HEAD 9J8808 - Caterpillar

The governor transfers the requirements of the operator to the fuel injector rack control linkage. The governor maintains the desired engine speed by the position of the throttle. The governor output shaft moves immediately when the throttle is moved. The movement of the governor output shaft then causes the fuel injector rack control linkage to rotate. The rotation of the fuel injector rack control linkage causes the fuel injector rack to move. As the rack moves to change the engine speed, the governor adjusts the amount of fuel that is delivered to the cylinders. This causes the engine to stabilize at the speed that corresponds to the throttle position.
Illustration 1 g00520141
Typical governor (A) Pin (B) Shims (1) Governor drive gear (2) Shaft (3) Flyweight carrier (4) Flyweights (5) Riser (6) Low idle spring (7) High idle spring (8) ShaftThe governor senses engine speed from the camshaft through governor drive gear (1). Shaft (2) connects governor drive gear (1) to flyweight carrier (3). As flyweights (4) rotate, a centrifugal force is created. This force is converted to linear motion, moving riser (5) toward low idle spring (6) and high idle spring (7) when the engine speed increases. At the low idle speed, low idle spring (6) exerts an opposite force on riser (5). At higher engine speeds, high idle spring (7) also becomes compressed. When the engine speed decreases, springs (6) and (7) move riser (5) toward flyweights (4). Thus, there is a unique riser position for every engine speed. Because the riser has a unique position for every engine speed, this is a full range rpm governor. The riser position provides the speed position for the rest of the governor.Note: Pin (A), which is located on riser lever (18) engages in riser (5).
Illustration 2 g00520177
Governor Schematic (A) Pin (C) FUEL ON output to fuel rack (D) FUEL ON input from operator (E) Speed increase input from engine (9) Governor output shaft (10) Limit lever setscrew (11) Control lever (12) Fulcrum lever (13) Pivot lever (14) Limit lever (15) Torque cam lever (16) Torque cam (17) Pivot shaft