| Tweet |
Custom Search
|
|
|
||
 TM 55-1905-217-34
(2) Remove eight pole shoe screws (12), four pole shoes (13) and two field coil assemblies (14 and 17) from the
field frame (1).
(3) Remove field coil insulating strips (15 and 16).
(4) Remove two ventilators (11).
(5) If necessary, remove terminal stud nut (6), terminal stud lock washer (7), terminal stud nut (4), lockwasher (7),
washer (3), stud insulator (8), insulated stud bushing (9) from the field terminal stud (5).
(6) Remove field terminal stud (5) from frame (1) and remove washer (3) and inside insulator washer (10) from
stud.
g. Cleaning.
(1) Use inhibited methyl chloroform to remove dirt and grease from all parts except the armature and fields.
NOTE
Refer to BuShips Instructions 6260.5 SER 660-50513 dated 7 October 1958 and change
No. 1, SER 660-4980 dated 19 January 1959 for characteristics, toxicity, flammability effect
on material and application of inhibited methyl chloroform.
(2) Do not clean the armature by any degreasing method since this would damage insulation and thereby possibly
ruin the armature. To clean, wipe with a clean cloth slightly dampened with inhibited methyl chloroform.
(3) General cleaning of the commutator is done with No. 0/2 flintpaper (Federal Specification P-P-111). If the
commutator is worn, out-of-round by more than 0.003 inch, has high mica, filled slot, or is burned, mount the armature by
the shaft bearing surfaces in a lathe and take light cuts until the commutator is completely cleaned up.
NOTE
Make cut not deeper than necessary.
(a) Undercut mica 1/32 inch.
(b) Remove all burrs with 0/2 flintpaper.
(4) The field coils should not be cleaned by any degreasing method, since this would damage the insulation and
might ruin the windings. Clean by wiping with a clean, dry cloth. Be careful in handling the windings to avoid breaking or
weakening the connecting straps between windings. If the field insulation is charred or chafed so that the windings are
exposed, it is sometimes possible to rewrap them with insulating tape (0.007 x 1/2 glass tape-Specification Mil-I-3158) and
paint them with insulating varnish (Specification Mil-V-1137 grade CB). This operation must be executed with care and
neatness since excessive bulkiness of the tape will prevent reassembling the windings under the pole shoes in the proper
manner. Soldered connections must be made with rosin core solder (Federal Specification QQ-S-571).
h. Inspection and Repair.
(1) Brushes. If the brushes are worn down to 5/16 inch (original length 1/2 inch), replace brushes. Make sure that
the pigtail leads are tight in the brushes and that the clips are fastened securely to the leads.
(2) Brush springs. The brush springs should have sufficient tension to provide the proper pressure between the
brushes and commutator after the unit is assembled. This may be checked by placing the armature and commutator end
frame together in their normal operating position and then placing the brushes in their holders with the springs in place so
that the tension of the springs against the brushes can be measured with a spring gauge. Correct spring tension should be
36 to 40 ounces. Replace springs if tension is not correct.
(3) Sleeve bearings. If the bearings are worn more than 0.005 inch beyond maximum dimension, as listed below,
they should be replaced. Wear will be greatest on the side which sustains the greatest thrust during cranking. After a new
bearing is pressed into place, cross drill oil hole. Ream to finish size, as listed below, and remove burrs in oil passage.
Finish size of bearings are:
Drive end housing
bearing, ID ................................ 0.8145......... 0.8165 inch
Middle bearing, ID ..................... 0.997........... 0.999 inch
Commutator end
bearing, ID ................................ 0.562........... 0.564 inch
(4) Brush holders and parts. If the brush holders, spacer plates, insulators, etc., are bent, warped, cracked, burned,
or otherwise damaged, replace parts as needed.
(5) Bendix drive assembly. The spring clutch Bendix drive assembly is serviced by replacing complete unit. The
unit must be in good condition, with parts tightly fastened together. If pinion teeth are worn, burred, or chipped, replace
Bendix drive assembly.
(6) Miscellaneous parts. Any defective insulator, screw, washer, lead, stud, plate, etc., should be replaced.
Cracked, bent, worn, burned insulators or washers are defective. Studs or screws which are bent, battered, broken, or
which have crossed or damaged threads, are defective. Leads which have broken strands or frayed insulation are
defective.
i. Testing.
(1) Armature.
(a) Ground. The armature leads become grounded to the armature laminations
4-20
|
||
|
||
