GE BC-375-E Preliminary Instructions page 17

screwing the screw in each terminal clamp. It is
not necessary or advisable to remove the terminal
clamp from the brush holders.
(e)
The bearing bracket can now be taken out
of the way and the armature withdrawn from the
frame. Take care not to injure the armature wind-
ings or commutator by rubbing against the field
poles. Do not lose any shim washers which may be
in the bearing housings, or which may stick to the
bearing. If any shims are present they must be
reassembled in the same housing.
(f) End Play Adjustment : A spanner screw is
provided on one bearing bracket for adjusting end
•play in the dynamotor.. This is properly adjusted
at the factory and ordinarily will not need to be
changed unless the armature is replaced. Before
making any adjustments with this screw, it is
necessary that two setscrews on either side of the
bearing be loosened. Then the spanner screw
should be turned out (counter clockwise) one turn.
Operate the dynamotor until it is hot (about 30
minutes.) The end play should then be adjusted by
turning the spanner screw as required until the
end play as shown on an indicator reading to
1/1000 inch, is between approximately 4/1000 to
8/1000 inch.
In case an indicator is not available an alternative
method of adjusting the end play is as follows:
Screw the spanner screw in until the bearing
starts to growl, then back it off immediately
N3
turn (45 degrees). This latter method must be
used with extreme care since if- the bearings are
set up too tight or allowed to remain tight for any
period of time they may be damaged. The set-
screws should then be tightened to hold the spanner
nut in position.
(g) In cleaning the ball bearings it is not neces-
sary to remove them from the armature shaft.
Simply immerse the bearing in a shallow pan of
clean carbon tetrachloride and wash all of the grease
from the bearing. The use of a small camel's-hair
brush will greatly aid the thorough cleaning of the
bearing. Change the cleaning solvent in the pan as
soon as it becomes dirty. Always use clean solvent
for the final rinsing of the bearings.
Do not allow the cleaning solvent to come in
contact with the commutators or windings. In case
the cleaning fluid is accidentally splashed on these
parts, wipe it off immediately. Make certain the
bearing is thoroughly clean and dry before repack-
ing with new grease. If the bearing is not to be
repacked with grease within a few minutes after
cleaning, flush it with a clean, light mineral oil to
protect the polished balls and races from rusting.
(h)
In reassembling the dynamotor unit, follow
in reverse order the procedure for disassembly.
Make certain that the two field leads are securely
attached to the proper terminal clamps on the low-
voltage brush holders and that the "slack " or
"loop" in these leads is "tucked" back of the
field coils. Do not loosen or remove the brush
holders from the bearing brackets. If a brush holder
is loosened or removed for any reason, replace it
securely in exactly its original position and check
to make certain the contact surface of the brush
fits the commutator perfectly. If necessary, sand-in
the brush to secure a good fit against the commu-
tator.
(5). TYPICAL PERFORMANCE: The dyna-
motor unit alone without the transmitter should
operate approximately as follows on a load test :
Input
Output
Volts Amperes
Volts Milliamperes
24.0
5— 7.5 1140-1160 0
24.0 14-16.5 1070-1090 220
24.0 20-22.5
1025-1050 350
Note : The input current above includes that
taken by the starting relay.
14