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| Illustration 1 | g00520642 |
Governor Linkage And Fuel Ratio Control Schematic (A) Fuel ON output to rack (B) Fuel ON input from operator (1) Governor output shaft (2) Inlet port (3) Fuel ratio control (FRC) (4) Retainer shaft (5) FRC lever (6) Control lever (7) Limit lever (8) FRC lever setscrew (9) Limit lever setscrew (10) Fulcrum lever (11) Pivot lever (12) Pivot shaft (13) Torque cam lever (14) Torque cam (15) Riser lever | |
The governor limits the fuel that is injected into the combustion chamber when the rated load or a lug condition is reached. When this condition occurs, limit lever (7) is against limit lever setscrew (9) and Governor output shaft (1) is in the maximum FUEL ON position. Torque cam lever (13) has rotated about a pin on limit lever (7) until torque cam lever (13) contacts torque cam (14). If the load to the engine is increased in this condition, engine speed will decrease. This decrease will be felt by the flyweights, causing the riser to rotate riser lever (15) and pivot shaft (12) to a new position. Since torque cam (14) is fixed to pivot shaft (12), different torque characteristics can be achieved by changing the profile on torque cam (14) .
The fuel ratio control (FRC) limits the fuel by preventing limit lever (7) from reaching limit lever setscrew (9). This is accomplished with FRC lever (5). As boost increases, limit lever (7) is allowed to rotate further toward limit lever setscrew (9). At full boost, limit lever (7) will not be restricted by fuel ratio control (3) .
In order to deliver more fuel to the engine at start-up, some governors contain a notch in torque cam (14). When the engine is not operating, the position of the torque cam allows torque cam lever (13) to enter the notch. This allows the rack to advance beyond the FRC limit. Once the engine is started the torque cam rotates and the torque cam lever is forced out of the notch. The rack is then limited by the FRC. This feature is known as deep notch and it provides overfueling for easier starting.