SERIES 60 SERVICE MANUAL THE FOUR CYCLE PRINCIPLE FOR DIESEL ENGINES The diesel engine is an internal combustion engine, in which the energy of burning fuel is converted into energy to work the cylinder of the engine. In the diesel engine, air alone is compressed in the cylinder, raising its temperature significantly. After the air has been compressed, a charge of fuel is sprayed into the cylinder and ignition is accomplished by the heat of compression. The four piston strokes of the cycle occur in the following order: intake, compression, power and exhaust. See Figure 1.
Figure 1 The Four Stroke Cycle (Diesel) Intake Stroke During the intake stroke, the piston travels downward, the intake valves are open, and the exhaust valves are closed. The down stroke of the piston facilitates air from the intake manifold to enter the cylinder through the open intake valve. The turbocharger, by increasing the air pressure in the engine intake manifold, assures a full charge of air is available for the cylinder. The intake charge consists of air only with no fuel mixture. (Rev. 2005) All information subject to change without notice. 4 6SE483 0507 Copyright © 2005 DETROIT DIESEL CORPORATION