EE AND CO-WORKER HAD BEEN DISASSEMBLING ROTARY GEAR BOX TO FIND ORIGIN OF PROBLEM. THE COVER PLATE WAS STANDING ON END ON FLOOR OF SHOP WHEN IT WAS EITHER BUMPED OR BRUSHED BY A GEAR ATTACHED TO OVERHEAD CRANE. THE COVER PLATE FELL OVER ON EE'S FOOT, CO-WORKER WAS WASHING A GEAR AT PARTS WASHER WITH HIS BACK TO INJURED EE.