EE AND COWORKER DROVE TO THE SALVAGE YARD TO PICK UP- A 'T' BEAM/ EE WAS BEHIND THE 'A' FRAME TRUCK SECURING A CHOKER TO THE BEAM. COWORKER WAS BACKING THE TRUCK UP. COWORKER'S FOOT SLIPPED FR OM BRACE & HIT THE GAS. THE TRUCK STRUCK EE AND KNOCKED HIM TO THE GROUND.