COVER 1722873 - Caterpillar

Illustration 1 g00521722
Fuel Transfer Pump (A) Flow (1) Screen (if equipped) (2) Inlet check valve (3) Spring (4) Piston assembly (5) Outlet check valve (6) Piston check valve (7) Tappet assembly (8) Cam (9) PassageThe fuel transfer pump is located in the front housing of the governor. The pump is activated by cam (8) that is attached to the shaft of the governor drive gear. Piston assembly (4) and tappet assembly (7) are stroked up and down by cam (8) and spring (3) .Fuel enters the fuel transfer pump through screen (1) and inlet check valve (2). On the upstroke of piston assembly (4), inlet check valve (2) closes. Outlet check valve (5) closes in order to prevent fuel from being pulled back in the pump from the outlet. As pressure increases above piston assembly (4), piston check valve (6) opens in order to allow fuel to fill passage (9) .On the downstroke, increasing fuel pressure in passage (9) causes piston check valve (6) to close. The pressurized fuel pushes outlet check valve (5) open. The fuel then flows through the main fuel filter and to the engine. Inlet check valve (2) opens in order to allow fuel to fill the cavity above piston assembly (4) .During engine shutdown, the check valves are held closed by springs.