Abstract: At approximately 5:25 a.m. on July 16, 2003, Employee #1 was reinstalling an air conditioning window unit. He was standing on the platform of a battery operated stacker, Presto Model Number B766-1500, Serial Number 93185. Employee #2 was standing on an A-frame ladder. The stacker was battery operated with 1500 lbs. capacity. It was hydraulic and man powered. It was used at this facility to lift, transport, and lower die into machinery. The AC unit weight was 139 lbs., and measured 27 in. by 27 in. by 17 in. The stacker's platform was at its maximum elevation of 65.5 in. The lower level of the AC unit housing was 75.5-in high. Employees #1 and #2 had to lift the unit another 10 in. as they pushed it in. As Employees #1 and #2 tried to push the unit in, the stacker rolled and slid back. The floor was tiled with very low surface of friction. There was a heavy metal cabinet against the wall, measuring 51-in. high by 18-in deep. It was located under the AC unit housing. Employee #1 fell off the platform with the AC unit landing on him. The ladder tipped over with Employee #2 on it. Employee #2 sustained minor injuries, and Employee #1 sustained a serious injury to his left knee. Employee #1 was hospitalized and treated for a dislocated knee.