CONSOLE GP-OPERATOR 3175539 - Caterpillar

continue until upper port (19) is uncovered by helix (17) on the plunger. At this instant, effective stroke ends and this high pressure fuel will spill through upper port (19) into the gallery. This will allow spring (20) to close check (21), which will end the injection cycle.The downward motion of the plunger will continue until lifter (13) reaches the nose of the camshaft. The plunger will be returned upward by tappet spring (4). This will allow the cavity under the plunger to be refilled from the fuel in the gallery. The unit injector is now ready for the next cycle.In addition to vertical motion, the plunger can rotate with respect to barrel (9) by gear (15). The gear slides in order to allow vertical movement of the plunger and the gear meshes with rack (7). The rotation of the gear changes the relationship between helix (17) and upper port (19). The amount of fuel that is injected into each combustion chamber then changes. for example, If rack (7) is moved to the right, then plunger (6) will rotate CCW. (This movement is viewed from the top.) The distance between the bottom end of the plunger and helix (17) then increases with respect to upper port (19). The effective stroke is increased and more fuel is injected into the combustion chamber.Control Linkage for the Fuel Injection Rack
Illustration 10 g00859254
Unit injectors and rack control linkage (1) Lever (2) Torsion spring (3) Shaft (4) Rack (5) Synchronization screw (6) Clamp (7) Clamp assembly (8) Fuel setting screw (9) Link (10) Lever assembly (11) Unit injector
Illustration 11 g00859641
Unit injector and rack control linkage (1) Lever (A) FUEL ON (B) FUEL OFF (3) Shaft (4) Rack (5) Synchronization screw (6) Clamp (11) Unit injectorThe rack control linkage connects the governor output to unit injector (11) at each cylinder. The governor output shaft is pinned to link (9). The link is connected to lever assembly (10). When the governor demands more fuel,