Single Bearing MachinesAlignment of single bearing a.c. generators is critical. If necessary, shims should be fitted under the feet to counteractany 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 checkedwith long feeler gauges to ensure uniformity around the periphery of the rotor.Assembly to EnginesThe 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 bewithin ± 0.5 mm of nominal dimension. This is necessary to ensure that the a.c. generator bearing does not thrustagainst 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:-PC1Bolt size M10. Torque tighten to 5.7 kgf-m (56N-m) (41lbf-ft)SC1Bolt size M12. Torque tighten to 10 kgf-m (98N-m) (721bf-ft)SC2/3Bolt 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 wedgessupplied between the fan and adaptor for transit reasons; Alternatively the rotor can be suspended by means of arope 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, finallypulling 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 therotor is positioned with a pole at the bottom center line. This is to avoid any damage to thebearing or exciter by limiting the rotor movement to that of the air-gap.5
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