PULLEY-IDLER 7W3850 - Caterpillar

Illustration 1 g00350753
Callouts (1) through (11) follow the air flow from the air cleaner to the muffler. (1) Air cleaner (2) Clean inlet air (3) Turbocharger (4) Clean, hot, pressurized inlet air (5) Air-to-air aftercooler (chassis assembly) (6) Clean, cool, pressurized air (7) Inlet manifold (8) Exhaust manifold (9) Hot exhaust gases (10) Cooler exhaust gases (11) Muffler (12) Fan (13) Radiator
Illustration 2 g00340186
Schematic of Air Inlet and Exhaust System (8) Exhaust manifold. (5) Air-to-air aftercooler core. (14) Exhaust valve. (15) Inlet valve. (7) Inlet manifold (cylinder head). (16) Air piping from turbocharger to aftercooler. (17) Exhaust outlet. (18) Air inlet. (19) Compressor side of turbocharger. (20) Turbocharger shaft. (21) Turbine side of turbocharger.In an air-to-air aftercooler system, compressed, turbocharged air is directed to a mounted cooler in front of the radiator. Air (ambient temperature) is moved across the aftercooler. This allows the aftercooler to lower the inlet valve's air temperature to approximately 43°C (109°F). The air then flows to inlet manifold (7), which is part of the cylinder head. The cooling of the inlet air increases combustion efficiency, which provides two main benefits:
Lower fuel consumption
Increased horsepower outputClean inlet air (2) from air cleaner (1) is pulled through air inlet (18). This inlet air is pulled into the compressor side of turbocharger (19) by rotating compressor wheel (22). The rotating compressor wheel pressurizes the inlet air. Consequently, this compressor wheel heats up the inlet air. This pressurized, hot inlet air is then forced through the air piping from the turbocharger to aftercooler (16). The air-to-air aftercooler core (5) then cools the inlet air. This cool air provides dense, high pressure air to inlet manifold (7) in the cylinder head. When inlet valves (15) open, the cool, dense, high pressure air flows into the combustion chamber. At this point, the cool air mixes with the fuel spray that has been injected for combustion during the compression stroke.When exhaust valves (14) open, hot exhaust gases flow into exhaust manifold (8). These hot exhaust gases flow to the turbine side of the turbocharger (21) and out exhaust outlet (17). When the hot gases pass through both the turbine wheel and the compressor wheel (air inlet side), the exhaust gases' energy turns these wheels via turbocharger shaft (20) .Turbocharger
Illustration 3 g00365373
Turbocharger Cartridge (22) Turbocharger compressor wheel (23) Ring (24) Turbine housing (25) Turbocharger bearing (26) Oil inlet port (27) Ring (28) Deflector (29) Oil outlet port (30) Ring (31) Turbocharger bearing (32) RingThe turbocharger is mounted to exhaust manifold (8). All the exhaust gases flow from exhaust manifold (8) through the turbocharger. The exhaust gases then flow into turbine housing (24) through the exhaust inlet. These gases push the blades of turbine wheel. The turbine wheel is connected by a shaft to turbocharger compressor wheel (22). Therefore, the exhaust gases cause the two wheels to turn at very high speeds.Clean air from the air cleaner is pulled through the air inlet (18) by the rotation of turbocharger compressor wheel (22). The action of the