The bearing(s) are a press fit and can be removed from the
shaft with 3 leg or 2 leg manual or hydraulic bearing pullers.
SINGLE BEARING ONLY : Before trying to pull off the
bearing remove the small circlip retaining it.
When fitting new bearings use a bearing heater to expand the
bearing before fitting to the shaft. Tap the bearing into place
ensuring that it contacts the shoulder on the shaft.
Refit the retaining circlip on single bearing generators.
1. Remove exciter leads X+, XX- at the AVR.
2. Slacken 4 bolts (2 each side) situated on horizontal
centre line holding the terminal box.
3. Remove 2 bolts holding lifting lug, at the non-drive end,
and remove lug.
4. Remove sheet metal cylindrical cover (4 screws) over
PMG (if fitted) or Remove shallow sheet metal cover (4
screws) at the nondrive end.
5. Ease up the terminal box and support clear of the
nondrive endbracket.
6. Remove 6 bolts holding the non-drive endbracket to the
stator bar assembly. The endbracket is now ready for
removal.
7. Replace the lifting lug onto the endbracket and sling the
endbracket on a hoist to facilitate lifting.
8. Tap the endbracket around its perimeter to release from
the generator. The endbracket and exciter stator will
come away as a single assembly.
9. Remove the 4 screws holding the exciter stator to the
endbracket and gently tap the exciter stator to release it.
Replacement is a reversal of the above procedure.
Remove the permanent magnet generator. Refer to 7.5.3.1
or
Remove the four screws holding the sheet metal cover at the
non drive end and remove cover.
With the PMG rotor removed single
bearing generator rotors are free to move
in the frame. Ensure frame is kept in the
horizontal plane when lifting.
1. Remove 2 screws holding the sheet metal cover around
the adaptor at the drive end and remove the cover.
2. Remove the bolts holding t he adaptor to the endbr acket
at the drive end.
3. T ap off the adaptor. It may be preferred to sling the
adaptor first depending on its size and weight.
4. Remove the screens and louvres (if fitted) at each side
on the drive end.
Now ensure that the rotor is positioned with a full pole face at
the bottom centre line. This is to avoid damage to the bearing
exciter, or rotor winding, by limiting the possible rotor
downward movement to the air gap length.
5. Remove 6 bolts holding drive endbracket onto adaptor
ring DE. The boltheads face towards the non-drive end.
The top bolt passes through the centre of the lifting lug.
6. Tap the drive endbracket away from the adaptor ring DE
and withdraw the endbracket.
7. Ensure the rotor is supported at the drive end on a sling.
8. Tap the rotor from the non-drive end to push the bearing
clear of the endbracket and its position within an 'O' ring.
1. Remove the screws, screens and louvres (if fitted) at
each side on drive end adaptor.
2. UC I224, UCI274, UCM224, UCM274, UCD274 Only
Remove 6 bolts holding the adaptor at the drive end. It
may be preferred to sling the adaptor on a hoist. The bolt
heads face towards the non-drive end. The top bolt
passes through the centre of the lifting lug.
2a. UCD224 Only Remove 6 bolts holding the adaptor at the
drive end. It may be preferred to sling the adaptor on a hoist.
3. UC I224, UCI274, UCM224, UCM274, UCD 274 Only Tap
the adaptor away from stator bar adaptor ring.
3a. UCD224 Only Tap the adaptor away from stator bar
assembly.
4. Ensure the rotor is supported at drive end on a sling.
5. Tap the rotor from the non-drive end to push the bearing
clear of the endbracket and its position within an 'O' ring.
6. Continue to push the rotor out of the stator bore,
gradually working the sling along the rotor as it is
withdrawn, to ensure that it is fully supported at all times.
Replacement of rotor assemblies is a reversal of the
procedures above.
Before commencing re-assembly, components should be
checked for damage and bearing(s) examined for loss of
grease.
Fitting of new bearing(s) is recommended during major
overhaul.
Before replacement of a single bearing rotor assembly, check
that the drive discs are not damaged, cracked or showing
other signs of fatigue. Also check that the holes in the discs
for drive fixing screws are not elongated.
Caution !