Abstract: On February 20, 2003, Employee #1 was working at a concrete mixing batch plant, where sand, cement, and aggregate are mixed in the desired proportion and discharged through a hopper opening to load trucks. There are two discharge hoppers, left and right alleys. They decided to increase the discharge rate of the right alley. The hopper is at a height of about 12 ft. A 6-in. by 6-in. butterfly valve at the discharge opening controls the concrete discharge. The valve movement is controlled by a hydraulic ram, which in turn is actuated by the travel of a 1-in. bolt. Employee #1 was adjusting the travel of the 1-in. bolt while standing on a platform. The bolt was not rotating properly and he asked a coworker, his assistant, on the ground to get some lubricating oil. The coworker misunderstood what he was asked and went to the plant office and told the Plant Manager, operating the control console, to start the concrete mixture loading. As the plant was started, Employee #1's right hand finger was caught between the ram and bolt and was amputated.