MarelliMotori MXB-E 225 Serie Manuel D'installation page 42


After removing the bolts from the tie rods, remove the N side shield from the casing, but be careful not
to damage the exciter windings.

Remove the 4 tie rods with nut and lock nut.

Remove the protection (310) and the screws securing the cover (455) on the D side shield (300).

Remove the D side shield.

Leave the rotor inside the casing; replace the bearings (use an appropriate extracting device to extract
them).

Carefully install the bearings on the shaft, preferably by heating them at about 80-90°C.

Remove the O-Ring (441) from the seat in the N side shield (the O-Ring must always be replaced every
time you disassemble the N side shield).

Apply a uniform layer of LGAF 3E (SKF) grease on the entire surface of the ring outside of the bearing
and on the entire surface of the seat of the bearing of the N side shield (without an O-Ring) using an
appropriate tool (brush or spatula). An excessive thickness could lead to complications during the
assembly of the shield.

Position the new O-Ring in the seat of the N side shield.

Before assembling the shield, make sure that the two guide screws are present on the lower part of the
casing.

Clean the threads of the tie-rods before using them.

Reassemble the D side shield and secure the cover (with the bearing cooled).

Partially reassemble (up to the O-Ring) the N side shield (with the bearing cooled) and be careful not to
damage the O-Ring or the exciter windings.

To fully secure the N side shield, screw the tie rods of the 5 threads to the D side shield and then work
crosswise to fully secure the N side shield by being careful not to damage the O-Ring.

After securing the shields, remove the 4 tie-rods and secure it permanently following the procedure 6.5.

Complete the assembly of the N side shield by securing it to the terminal box and by resetting the
connection of the terminals of the exciter stator ,(+) and (-), to the regulator. Use a clamp to lock the
wires.

Reassemble the protections on the N side and the protection on the D side.
For single bearing generators:
WARNING! Never loose or remove the tie rods blocking the bearings of the generator, as it is not required.

After distancing the drive motor, block the disk to the fitting with 2 appropriate clamps to make sure the
rotor doesn't accidentally come out.

Remove the protections of the N side shield.

Position the generator in a vertical and stable position using the eyebolt present on the fitting.

Screw an M10 eyebolt on the extension of the shaft and, after having removed the clamps, slip the rotor
out by making sure the casing is securely kept in place.

Remove the O-Ring from the seat in the N side. The O-Ring must always be replaced every time you
disassemble the rotor.
Use an appropriate extractor device to disassemble the bearings.
Carefully install the bearings on the shaft, preferably by heating them at about 80-90°C.

Apply an even layer of LGAF 3E (SKF) grease on the entire surface of the ring outside of the bearing
and on the entire surface of its seat of the N side shield (without an O-Ring), using an appropriate tool
(brush or spatula). Excessive thickness could lead to complications during the assembly of the bearing
on the shield.

Position the new O-Ring in the seat of the N side shield.

Insert the rotor vertically (with the bearing cooled) by being careful not to damage the O-Ring; if the N
side bearing does not fully fit in the seat, apply pressure on the head of the shaft until the rotor fully fits.

After having slipped the rotor inside, lock the disc to the fitting using 2 appropriate clamps to prevent the
rotor from accidentally falling when positioning the generator in a horizontal position.

Position the generator in a horizontal position and reassemble the protections on the N side of the
shield.

Invert the sequences of the operations described for disassembly.
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