3500 Industrial Engines Caterpillar

Incorrect compensation adjustments can result from the following conditions: high overspeeds after load changes, low speeds after load changes and slow return to normal speed. The governor may appear to be operating normally at no load.

After the temperature of the engine and the oil in the governor have reached normal operating values, make adjustments with the engine running at no load conditions.

Illustration 1	g00868768
UG8 lever type governor (typical example) (1) Compensation pointer (2) Nut (3) Plug

1. Loosen nut (2) that holds compensation pointer (1). Rotate the pointer to the uppermost position. Tighten nut (2).

2. Remove plug (3) from the base of the governor in order to get access to the needle valve.

3. Use a screwdriver in order to turn the needle valve. Turn the needle valve in a counterclockwise direction to the open position. Ensure that the screwdriver engages with the shallow slot of the compensation needle valve. Be sure that the screwdriver does not engage in the deep slot that is at a right angle to the shallow slot.

4. Allow the engine to surge for approximately 30 seconds in order to help remove air from the governor oil passages.

5. Loosen nut (2) that holds compensation pointer (1). Rotate compensation pointer (1) to the original position. Tighten nut (2).

6. Determine the number of turns that are required in order to open the needle valve. Close the valve completely and make a note of the number of turns needed in order to close the valve.

7. Turn the needle valve in a clockwise direction until the engine's speed surge stops.

8. When the engine's speed surge stops, open the needle valve.

   Note: If the following conditions are met, then governor adjustment is correct. There is no engine's speed surge. The needle valve is 1/2 to 3/4 of a turn toward the open position.

9. Move the governor linkage in order to change the engine speed. Install plug (3) in the base. If the needle valve is more than 3/4 of a turn open, proceed with the following steps.

10. Loosen nut (2). Move compensation pointer (1) up two marks on the pointer scale.

11. Turn the needle valve in a counterclockwise direction. Rotate 3 to 5 turns.

12. Allow the engine to surge for approximately 30 seconds in order to help remove air from the governor oil passages.

13. Turn the needle valve in a clockwise direction until the engine's speed surge stops.

14. Determine the number of turns that are required in order to open the needle valve. Close the valve completely and make a note of the number of turns needed in order to close the valve.

15. Turn the needle valve to the previous position. Refer to Step 13.

16. Move the governor linkage in order to change the engine speed.

    Note: If the following conditions are met, then governor adjustment is correct. There is no speed surge. The needle valve is 1/2 to 3/4 of a turn toward the open position. If the needle valve is more than 3/4 of a turn open, repeat Steps 10 through 16.

    Note: A needle valve that is opened less than 1/2 turn will cause a slow return of the engine to normal speed after a load change. If the compensation pointer is too far toward the maximum position, the engine speed change will be too great when the load changes.

17. Install plug (3) in the base.

Low Idle And High Idle Speed Adjustment

Connect a tachometer with good accuracy to the engine. Refer to Testing and Adjusting, "Engine Speed Measurement".

1. Start the engine and run the engine in order to get the engine to the normal operating temperature.
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   Illustration 2	g00868772
   Low and high idle adjustment (typical example) (1) Low idle adjustment screw (2) Locknut (3) Locknut (4) High idle adjustment screw (5) Governor speed adjusting shaft

2. Move governor speed adjusting shaft (5) in order to run the engine at high idle speed. Loosen locknut (3) and turn high idle adjustment screw (4). Turn adjustment screw (4) clockwise in order to decrease engine speed. Turn the adjustment screw counterclockwise in order to increase engine speed.
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   Illustration 3	g00868775
   Low and high idle stop lever (typical example) (6) Low and high idle stop lever

3. After the high idle speed has been adjusted, tighten the locknut and check high idle speed again.

4. Move governor speed adjusting shaft (5) in order to run the engine at low idle speed. Loosen locknut (2) and turn low idle adjustment screw (1). Turn adjustment screw (1) clockwise in order to increase low idle speed. Turn the adjustment screw counterclockwise in order to decrease low idle speed.

Adjustment For The Speed Droop

Adjustment For Zero Droop

1. Disconnect the pressure lines for the engine oil and for the air inlet in the fuel ratio control housing.
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   Illustration 4	g00868776
   Cover and shutoff solenoid (typical example) (1) Cover assembly

2. Remove the oil level gauge from cover assembly (1).

3. Remove the screws that hold cover assembly (1) in position. Remove cover assembly (1) and the shutoff actuator as a unit from the governor.
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   Illustration 5	g00868777
   Oil pressure line to fuel ratio control (typical example) (2) Junction block (3) Oil pressure line

4. Remove the screw and pull junction block (2) from oil pressure line (3).
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   Illustration 6	g00868779
   Removal of fuel ratio control (3) Oil pressure line (4) Fuel ratio control housing (5) Lever (6) Governor shutoff strap

5. Remove the eight bolts that hold fuel ratio control housing (4) to the governor housing. Lift the unit until lever (5) is disconnected from the compensation lever. Rotate the unit. Lift the unit in order to move the fuel ratio control around governor shutoff strap (6). Do not damage pressure line (3) when the fuel ratio control is removed.
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   Illustration 7	g00868781
   Governor shutoff strap (6) Governor shutoff strap (typical example)

6. Lift governor shutoff strap (6) from the pins that are in the governor housing. Remove governor shutoff strap (6).
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   Illustration 8	g00868784
   Droop adjustment (7) Speeder plug (8) Droop cam (9) Screw (10) Bracket (11) Terminal shaft

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   Illustration 9	g00868786
   Droop adjustment (10) Bracket

7. Install the 3S-3269 Indicator Contact Point on the dial indicator. Put the dial indicator in position on the governor with the contact point on bracket (10) of speeder plug (7). Adjust the dial of the indicator to zero.

8. Move terminal shaft (11) from the maximum position to the minimum position. The dial indicator must read 0.00 to 0.05 mm (0.000 to 0.002 inch).

9. If the adjustment for the speed droop is incorrect, loosen screw (9). Move droop cam (8). Tighten screw (9). Move droop cam (8) toward speeder plug (7) in order to increase droop. Move droop cam (8) away from speeder plug (7) in order to decrease droop.

10. Check the adjustment of the speed droop.

11. Install governor shutoff strap (6) in the governor.
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    Illustration 10	g00868787
    Governor assembly (typical example) (12) Compensation lever

12. Install the fuel ratio control over governor shutoff strap (6). Ensure that lever (5) is engaged correctly with compensation lever (12). Install the screws in order to hold the unit to the governor.

13. Ensure that the O-ring seals are installed on the oil pressure line and into the fuel ratio control. Install junction block (13).
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    Illustration 11	g00868792
    Fuel ratio control oil line (13) Junction block

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    Illustration 12	g00868793
    Governor cover assembly (typical example) (14) Oil level gauge (15) Cover assembly

14. Install the shutoff actuator and cover assembly (15) on the fuel ratio control housing. Install oil level gauge (14) in the cover assembly.

15. Connect the engine oil pressure line and the air inlet pressure lines to the fuel ratio control housing.

Adjustment For Positive Droop

1. Remove the fuel ratio control from the governor. Refer to Steps 1 through 6 in the "Adjustment For Zero Droop"section.

2. Connect a tachometer with good accuracy to the engine. Refer to Testing and Adjusting, "Engine Speed Measurement".

   Note: Dimension (A) is an approximate dimension. Make final adjustments with the engine running.

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   Illustration 13	g00868982
   Speed droop assembly (typical example) (8) Droop cam (9) Screw (16) Droop lever (A) Speed droop setting

3. Loosen screw (9). Move droop cam (8) on droop lever (16) in order to get the correct distance for the droop percentage. Refer to Table 1 in order to get the correct dimension.
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   Table 1

   Speed Droop Chart
   Droop Percentage	Distance A
   3	8.33 mm (0.330 inch)
   5	6.76 mm (0.270 inch)
   10	3.58 mm (0.140 inch)

4. Install the fuel ratio control on the governor. Refer to "Adjustment For Zero Droop". Follow Steps 12 through 15. Start the engine and run the engine in order to get the engine to the normal operating temperature.

5. Put a load on the engine in order to get the maximum full load. Make a note of the full load rpm.

6. Remove all load from the engine. Make a note of the no load high idle rpm.

7. Find the difference between the no load high idle rpm and the full load rpm. Divide the difference by the full load rpm and multiply that total times 100. The result is the percent of speed droop. Use the following formula to determine the percent of droop.

   No load high idle speed − full load rpm × 100 = % of full load rpm speed droop.

8. If the speed droop is not correct, stop the engine and move droop cam (8) toward speeder plug (7) in order to increase speed droop. Move droop cam (8) away from speeder plug (7) in order to decrease speed droop.

9. Repeat Steps 1 through 8 in order to check the speed droop. If necessary, adjust speed droop again.

Fuel Ratio Control

The UG8 lever type governors are equipped with a fuel ratio control. Adjustments are generally made at the factory. Adjustments to rebuilt governors are made when a test bench is available. The following adjustment can be used in order to control acceleration smoke and engine response.

Note: The engine must be shutdown before making this adjustment in order to keep dirt and foreign material out of the governor.

1. Remove the cover assembly and the shutoff actuator from the top of the governor.

2. Turn adjusting screw (1) clockwise in order to reduce smoke. Turn counterclockwise in order to increase engine response.

3. Turn adjusting screw (1) clockwise or counterclockwise, only 1/2 turn or less.

4. Replace the top cover assembly and the shutoff actuator on the governor.

5. Start the engine. Check the acceleration smoke and the engine response in order to determine if an adjustment is necessary. Repeat Steps 1 through 3 if an adjustment is necessary.

Illustration 14	g00868983
Location of adjustment screw (1) Adjustment screw