Single Bearing Machines
Alignment of single bearing a.c. generators is critical. If necessary, shims should be fitted under the feet to counteract
any irregularities in the mounting surfaces.
If there is any doubt about the alignment, the covers at the none-drive end should be removed and the air gap checked
with long feeler gauges to ensure uniformity around the periphery of the rotor.
Assembly to Engines
The sequence of assembly to the engines should generally be as follows:-
1.
Check on engine distance from the flywheel/coupling mating face to engine flywheel housing face. This should be
within ± 0.5 mm of nominal dimension. This is necessary to ensure that the a.c. generator bearing does not thrust
against the bearing caps.
2.
Check that the bolts securing the flexible plates to the shaft hub are tight and locked into position.
Torque tightening is as follows:-
PC1
Bolt size M10. Torque tighten to 5.7 kgf-m (56N-m) (41lbf-ft)
SC1
Bolt size M12. Torque tighten to 10 kgf-m (98N-m) (721bf-ft)
SC2/3
Bolt size M16. Torque tighten to 25 kgf-m (244N-m) (1801bf-ft)
3.
Remove drive end a.c. generator covers for access to coupling and adaptor bolts.
4.
Check that coupling discs are central with adaptor spigot. This can be adjusted by the tapered wooden wedges
supplied between the fan and adaptor for transit reasons; Alternatively the rotor can be suspended by means of a
rope sling through the adaptor opening.
5.
Offer the a.c. generator to engine and engage both flexible plates and housing spigots at the same time, finally
pulling home by using the housing and coupling bolts.
6.
Tighten coupling to flywheel bolts.
7.
Remove wooden wedges and replace covers.
8.
Run the machine up to speed and check for excessive vibration.
CAUTION NOTE:
When dismantling a.c. generator from the engine, care should be taken to ensure that the
rotor is positioned with a pole at the bottom center line. This is to avoid any damage to the
bearing or exciter by limiting the rotor movement to that of the air-gap.
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