A farmer died when a corn planter collapsed on him as he tried to change a tire. He had been moving the planter to another field when he noticed one of the road tires was flat. He stopped in the field and began to change it. He did not brace the planter, nor did he use the mechanical safety catch designed to keep the hydraulic cylinder extended during maintenance. He crawled under the planter and loosened the bolts on the wheel but could not get them off. In an attempt to relieve the pressure on the flat, he loosened the fitting connected to the wheel’s hydraulic cylinder. He apparently expected the outside wheel cylinder to hold that side of the planter up while he relieved the ground pressure on the inside wheel, not realizing that both wheel cylinders were connected. When the line fitting came off, hydraulic fluid shot out and the entire right side of the planter fell on the victim. He was killed instantly by a penetrating head injury from the edge of the frame. He was not found until the next day, when an employee noticed he had not been home to do the chores.

Even when equipment is turned off and apparently at rest, it can still be under hydraulic pressure. Therefore, equipment parts supported by hydraulics have to be mechanically blocked during maintenance, and hydraulic pressure must be relieved before working on any part of the system.