RETAINER AS 1330699 - Caterpillar

When the plunger is at the top of the effective stroke, fuel flows from the fuel supply chamber. Then, the fuel flows around the fuel injector. Next, the fuel flows through the lower port and the upper port of the barrel. As the plunger is moved downward by the rocker arm, fuel is pushed back into the supply chamber through the lower port. Now, the fuel can flow upward through a passage in the center of the plunger. Then, the fuel flows outward through the upper port of the barrel. As the lower port is closed by the lower scroll on the plunger, fuel can still flow through the upper port. Fuel will continue to flow through the upper port until the upper port is closed by the upper scroll on the plunger. At this point, fuel injection starts and the effective stroke begins. During the effective stroke, fuel is injected into the cylinder until the downward movement of the plunger causes the lower scroll to open the lower port. When the lower port is opened, the fuel pressure is released.The fuel then flows through the center passage of the plunger. During the remainder of the downstroke, the fuel flows through the lower port. This sudden release of pressure causes the fuel to hit the deflector (spill) with a high force. The deflector (spill) protects the housing nut of the fuel injector from erosion (wear) due to the force of the released fuel. During the return stroke (upstroke), the chamber inside the injector barrel is filled with fuel again.The plunger can be turned by the rack while the plunger is being moved up and down by the rocker arm. The rack is engaged with the gear on the plunger. When the rack moves, the rack turns the plunger through the gear. The rotation of the plunger controls fuel injection timing and the fuel output of the fuel injector. The rotation of the plunger changes the relationship between the scrolls on the plunger and the ports in the barrel.By changing this relationship, the length of the effective stroke can be increased or the length of the effective stroke can be decreased. Also, the timing of the fuel injection is changed.When the rack is moved all the way inward against the fuel injector body, no fuel injection takes place during the downstroke of the plunger. This is the FUEL-OFF position. A small amount of outward rack movement is used as a movement of no fuel or OFF position for governing purposes. The distance of no fuel starts at the ALL THE WAY INWARD position of the rack. The distance of no fuel ends when the lower scroll opens the lower port and the upper scroll closes the upper port. Fuel rack movement in the fuel-on direction produces an interval in the plunger stroke when both ports are closed by the scrolls and fuel injection takes place. As the rack is moved farther in the fuel-on direction, the quantity of fuel