G3408 and G3412 Engines Caterpillar

Adjusting The High Idle Stop

1. Start the engine and allow the engine to run until the coolant temperature is normal.

2. Loosen locknut (1). Turn stop screw (2) counterclockwise for approximately two turns.

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NOTICE
With the stop screw in this position, the engine can overspeed. This can cause damage to the engine components. Be ready to shutdown the engine if it has an overspeed condition.

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Illustration 1	g00597436

3. Use the adjustment screw (3) in order to adjust the engine to the correct speed. On PSG governors that have electric speed control, adjust the speed with the electric motor.

4. Turn stop screw (2) clockwise. Tighten locknut (1).

5. If the engine speed is still correct, the adjustment is correct.

Speed Droop

This engine has adjustable speed droop. The adjustable speed droop is between zero and seven percent. This amount will be different for different applications. This percent of adjustable speed droop is the percent between the engine speed at no load and the engine speed at full load. In order to calculate the adjustable speed droop, use the following formula:

Illustration 2	g00600477

1. Find the desired adjustable speed droop for the application.

2. Multiply the full load speed by the desired adjustable speed droop. Add the number from this multiplication to the full load speed. This will calculate the speed at no load.

3. Start the engine and allow the engine to run until the temperature of the coolant is normal.

4. Adjust the engine speed to no load.

5. Connect a known load to the engine. The load must be less than the full capacity of the engine. Make a record of the decrease in engine speed.

6. Determine the ratio between the load that is on the engine, and the full load capacity of the engine. This ratio must be equal to the ratio of the decrease in engine speed. This decrease in engine speed is described in the following equation.

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Illustration 3	g00600486

7. If the ratios are not equal, an adjustment will be necessary. Remove the load and stop the engine. If the engine speed has decreased too much, the adjustable speed droop must be decreased. If the decrease in engine speed is not enough increase the amount of speed droop. Refer to the section on Adjustable Speed Droop.

Adjustable Speed Droop

1. Make a mark on the cover in order to show the original position of bracket (2). This will show the amount that the bracket will move from this position.

2. Loosen screw (3). This screw holds bracket (2) and lever (1) in the correct position.

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Illustration 4	g00580093
Nonelectric Governor (1) Stop Screw. (2) Screw. (3) Bracket. (4) Lever.

3. In order to increase the adjustable speed droop, turn the lever (1) in the counterclockwise direction. In order to decrease the adjustable speed droop, turn the lever (1) in the clockwise direction.

   Note: The engine will begin to hunt when the engine is placed under certain conditions. If the lever is turned too far in the clockwise direction, the engine will hunt.

4. Tighten screw (3) in order to hold the lever and the bracket in position. The adjustable speed droop should be checked after an adjustment is made. Several adjustments may be necessary in order to achieve the desired setting.

5. When lever (1) is in the position that gives the desired speed droop, set the stop screw (4) against the lever (1). The lever will return to the desired position after disassembly and assembly of the governor.