ILRB-3000 GEA20261
RAS and RAS-J WHISPAIR Blowers
Page 24 of 33
F - Performing the Final Assembly
1. Install all of the bearings, making sure they are tight against the respective shaft shoulders. Work on the gear end bearings
first and press them into place using a suitable length of tubing in contact only with the inner races. The impellers will be driven
against the opposite headplate. Remove the shims (17) from behind both drive end bearing carrier flanges and press the
bearings at this end into place against the shaft shoulders.
On a belt-drive unit with an extended shaft, use the spacer sleeve (62) to push the inboard bearing (60) into its final position.
There is no shaft shoulder behind this bearing, but there is a stop for the sleeve. Make sure that the inner race flange of bearing
(60) is facing outboard.
2. Install the bearing lockwasher (25) and locknuts (24) on each shaft and tighten the nuts with a spanner wrench. Lock the nuts
by bending a tab on each washer into a slot in the nut.
3. Install new or original gears and set the impellers as described in Operation B.
4. Place the bearing clamp plate (8) over the main bearing (31) and tighten all of the screws. For an extended type drive shaft,
the end cover (58) serves as the clamp plate but cannot be installed until later.
5. Using 1/2-inch (13mm) feeler gauges, determine the maximum clearance between the outer race and one of the rollers near
the top for each of the drive end bearings (31). Obtain pieces of brass shim stock that are as thick as the clearances measured,
about ¾ inches (19mm) wide, and long enough to reach completely through the bearings. Push one piece through each
bearing, in the spaces between rollers, then rotate that shaft so that one roller of each row is up on the shim stock. This
removes all clearances, and forces the bearing rollers and races to center as in normal running. Refer to Figure 15.
6. Set the impellers lengthwise in the case using long pieces of shim stock, or feelers, as wedges between the two ends of each
impeller and the headplates. Apply the total end clearance obtained in Step 8 of Operation D to the two ends of each impeller
and the headplates. Place wedges equal to two-thirds of the total end clearance obtained in Step 8 of Operation D at the gear
end and one-third of the total at the drive or thrust end. Bump the shafts to obtain the required impeller positions. Set the drive
end clearance first, after installing an tightening drive shaft end cover (58) if used.
7. With feeler gauges, carefully measure the spaces between the drive end bearing carrier flanges and the headplate face.
Insert shims (17) of the correct thickness to fill these spaces. The original shims should be correct if the bearings and carriers
were returned to the original location.
8. Remove the wedges from the ends of the impellers inside the casing.
9. Tighten all of the bearing carrier flange screws.
10. Recheck the impeller end clearances for proper values (as noted in the tables), then remove the brass shim stock from both
bearings (31).
11. Check the front and back clearances of the impeller lobes as outlined in Operation C, and reset the timing if not correct.
12. Reassemble the unit, starting by installing the main end cover (5) and proceeding in reverse order through Operation A from
Step 5. Be careful with the lip seal (23) or new O-ring (59) in the end cover (5).
13. Check the work area to make sure no parts have been left out in assembly.
14. Turn the drive shaft over several times by hand as a final check for impeller contact or case rubs.
15. Reinstall the coupling or belt sheave. Check the alignment with the driver and reconnect all external piping.
16. Start and operate the unit for a reasonable period in the manner outlined for initial starting under OPERATION.
ILRB-3000 GEA20261 RAS and RAS-J WHISPAIR Blowers.pdf 24
03/09/2015 13:21:27
Summary of Contents for Roots RAS Whispair
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