SELF-REVERSING HYDRAULIC CONTROL MECHANISM

摘要

TITLE SELF-REVERSING HYDRAULIC CONTROL MECHANISM A self-reversing hydraulic control mechanism directs the flow of inlet and exhaust fluids into and out of a reciprocating pumping unit. The mechanism has cooperating poppet valves with fluid passages thereto disposed so that a difference in pressure between inlet and exhaust fluids exerts a holding force. This force maintains the valves in their set position until overcome by an altering force, which is developed by travel of a piston of the pumping unit.