BOOT 1414852 - 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.Clean inlet air from the air cleaner and from the silencer is pulled through air inlet (4) into the turbocharger compressor by the turbocharger compressor wheel (5). The rotation of the turbocharger compressor wheel causes the air to compress. The rotation of the turbocharger compressor wheel then forces the air through an elbow to the aftercooler (2). The aftercooler lowers the temperature of the compressed air before the air goes into the air plenum. This cooled and compressed air fills the air plenum and the inlet chambers in the cylinder heads. Air flow from the inlet chambers into the cylinders is controlled by the inlet valves.There are two inlet valves and two exhaust valves for each cylinder. Make reference to Valve System Components. The inlet valves open when the piston moves down on the inlet stroke. The cooled, compressed air is pulled into the cylinder from the inlet chamber.The inlet valves close and the piston starts to move up 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 starts. The force of the combustion pushes the piston downward on the power stroke. When the piston moves upward 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 piston makes the exhaust stroke, the exhaust valves close and the cycle starts again.Exhaust gases from the exhaust manifold go into the turbine side of the turbocharger. The exhaust gases cause the turbocharger 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).