Alignment Procedure for Certain G3500 Generator Set Engines with Gearbox {7002} Caterpillar

Engine

G3516H (S/N: NWJ1-UP; GLN1-UP)

G3520C (S/N: LGS177-UP)

G3520H (S/N: GFR1-UP)

Introduction

This Special Instruction provides the procedure to align the engine to the gearbox and the gearbox to the generator. Proper alignment of the engine to the gearbox and the gearbox to the generator is necessary for maximum performance and durability of the generator set.

Misalignment between the driving and the driven equipment can be detected by measuring the face and the bore misalignment. Refer to Illustration 1.

Required Tools

Types of Misalignment

Illustration 1	g03124999
Misalignment (A) Face alignment (B) Bore alignment (1) Face Gap (top) (2) Diameter Gap (top) (3) Face or angular misalignment (4) Bore or parallel misalignment (5) Face gap (bottom) (6) Diameter gap (bottom)

Parallel/Bore misalignment occurs when the centerlines of the driven equipment and the engine are parallel but not in the same plane. Refer to Illustration 2.

Illustration 2	g03131761

Initial Installation and Preparation

Note: This alignment procedure is performed with the drive line at ambient temperature.

Note: Check the alignment of the face and the bore simultaneously.

Illustration 3	g03132878
(A) Engine (B) Gearbox (C) Generator

Before making any measurements at the face or bore, ensure that all surfaces are free of grease, paint, rust, and debris. Grease, paint, rust, and other debris will affect the alignment measurements.

The gearbox input shaft should not be aligned below the engine flywheel during cold alignment due to the thermal growth of the engine, the flywheel sag and the engine main bearing clearances. The generator should be aligned above the gearbox output shaft as the thermal growth of the gearbox output shaft is greater than that of the generator. The acceptable Total Indicator Reading (TIR) range is 0 to 0.254 mm (0 to 0.01 inch) for both engine to gearbox and gearbox to generator portions of the alignment.

The engine must be bolted in place, the gearbox will be aligned to the engine, and the generator will be aligned to the gearbox. When initially coupling the gearbox to the engine, move the engine crankshaft toward the front of the engine to remove all end play.

The alignment of the gearbox to the engine is to be completed prior to aligning the generator to the gearbox. The engine is stationary during the gearbox alignment procedure. Once the gearbox is aligned and the mounting bolts are tightened, the gearbox becomes stationary and the generator is aligned to the gearbox.

Initially shim each of the gearbox and generator mounting feet 2 mm (0.079 inch). More or less shims may be required during the alignment procedure. Position the gearbox and the generator such that the mounting holes are centered with the holes in the rails or base frame. The engine to gearbox coupling will either be a black rubber coupling with an aluminum outer element or a silicone compression coupling with a steel outer element. Refer to Illustration 4 for the black rubber coupling and refer to Illustration 5 for the silicon compression coupling. The inner elements should be centered within the outer elements for both. The face of the inner element should be recessed approximately 10 mm (0.40 inch) inside the outer element for the black rubber coupling. For the silicone compression coupling the inner tooth element face should be recessed approximately 28 mm (1.10 inch) inside the outer element cover plate surface.

During the alignment of the gearbox and generator, leave the horizontal adjustment screws hand tight to minimize accidental movement during vertical adjustments. When adjusting the horizontal position of the gearbox and or generator, loosen the opposite side horizontal adjustment screws before adjusting in that direction. After all adjustments have been made, tighten all horizontal adjustment screws prior to tightening the mounting bolts. To avoid damage to the vertical adjustment screws, back the screws out prior to tightening any of the mounting bolts.

Illustration 4	g03132900
Rubber coupling to gearbox (D) Outer surface (E) Inner tooth surface

Illustration 5	g03378497
Silicone compression coupling to gearbox (D) Outer surface (E) Inner tooth surface

Illustration 6	g03378513
Generator to gearbox coupling.

The gearbox to generator coupling is the same as the previously mentioned black rubber coupling except for the adapter plate used to mate to the generator drive hub. The rubber element of this coupling should also be recessed approximately 10 mm (0.40 inch) inside the outer element.

All coupling outer elements are piloted onto either the engine flywheel or generator adapter plate to maintain alignment. All coupling inner elements are piloted onto the gearbox shafts to maintain alignment.

Dial Indicator Alignment Procedure

Note: Laser alignment is the recommended method of alignment due to the improved accuracy and repeatability of the laser.

1. Position the gearbox such that the gearbox is roughly aligned to the engine.

2. Install the gearbox mounting bolts and apply half torque.
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   Illustration 7	g03134112
   (1) Shaft surface for bore measurements (2) Hub surface for face measurements

3. Mount the dial indicators on the outer coupling element. Preload each dial indicator to a minimum of one dial rotation or 2 mm (0.079 inch). Once the correct preload is set, zero the indicators. Refer to Illustration 7.

4. Measure the bore runout readings from the gearbox input shaft and the face runout from the rear center of the gearbox hub.
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   Illustration 8	g03131676
   (A) Twelve o'clock (B) Three o'clock (C) Six o'clock (D) Nine o'clock

5. Rotate the driveline 360 degrees taking measurements at the 3 o'clock, the 6 o'clock, the 9 o'clock, and the 12 o'clock positions. The sum of (A) and (C) or (B) and (D), must not exceed 0.254 mm (0.01 inch). This value is referred to as the Total Indicator Reading (TIR). Acceptable TIR range is 0 to 0.254 mm (0 to 0.01 inch) Refer to Illustration 8.

   Note: The gearbox input shaft should be set vertically above the engine.

6. If the TIR reading is not within the correct range, loosen the gearbox mounting bolts.

7. Adjust the gearbox vertically or horizontally as needed. Once the TIR is within the acceptable range, tighten the gearbox mounting bolts to full torque.

8. Perform a soft foot check. Refer to "Soft Foot Check Procedure".

9. Once the soft foot check is complete, measure the alignment of the gear box to the engine again.

10. Position the generator such that the generator is roughly aligned to the gearbox.

11. Install the generator mounting bolts and apply half torque.
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    Illustration 9	g03134138
    (3) Surfaces for measuring the bore alignment (4) Surfaces for measuring the face alignment

12. Attach the dial indicators to the outer coupling element of the gearbox. Measure the bore runout from the gearbox output shaft or hub. Measure the face runout from either of the rear gearbox hub surfaces. Ensure that the dial indicator can make a complete revolution without contacting the gearbox pump or other components.

13. Preload each of the dial indicators to a minimum of one dial revolution or 2 mm (0.08 inch). Once the correct preload is set, zero the dial indicator.

14. Rotate the driveline 360 degrees taking measurements at the 3 o'clock, the 6 o'clock, the 9 o'clock, and the 12 o'clock positions. The sum of (A) and (C) or (B) and (D) must not exceed 0.254 mm (0.01 inch). This value is referred to as the Total Indicator Reading (TIR). Refer to Illustration 8.

    Note: The generator shaft should be set vertically above the gearbox output shaft.

15. If, the TIR is not within the acceptable range, loosen the generator mounting bolts.

16. Adjust the generator vertically or horizontally as needed. Once the TIR is within the acceptable range, tighten the gearbox mounting bolts to full torque.

17. After tightening the generator mounting bolts check the alignment again.

Laser Tool Alignment Procedure

Note: Refer to the laser alignment tool user manual instructions for additional information regarding operation of the tool.

1. Position the gearbox such that the gearbox is roughly aligned to the engine. Install the gearbox mounting bolts, tighten the bolts to half of the standard torque value.

2. Install the gearbox mounting bolts and apply half torque.

3. Mount the transducer to the outer coupling element.

4. Attach the reflector to the gearbox input shaft.

5. Connect the supplied laser alignment tool cable from the transducer to the tool.

6. Enter the required dimensions into the laser alignment tool. Examples of possible dimensions required include the following:

   • Transducer to reflector

   • Transducer to coupling centerline

   • Coupling diameter

   • RPM

   • Transducer to front feet

   • Front feet to rear feet

7. Turn the laser ON, adjust the laser beam to the center of the reflector dust cap. Once the laser beam is centered, remove the dust cap.

8. Rotate the driveline one complete revolution.

9. Record the results displayed on the laser alignment tool. Compare the readings to the following acceptable limits:

   • Vertical bore 0 to 0.254 mm (0 to 0.010 inch) Gearbox above Engine

   • Horizontal bore 0 to 0.254 mm (0 to 0.010 inch) Gearbox above Engine

   • Vertical face 0 to 0.254 mm (0 to 0.010 inch) Gearbox above Engine

   • Horizontal face 0 to 0.254 mm (0 to 0.010 inch) Gearbox above Engine

10. Adjust the gearbox as needed to maintain the correct alignment. Shims may be installed or removed in order to achieve the correct vertical alignment. Use the horizontal adjustment screws to make horizontal adjustments.

11. Once the alignment is within the specifications, torque the gearbox mounting bolts to the proper specifications.

12. Perform a soft foot check, refer to "Soft Foot Check Procedure".

13. After the soft foot check has been completed, verify that the alignment is still within the specifications.

14. Position the generator such that the generator is roughly aligned to the gearbox.

15. Install the generator mounting bolts and apply half torque.

16. Mount the transducer onto the gearbox output shaft.

17. Attach the reflector onto the outer coupling element.

18. Connect the supplied laser alignment tool cable from the transducer to the tool.

19. Enter the required dimensions into the laser alignment tool. Examples of possible dimensions required include the following:

    • Transducer to reflector

    • Transducer to coupling centerline

    • Coupling diameter

    • RPM

    • Transducer to front feet

    • Front feet to rear feet

20. Turn the laser ON, adjust the laser beam to the center of the reflector dust cap. Once the laser beam is centered, remove the dust cap.

21. Rotate the driveline one complete revolution.

22. Record the results displayed on the laser alignment tool. Compare the readings to the following acceptable limits:

    • Vertical bore 0 to 0.254 mm (0 to 0.010 inch.) Generator shaft above gearbox output shaft.

    • Horizontal bore 0 to 0.254 mm (0 to 0.010 inch) Generator shaft above gearbox output shaft.

    • Vertical face 0 to 0.254 mm (0 to 0.010 inch) Generator shaft above gearbox output shaft.

    • Horizontal face 0 to 0.254 mm (0 to 0.010 inch) Generator shaft above gearbox output shaft.

23. Adjust the generator as needed to maintain the correct alignment. Shims may be installed or removed in order to achieve the correct vertical alignment. Use the horizontal adjustment screws to make horizontal adjustments.

24. Once the alignment is within the specifications, torque the generator mounting bolts to the proper specifications.

25. Perform a soft foot check, refer to "Soft Foot Check Procedure".

26. After the soft foot check has been completed, verify that the alignment is still within the specifications.

Soft Foot Check Procedure

Note: The soft foot check can be completed with the laser alignment tool if the tool has this function.

1. Attach a dial indicator onto the main base frame near the gearbox or generator foot you plan to measure. Measure and correct any soft foot issues at the gearbox before preceding to the alignment of the generator or the soft foot check of the generator.

2. Preload the dial indicator to a minimum of one revolution or 2 mm (0.08 inch). Once the correct preload is set, zero the dial indicator.

3. Loosen the mounting bolt at the location that is being measured. Measure and record the vertical deflection of the gearbox or generator mounting foot at this location as close to the mounting bolt as possible. Only loosen one bolt at a time.

4. Maximum deflection of the gearbox or generator foot relative to the main base frame is 0.0762 mm (0.003 inch).

5. If, the indicator reading exceeds 0.0762 mm (0.003 inch), place shims under the specific generator foot mounting location you are measuring. Tighten the bolt and measure the deflection again. Once all mounting locations have been checked, tighten all bolts to the proper specification.