FUEL INJECTION EQUIPMENT There are three methods commonly used for the mechanical injection of fuel (at the proper amount, time, and duration) into the cylinders of a diesel engine. These methods are as follows: 1. Pump controlled (jerk pump) 2. Distributor 3. Unit injector NOTE: A fourth method, known as pressure-time (PT) uses unit injectors. This method is unique to Cummins diesel engines and is not considered to be common; therefore, it will not be explained in this rate training manual. The three methods listed above will be explained in the sections that follow. JERK PUMP FUEL INJECTION SYSTEM Jerk pump fuel injection systems consist of high-pressure pumps and pressure-operated spray valves or nozzles that are separate components. In some engines, such as the Alco, there is only one pump and one nozzle for each cylinder. In other engines, such as the Fairbanks-Morse opposed-piston engine, each cylinder has two pumps and two nozzles. Most of the injection event is carried out by t...
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