LATCH-WINDOW 4592760 - Caterpillar

Illustration 1 g00281646
Air inlet and exhaust system
(1) Exhaust manifold
(2) Aftercooler
(3) Engine cylinder
(4) Air inlet
(5) Turbocharger compressor wheel
(6) Turbocharger turbine wheel
(7) Exhaust outlet Turbocharger compressor wheel (5) pulls clean inlet air from the air cleaners through air inlet (4) into the turbocharger compressor. The rotation of the compressor wheel compresses the air. The rotation of the compressor wheel forces the air into aftercooler (2). The aftercooler reduces the temperature of the compressed air before the air flows into the inlet chambers in each cylinder head. Air flow from the inlet chamber into the cylinder heads is controlled by the inlet valves.There are two inlet valves and two exhaust valves for each cylinder. Refer to Systems Operation, "Valve Mechanism". The inlet valves open when the piston moves down on the inlet stroke. The cooled, compressed air is pulled into the cylinder.The inlet valves close and the piston moves upward on the compression stroke. When the piston is near the top of the compression stroke, fuel is injected into the cylinder. The fuel mixes with the air and combustion occurs. The force of the combustion pushes the piston downward on the power stroke. When the piston moves upward again, the piston is on the exhaust stroke. The exhaust valves open and the exhaust gases are pushed through the exhaust port into exhaust manifold (1). After the exhaust stroke, the exhaust valves close and the cycle starts again.Exhaust gases from exhaust manifold (1) go into the turbine side of the turbocharger. The exhaust gases cause turbine wheel (6) to turn. The turbine wheel is connected to the shaft that drives the turbocharger compressor wheel (5). The exhaust gases exit through the exhaust outlet (7).