Abstract: Conveyor apparatus comprises an endless conveyor operative to convey workpieces past a number of processing stations. The workpieces are conveyed in seats of the conveyor, each of the seats being designated to receive a workpiece which is at a predetermined stage in the process. Means are provided to sense the presence of filled and empty seats and to control workpiece removal and depositing means associated with the processing stations so that workpieces are only removed from, and deposited in, the appropriate designated seats.