Abstract: An improved stacker assembly includes a base assembly and a hollow mast which extends upwardly from the base assembly. A cap assembly is disposed on the upper end portion of the hollow mast. A carriage is movable up and down along the mast to raise and lower a load. The base assembly includes an upwardly extending mast support assembly which is telescopically received in the lower end portion of the hollow mast. The mast support assembly includes a gripper assembly which is operable to grip the inside of the lower end portion of the hollow mast. The cap assembly includes a downwardly extending cap support which is telescopically received in an upper end portion of the hollow mast and is expandable to grip the inside of the hollow mast. In the event of a loss of tension in a support cable for the carriage, a brake assembly on the carriage grips elongated brake bars which are separate from the mast to support the carriage.

Abstract: A novel dual mast storage and retrieval vehicle comprising structure which maintains each mast essentially vertical as variably weighted heavy loads are placed on a carriage disposed between the masts. Each mast is disposed near the center of a separately supported base such that bending of the base under such loads induces little off-vertical deflection to the mast. The separately supported bases are coupled by a connector which comprises cross-aisle and vertical degrees of freedom but is strictly constrained in the down-aisle direction. In the currently preferred embodiment, two down-aisle drive motors, in master/slave relationship, provide a synchronous drive for the vehicle. Further, interconnecting joints a strut at the top of the masts and of the carriage comprise hinges which resist propagation of mast induced moments caused by beam deflection or vehicle dynamics.