Flexible-Type Couplings — Flywheel Housing-Mounted Driven Equipment

1. Droop

Mount a dial indicator on the engine flywheel housing. Mark the engine flywheel housing. Mark the flywheel at points A, B, C, and D in 90° incre- ments as shown in Figure 32. The indicator tip must contact the pilot diameter of the flywheel assembly. With the dial indicator in position (A), set the reading to zero. Place a pry bar under the flywheel assembly at position (C) and, by prying against a floor mounted support, raise the fly- wheel until it is stopped by the main bearings. (Caution: Do not pry against the flywheel housing.) Record the reading of the dial indicator. This is the amount of droop in the crankshaft,

which results from engine bearing clearances and natural droop as a result of the overhung weight of the flywheel. The flywheel should be raised several times to get a “feel” for the bearing clearance to prevent excessive lift which means reverse bending of the crankshaft.

Figure 32

2. Flywheel Concentricity

Remove the pry bar and check to ensure that the dial indicator has returned to zero. If not, reset. Rotate the crankshaft, in the normal direction only, and record the Total Indicator Reading (TIR) when the flywheel positions (A), (B), (C), and (D) are at the top. (Refer to Page 58 for proper tolerances.)

3. Crankshaft End Play

Ensure the crankshaft-flywheel assembly is completely to the rear- most position of the engine assem- bly. Reset the dial indicator to zero. Relocate the pry bar and move crankshaft-flywheel assembly for- ward in the engine assembly. The dial indicator reading in this position is the crankshaft end play.

4. Flywheel Face Run Out

Set the tip of the indicator on the face of the flywheel Figure 33. Position the crankshaft to the front of its end play and zero the indicator. Shift the crank- shaft to the rear of its end play, and record the TIR. With the crankshaft to the rear of its end play, zero the indicator. Rotate the crankshaft and record the TIR when the flywheel positions (A), (B), (C), and (D) are at the top. Be sure to remove the crank- shaft end play before recording these readings. Remove the flywheel hous- ing access cover and place a pry bar between the rear face of the flywheel housing and the front face of the fly- wheel assembly. Move the crankshaft- flywheel assembly to the rear of the engine to remove all end play.

Figure 33

5. Flywheel Housing Concentricity Mount the dial indicator on the fly- wheel assembly with the tip located on the pilot bore of the flywheel hous- ing and set the reading to zero. Rotate the crankshaft in the direction of normal engine rotation and record

the indicator readings at positions (A), (B), (C), and (D). Subtract the droop dimension (Step 1) from the reading indicated at position (C) and subtract one-half the droop dimension from the reading indicated at positions (B) and (D) on the flywheel housing to determine the true concentricity.

Figure 34

6. Engine Mounting Face Depth With the crankshaft-flywheel assem- bly moved to the frontmost position, place a straight edge across the mounting face of the flywheel hous- ing, from position (A) to (C). With a scale measure the distance from the rear face of the flywheel housing to the coupling mounting face of the flywheel as shown in Figure 34. Repeat the same measurement with the straight edge located on positions (B) and (D).

Steps 1 through 6 establish the engine tolerances. The following Steps, 7 and 8, determine the driven equipment

tolerances or refer to manufacturers specifications.

7. Support the driven equipment input shaft until it is centered (all droop is removed).

8. Driven Equipment Mounting Face Depth

With the driven equipment mounting and driving flange or face centered, as described in Step 7, and the flex- ible coupling attached to the input shaft, the face depth can be mea- sured. Place a straight edge across the surface of the front face of the coupling which mates to the flywheel assembly. With a scale measure the distance from the coupling mounting face to the mounting face of the dri- ven equipment housing as shown in Figure 35.

This dimension must equal the engine mounting face depth Step 6 less one- half of the crankshaft end play as described in Step 4. If not, it must be corrected by changing the adapting parts, or by shimming if the required correction is small. Shimming is usu- ally the less desirable approach. With the engine and driven equip- ment tolerances known, proceed to mount the driven equipment to the engine.

9. Support the driven machine on a hoist and bring it into position with the engine. 10. Align the driven equipment housing mounting flange with the flywheel housing, using locating dowels if required. Install connecting bolts with sufficient torque to compress the lockwashers, but not to final torque.

11. Install the bolts which secure the cou- pling to the flywheel and torque as recommended.

12. Check crankshaft end play to ensure that the proper relationship exists between the engine mounting face depth Step 6 and the driven equip- ment mounting face depth Step 8. Place a pry bar between the flywheel assembly and the flywheel housing. The crankshaft should move both for- ward and backward within the engine and, in both positions, remain fixed when pressure on the pry bar is relaxed. Any tendency of the crank- shaft to move when pry bar pressure is released indicates that the driven equipment and coupling assembly are imposing a horizontal force on the crankshaft, which will result in thrust bearing failure. If this condition exists, readjust the thickness of shims used between the driven equipment input shaft and the coupling as described in Step 8.

13. Determine quantity and thickness of shims required between the driven equipment mounting pads and the base assembly; locate the shim packs and install driven equipment mounting bolts to the base assembly. NOTE: Always use metal shims. Tighten the bolts to one-half the torque recommendation.

14. Loosen the bolts holding the driven equipment housing to the flywheel housing until the lockwashers move freely. Using a feeler gauge, check the clearance between the two housings to determine if the driven equipment is properly shimmed. Measurement should be made in four 90° incre- ments in the vertical and horizontal planes. If the feeler gauge indicates any area where the clearance varies by more than 0.005 in (0.13 mm),

readjust the driven equipment hous- ing position by changing the shims. There must be clearance at all points when making this check.

15. With the proper number of shims installed to align the driven equip- ment housing parallel to the flywheel housing, tighten the bolts securing the driven equipment housing to the flywheel housing sufficiently to com- press the lockwashers.

16. Torque the bolts holding the driven equipment frame to the base assembly to one-half the recommended value. 17. Repeat Step 14. If the feeler gauge

measurements indicate that misalign- ment is still present, repeat operation described in Steps 14 through 17 until proper alignment is obtained. 18. Retorque all coupling and mounting