WHEEL GP-REAR 3178379 - Caterpillar

Illustration 1 g00521611
Dual Horsepower Mechanism ( Type VII) (1) Setscrew (2) Oil gallery (3) Seal (4) Spring (5) Piston Assembly (6) Valve cavityThis is the second type of two types of dual horsepower mechanisms. The dual horsepower mechanism is used to limit horsepower under certain operating conditions. Unlike the Type VI dual horsepower mechanism, the internal governor linkage contacts the torque cam in both low horsepower mode and high horsepower mode.To activate low horsepower, the solenoid must be de-energized. The solenoid is located in valve cavity (6). When the solenoid is de-energized oil is allowed to flow into oil gallery (2). This oil pressure acts upon piston assembly (5) and spring (4) by pushing the piston assembly until the full stroke of the piston is reached. This limits the movement of the internal governor linkage in the fuel on direction so there is less fuel output and less horsepower. The rack position for low horsepower is set with setscrew (1) which is located in the dual horsepower mechanism.To activate high horsepower, the solenoid must be energized. When the solenoid is energized, oil is restricted from entering oil gallery (2). Instead, oil that is already in the oil gallery flows back through the solenoid into the governor. This reduces the pressure against piston assembly (5). Spring (4) moves the piston assembly away from the internal governor linkage. This allows the internal linkage to move further in the fuel on direction which provides more horsepower. The rack position for high horsepower is set with setscrew (1) that is located in the dual horsepower mechanism.