EDGE GP-BIT & CUTTING 4346371 - Caterpillar

Illustration 1 g01947658
The boost control valve
(1) Opening to the carburetor
(2) Piston
(3) Vent hole
(4) Spring
(5) Air line to the inlet of the turbocharger compressor
(6) Opening from the turbocharger The boost control valve is located in the air supply line between the turbocharger and the carburetor air inlet. The valve consists of the housing, piston (2), and spring (4). The tension from the spring forces the piston to open until the air pressure from the turbocharger exceeds the spring tension force. As the demand on the engine increases, the volume of inlet air from the turbocharger increases. The increased air volume increases the air pressure in the air inlet. As the air pressure from the turbocharger increases, the piston is forced into the valve body. As the piston enters the valve body, the flow of turbocharged inlet air to the engine becomes restricted.For the piston to operate correctly, the spring cavity must be sealed from the pressurized air in the air inlet. The spring cavity must be allowed to vent to atmospheric pressure. Passage (3) is cast through the valve body and into the spring cavity. Air line (5) is connected to this passage. The air line allows the free flow of filtered air between the spring cavity and the inlet air passage. The piston is allowed to move freely within the spring cavity. The passage and air line must never become restricted by dirt or debris.