Abstract: On May 12, 1991, Employee #1 and two coworkers, of Nakase Brothers Nursery, were each driving tractor trailer rigs along a highway. One of the trucks hit an object in the road, damaging a clamp on the air brake chamber and allowing air to escape from the system. At approximately 9:00 p.m., Employee #1 was trying to repair the braking system and loosened the damaged clamp. The spring cage cap flew off and struck him in the head, causing a severe skull injury. Employees had been instructed not to attempt mechanical repairs, but to radio in and wait for a mechanic. They had also received training and safety orientation from the employer and from Ryder Systems.