EE WAS PULLING ON A WRENCH DISASSEMBLING A MOTOR WHEN THE PRESSURE RELEASED SUDDENLY. HE LOST HIS BALANCE & FELL AGAINST A TOOL IN THE TRUCK SHOP STRIKING HIS LOWER BACK ON A CORNER OF THE MAC HINE. HE HAD HIS BACK EXAMINED AT THE LOCAL E.R.& WAS PRESCRIBED MEDICATION FOR LOWER BACK PAIN.