Ballet shifter

Claim 1

A pallet shifter for transferring pallets from one conveyor having a discharge end to another conveyor having a receiving end, comprising: driving lever means, having a midpoint and opposite ends, carried for reversible rotation about said midpoint on a horizontal shaft journalled in a fixed frame and driven by reversible driving means; pallet carriers pivotally carried about horizontal axes on said opposite ends of said driving lever means for movement thereby between the discharge and receiving ends, respectively, of two pallet carrying conveyors moving in opposite directions so that when one pallet carrier is at the discharge end of one conveyor to receive a pallet therefrom, the other pallet carrier is at the receiving end of the other conveyor to discharge thereto a pallet previously received from the one conveyor; and stabilizing lever arrangements for maintaining said pallet carriers substantially horizontal during their movements between the conveyor ends, each of said arrangements including a first stabilizer lever having one end thereof pivotally connected to said fixed frame and the other end thereof to the respective carrier so that the axis of said shaft, the axis of the pivotal connection of the respective carrier to an end of said driving lever means and the axes of the two pivotal connections of said first stabilizing lever and the structural parts of said frame, said driving lever means, said respective carrier and said first stabilizing lever extending between said axes define a parallelogram linkage and a second stabilizing lever having one end thereof pivotally connected to said driving lever means and the other end thereof to said first stabilizing lever so that the axis of said shaft, the axes of the two pivotal connections of said second stabilizing lever and the axis of the pivotal connection of said first stabilizing lever to said frame and the structural parts of said frame, said driving lever means, said second stabilizing lever and said first stabilizing lever extending between said axes define a second parallelogram linkage arranged to be stable when said first parallelogram linkage becomes unstable when all the pivot axes thereof are arranged in a straight line.