PLATE 2540060 - Caterpillar

Fuel that is under high pressure from the fuel injection pump flows through the orifice in fuel inlet (3). The fuel flows around needle valve (9) and into nozzle (10). The fuel applies pressure against needle valve (9) and pressure spring (5). When the force of the fuel pressure is greater than the force of pressure spring (5), needle valve (9) will raise. Fuel under high pressure will pass through orifices (11) into the cylinder. The force that is created by the pressure of the fuel then becomes less than pressure spring (5) and needle valve (9) will move quickly to the closed position.Needle valve (9) has a close fit with the inside of nozzle (10). This fit creates a positive seal for needle valve (9).When the fuel is sent into the cylinder, a small quantity of the fuel will leak past the valve guide. This fuel provides lubrication to the moving parts of the fuel injection nozzle. The fuel then passes through a leak off passage in body (6) to fuel return (1) to the fuel tank.Fuel Injection Pump
Illustration 3 g00531642
Typical example of the fuel injection pump components
(1) Control lever
(2) Flyweights
(3) Flow adjusting screw
(4) Drive shaft
(5) Governor lever
(6) Solenoid
(7) Housing for delivery valves
(8) Control sleeve
(9) Feed pump
(10) Holder for roller
(11) Plunger
(12) Cam disk
(13) Timer
(14) Plunger spring
(15) Delivery valve The fuel injection pump is fully closed and pressurized. The fuel injection pump sends the correct amount of high pressure fuel through the fuel injection nozzles to the individual cylinders at the correct time. The correct time is near the end of the compression stroke. The fuel injection pump measures the amount of fuel that is delivered to the fuel injection nozzles. The amount of fuel is controlled by adjusting the governor setting, the position of the accelerator, or the throttle control.The fuel lines to the fuel injection nozzles are equal lengths. Fuel lines that are equal length ensure even pressure and the correct injection timing at each fuel injection nozzle.During operation, excess fuel is used for cooling and lubrication. The fuel flows through the housing of the fuel injection pump and back to the fuel tank. Return lines also carry away air that is trapped in the fuel injection nozzles or in the housing of the fuel injection pump.
Illustration 4 g00531644
Typical example of a cross section view of a fuel injection pump
(4) Drive shaft
(6) Solenoid
(8) Control sleeve
(12) Cam disk
(14) Plunger spring
(15) Delivery valve
(16) Gear Cam disk (12) is driven from the engine by gear (16). Cam disk (12) is attached to plunger (11) that has dual motion. The lobes on cam disk (12) cause the plunger to reciprocate. The reciprocating motion pressurizes the fuel. This reciprocating motion brings the fuel into the fuel injection pump. Plunger (11) rotates with cam disk (12). This aligns the discharge grooves with each one of the four injection ports on the body of the fuel injection pump. The grooves are aligned in a successive order with the injection ports.The lobes of the cam determine