Abstract: Employee #1 and his son were in the process of replacing the packing on two nitrogen- and grease-filled track adjusting cylinders of a UTT 180 EX Hitachi log loader. Employee #1 and his son had removed the nitrogen and grease and were using compressed air to move the rod and piston up the cylinder to a point where they could remove them and replace the packing. Employee #1 and his son had completed this task on one of the cylinders when Employee #1 told his son to go see if the parts had arrived to complete the job. When the son returned, he found Employee #1 slumped over a chair and bleeding severely from his head. He was transported to Salem Memorial Hospital and hospitalized. There were no witnesses to the accident. The rod and piston weigh more than 100 pounds and were lying on the floor. There was a hole in the 16 foot 1 inch high ceiling, indicating that it had been struck by the rod and piston.