TM 9-2350-256-34-2energy into rotary motion and torque. This torque is then transmitted to the hoist winch. (See (b) above).(e) Hoist winch brake cylinder (fig. 1-7). The hoist winch brake cylinder is located on the brake housingat the front of the hoist winch. Within the cylinder is a piston which is springloaded to the applied position. Thepiston exerts force on the brake drum to prevent drum movement in the HOLD position. The piston is backedoff, and the brake released, by introducing hydraulic pressure into the brake cylinder.(2) Operation.(a) Hoist winch hydraulic motor operation. Hoist winch hydraulic motor operation is the same as mainwinch hydraulic motor operation. Refer to paragraph 1-3b.(b) Winch gear train operation. When the hoist winch control valve is in the RAISE position, thehydraulic motor rotates in the counterclockwise direction (fig. 1-9) and drives the winch bevel gear and piniongear, causing them to rotate counterclockwise. (Gear direction of rotation is determined by viewing the hoistwinch from the brake assembly side). The pinion gear is splined to the pinion shaft and thus drives the shaft inthe same direction. As the pinion shaft rotates, the geared end of the shaft engages the low speed gear andthe pinion gear engages the high speed gear, both of which rotate freely around the brake shaft. Between thehigh and low speed gears, and splined to the brake shaft, is the gear clutch. The external teeth of the gearclutch are meshed with the internal teeth of the gear coupling. This couplingis positioned either left or right inorder to couple the gear clutch with either the high or low speed gear, thus causing the brake shaft to rotate inthe clockwise direction. The splined end of the brake shaft drives the brake drum assembly, while the gearedend of the shaft meshes with and drives the drum gear in a counterclockwise direction. The drum gear thenrotates the cable drum in a counterclockwise direction to raise the winch cable. Placing the hoist winch controlvalve in the LOWER position causes the hydraulic motor to rotate in a clockwise direction. All gears thenrotate in the opposite direction from that described above and the cable drum rotates clockwise to lower thewinch cable.1-11
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