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GEK–91584D, Vertical Drilling Motor, Type GE752
66
3. Attach the brush–shunt terminals to the brush-
holder body under the screws provided.
4. Inspect the interior of the machine for foreign ob-
jects. Install the commutator covers on the motor
and check for proper fit and latch operation.
5. Clean the terminals.
HUB MOUNTING
Hub Fitting
NOTE: GE does not supply the hub for vertical
drill motors. This procedure is included for cus-
tomer use as a reference when installing the
hub.
To prevent a hub from slipping, it should have at least
75 percent fit on the shaft; i.e., at least 75 percent of the
tapered bore of the hub should be in contact with the ta-
pered fit on the shaft. Before mounting a hub, check and
correct the fit as follows:
1. Lightly cover the bore of the hub with a blueing
compound such as Prussian Blue.
2. Snap the cold hub forcefully onto the shaft.
3. Mark the relative angular position of hub with re-
spect to the shaft.
4. Remove the hub from the shaft. A convenient
method of removal is by the use of two finely ta-
pered steel wedges (hardened and ground)
which are carefully driven between the hub and
the bearing outer sleeve on the shaft.
5. Inspect the taper fit of the shaft; blueing of the
hub bore should now show on the shaft. If at least
75 percent of shaft surface shows traces of blue-
ing, the fit is satisfactory. If, however, only a few
spots of blueing show on the shaft, the fit is not
satisfactory.
6. Dress down the blue spots on the shaft very light-
ly with a fine emery cloth such as No. 400A Trie-
mite.
7. Blue the hub bore again (see Step 1) and repeat
Steps 2, 4, 5 and 6. Be sure to place the hub onto
the shaft in the same position as marked.
Generally, the fit will be improved, but the forego-
ing procedure may have to be repeated several
times to obtain a 75 percent fit.
Under no circumstances use a lapping com-
pound since lapping will produce a shoulder at
the large end of the tapered fit. A shoulder will
prevent a perfect fit when the hub is mounted
hot; i.e., when it is mounted in the advanced posi-
tion.
8. After a good fit has been obtained, thoroughly
clean the shaft and the hub bore to remove all
blueing, oil or grease. Then mount the hub.
Hub Mounting
1. Thoroughly clean the hub fit on the shaft and
bore of the hub (see the procedure in the Clean-
ing section). Remove any scoring on the shaft or
hub bore.
2. Spot the cold hub on the shaft by hand and check
for at least 75 percent fit. See the “Hub Fitting”
section. If necessary, dress the shaft to obtain
this fit.
3. Trial mount the cold hub onto the shaft. Measure
and record the position of the hub with respect to
the end of the shaft. Take measurements with a
micrometer advance gauge similar to that shown
in Fig. 41. Zero the gauge.
Mark points of measurement, and mark across
the end of shaft and hub face so that the hub,
when heated, can be mounted in exactly the
same angular position, and so the advance mea-
surement can be made from the same point.
4. Mount the hub hot onto the shaft so as to secure
an advance from the cold position to the hot posi-
tion along the axis of the shaft as indicated in this
section. The ESTIMATED difference between
shaft temperature and hub temperature (temper-
ature rise) which will provide this advance is also
given. The temperature difference is only an esti-
mate and should be adjusted (if necessary) to
provide the advance within prescribed limits.