COVER-VALVE MECHANISM 4490818 - Caterpillar

Illustration 1 g00987178
Flow diagram of the air inlet and exhaust system (1) Turbocharger (2) Exhaust (3) Air inletThe components of the air inlet and exhaust system control the quality of air and the amount of air that is available for combustion.Naturally aspirated engines pull outside air through air inlet (3) of an air cleaner directly into the inlet manifold. The air flows through the inlet manifold which directs an even distribution of the air to each engine cylinder. The air is pulled into the engine cylinder during the intake stroke of the piston. Fuel is mixed with the air in the engine cylinders during the compression stroke. After the fuel combustion occurs in the engine cylinder, the exhaust gases flow directly to the outside air through exhaust (2) .Turbocharged engines pull outside air through air inlet (3) of an air cleaner into the air inlet of turbocharger (1). The suction is caused by the turbocharger compressor wheel. Then, the turbocharger compressor wheel compresses the air. The air flows through the inlet manifold which directs an even distribution of the air to each engine cylinder. The air is pulled into the engine cylinder during the intake stroke of the piston. Fuel is mixed with the air in the engine cylinders during the compression stroke. After the fuel combustion occurs in the engine cylinder, the exhaust gases flow to the exhaust manifold. The exhaust gases from the exhaust manifold enter the turbine side of the turbocharger in order to turn the turbocharger turbine wheel. The turbine wheel is connected to the same shaft that drives the compressor wheel. Exhaust gases from the turbocharger pass through the exhaust outlet and to exhaust (2) .Each piston makes four strokes for one complete cycle in two revolutions of the crankshaft.
IntakeDuring the intake stroke, the piston moves down and air is drawn into the cylinder through the open inlet valve.
CompressionDuring the compression stroke, the valves are closed and the piston moves up in the cylinder in order to compress the air. As the air is compressed, the temperature increases. As the piston nears the top of the stroke, fuel is injected into the combustion chamber on top of the piston. The fuel mixes with the hot compressed air in order to cause combustion.
PowerDuring the power stroke, the valves are closed as the forces from combustion push the piston and connecting rod down turning the crankshaft.
ExhaustDuring the exhaust stroke, the inertial force of the turning flywheel helps continue the rotation of the crankshaft in order to push up the piston in the cylinder. This action forces the burned gases out of the exhaust valve. This completes the four strokes of the piston.Turbocharger (if equipped)
Illustration 2 g00302786
Components of a turbocharger (typical example) (1) Air inlet (2) Compressor housing (3) Compressor wheel (4) Bearing (5) Oil inlet port (6) Bearing (7) Turbine housing (8) Turbine wheel (9) Exhaust outlet (10) Oil outlet port (11) Exhaust inletThe turbocharger is mounted on the exhaust manifold. All the exhaust gases from the