Number of repair armatures (see table III).
Repair sets of gears (see table III).
Repair radio noise suppression equipment (see table III).
Repair parts boxes (see 22.214.171.124).
Whether suppression harnesses and specific radio noise limits are are required
(see 126.96.36.199 and 188.8.131.52.2).
Direction of rotation (where non-reversible).
Speed regulation of varing speed motors (see 184.108.40.206. 4).
Whether nonmagnetic motors are required (see 220.127.116.11).
Whether shipment is for domestic shipment, immediate use; domestic shipment
involving storage 180 days or less; domestic shipment involving stortage more
than 180 days; or over (see 5.1).
For submarine service only:
(1) Rated voltage and voltage range (see 3.7.1).
(2) Duty of short time, varying or intermittent motors (see 18.104.22.168.2).
(3) Duty of special voltage motors (see 22.214.171.124.3).
(4) Winding and speed classification (see 3.7.2).
(5) Enclosure, including details for special enclosures (see 3.7.3).
(6) Whether an overspeed trip device is required (126.96.36.199).
(7) Whether bearings specially selected for quiet operation are
required (see 3.7.10).
(8) Degree of balance if other than "Precision" (see 3.7.12).
6.3 Reduction of audible noise. - As a means of reducing audible noise, special attention should be
given the following:
1. Number of slots per pole pitch.
2. Number of slots magnetically under one pole.
3. Slot frequency as a function of natural frequency of the frame.
4. Skew of slots or pole tips.
1. Elimination of brush chatter.
2. Stiffeners of brush rigging.
3. Aerodynamic design of the ventilating or cooling system.
4. Mechanical balance.
6.4 Reduction of radio interference. - As a means of reducing radio interference, special attention
should be given to the following:
The use of interpole windings.
The use of compensating windings.
Increasing the number of armnature coils and commutator bars.
The use of shallow armature slots.
The use of short-pitch armature windings.
Reducing concentricity between commutator and bearings.
Balanced design to eliminate shaft and bearing currents without the use
of auxiliary brushes.