example by extension springs (308) acting on a piston within t he fluid accumulation chamber, or by a pull chain or latch (420) coupled to the cylinder and the upward movement of the deck. A flow control valve (304), e.g., a velocity fuse or solenoid valve, is connected between the cylinder a nd the fluid accumulation chamber to respond to free fall of the deck. Resettin g to normal operation after free fall detection may occur after load removal from the deck and by movement of the cylinder to the opposite direction or b y electrical control input to the control valve.