THE EMPLOYEE POSITIONED HIS DUMP TRUCK UNDERNEATH A BIN AND APPLIED THE TROLLEY BROKE BEFORE OPENING THE TRUCK DOOR TO OPEN THE BIN. WHILE LEANING OUT OF THE CAB, HIS KNEE BUMPED THE TROLLEY B RAKE HANDLE CAUSING THE TRUCK TO DRIFT BACKWARDS. HIS SHOULDER BECAME PINCHED BETWEEN A STEEL BEAM AND THE TRUCK DOOR.