Fluid line coupling for fluid actuated extensible structure

Abstract

A lift truck having a particular type of upright, namely, a triple stage upright having a fixed upright section, two telescopic sections, and a load carrier mounted on the inner telescopic section. A primary lift cylinder and chain assembly is mounted from and elevatable with the inner upright section and is connected with the load carrier to elevate it with the inner section, and a secondary lift cylinder is supported from the truck and connected to elevate the telescopic sections with the primary cylinder and load carrier. A fluid conduit is provided between the primary lift cylinder and secondary lift cylinder, a first portion of the fluid conduit having a first valve interposed therein is operatively associated with the primary lift cylinder and is selectively engageable with a second valve interposed in a second portion of the fluid conduit and operatively connected with the secondary lift cylinder. When the primary lift cylinder is retracted relative to the secondary lift cylinder, the coupling comprised by the first and second valves is in its fluid engagement position, but is not in its fluid engagement position when the primary lift cylinder is extended. The coupling has self-centering alignment capability. Fluid retained in the second valve is protected from contamination by an overlying cover plate when the primary lift cylinder is extended.