18.104.22.168 Metal strips. - When metal strips or wedges are used in the armature slots for final
balancing, they shall be well insulated from the armature core and windings.
3.2.13 Field coils. - Field coils shall be thoroughly insulated from adjacent, conducting and grounded
parts and shall be positively secured so that they cannot become loosened by vibration. As far as
practicable, field coils of the same type shall be interchangeable. All motors shall have commutating
3.2.14 Field poles and shoes. - The design shall be such as to allow for adjustment of the air gaps.
The field poles and shoes still not be secured by dowels or otherwise in such a manner as to prevent
their ready removal, replacement or adjustment. It shall be possible to remove the field poles from the
frame without removing the armature.
3.2.15 Frame. - The frame shall be of rigid construction. If approved by the bureau or agency con-
cerned, frames of the larger size horizontally mounted motors may be split in two halves parallel the shaft
and in a horizontal plane so as to permit ready removal of the armature in an upward direction.
3.2.16 Feet. - Except for submarine motors (see 3.7. 5), the feet shall be machined and shall be
either cast integral with or welded to the frame. The feet shall be provided with round holes for holding
3.2.17 End brackets (explosionproof and explosionproof, fan-cooled excluded). - An accurately
machined shoulder joint shall be provided between the frame and the end b rackets. When so specified,
(see 6. 2), the design of the end brackets shall provide for, and the accuracy of machining shall be such
as to permit, the rotation of the bearing through 90 or 180 degrees in either direction to allow for bulkhead
or underside suspension of the motor. Resilient-gaskets shall not be placed between any bearing support
member and the frame. In the case of spraytight, watertight and submersible motors, the contact surfaces
between enclosing covers and the motor frame or end brackets shall be free from fins, burrs, or other
imperfections detrimental to watertightness, and shall be provided with gaskets suitably secured and
treated with graphite on the contact surface to prevent sticking. All sheet packing shall be securely
attached to the covers.
22.214.171.124 General. - Each end bracket shall be secured to the frame with not less than four hexagon-
head screws or bolts of suitable size and strength, Openings of adequate size and number shall be pro-
vided so as to give easy access to and a direct view of commutator, collector rings and brushes while
the motor is in operation. These openings shall be provided with covers and fastenings. The enclosing
covers (handhole or access-hole covers) shall be readily removable. The engaging bolts or locking devices
shall be attached to the frame, the end bracket, or the covers as the design Permits in such manner as
to prevent the bolts or locking devices from being misplaced or dropped into the machine during repair
operations. Except as specified in 126.96.36.199, ready access shall be provided to permit the measurement
of the air gap in at least four places approximately 90 mechanical degrees apart on both ends of motors.
3. 2.17.2 Aluminum end brackets. - Alum inure end brackets (see table IV) shall not support the total
weight of the motor or diven auxiliary unless approved by the bureau or agency concerned. Steel inserts
shall be provided for all threaded portions and bearing housing.
188.8.131.52 Ball bearing and roller bearing motors. - Motors equipped with ball bearings or roller
bearings which permit the measurement of the air gap by the method specified in 184.108.40.206, or by an
alternate indirect method satisfactory to the bureau or agency concerned, need not be provided with
apertures for checking the uniformity of the air gap.
3.2.18 Shafts. -
A shaft extension with keyway shall be provided to suit the driven apparatus.
3.2.19 Bearings. -
Bearings shall be of the ball, sleeve or roller type as specified (see 6. 2).