SEQUENTIAL PIGGYBACK CYLINDERS FOR EXTENDABLE BOOM CRANE

摘要

A crane boom has three telescoping sections which move consistently in a sequential pattern between extended and retracted positions. When extending, the outer section moves first, followed by the middle section. When retracting, the middle section moves first, followed by the outer section. A pair of hydraulic actuators with a series of valves control the extension and retraction of the outer and middle boom sections.