MAINTENANCE MECHANIC REMOVING AND INSTALLING AN ELECTRIC MOTOR ON SCREEN DECK ON PORTABLE SCREENING PLANT. ANOTHER EMPLOYEE WAS OPERATING A CRANE TO LIFT THE MOTOR. HE PLACED HIS HAND BETWEEN THE SNATCH HOOK AND THE SCREEN FRAME AND PLUMBING TRIED TO STOP THE SNATCH HOOK AND HIS HAND WAS PUSHED AGAINST THE END OF A BALL VALVE.