Safety mechanism for a vertical reciprocating conveyor

Abstract

A vertical reciprocating conveyor having a safety mechanism for automatically locking the conveyor at an elevated level. The conveyor comprises a cargo-supporting carriage which is guided for movement between a lower level and an upper level on a supporting structure. A drive mechanism which can take the form of a hydraulic cylinder unit is operably connected to the carriage and moves the carriage from the lower to the upper level. As the carriage moves upwardly, it travels slightly beyond the upper level to a third higher location where the carriage engages a limit switch which acts to discontinue operation of the hydraulic system, enabling the carriage to lower by gravity. At this third location, a pair of locking bars that are pivoted to the sides of the carriage, are moved toward a locking position so that as the carriage moves downwardly, the locking bars engage ledges on the supporting structure thereby locking the carriage at the upper level. To move the carriage from the upper level back to the lower level, the cylinder unit is actuated causing the carriage to move upwardly from the upper level to the third higher location. At the third location, the limit switch is actuated to terminate operation of the hydraulic system, enabling the carriage to move downwardly and simultaneously the locking bars are moved to the release position, so that the carriage can move downwardly through the upper level back to the lower level.