3.3.4 Operating Life. The motor operating life shall be 25 hours
of cumulative operating time through repeated duty cycles, as specif-
ied in 3.3.3, for a total of 150 duty cycles. Acceptable perform-
ance of operating life is defined: the motor shall satisfactorily
complete the 25 hours of operation and, subsequently, the quality
conformance tests of 4.7 with the following modifications:
(a) Due to expected buildup of brush residue during motor
operation, the requirement on insulation resistance (184.108.40.206) shall
be not less than 10,000 ohms for motors that have been subjected
to life test.
(b) The requirement on no-load speed (220.127.116.11) for motors that
have been subjected to life test shall be 127 rpm maximum and 113
rpm minimum. The speeds in opposite directions, after life test,
shall not differ,by more than 6 rpm.
3.3.5 Strength of wire or terminal connections. Each of the elec-
trical connecting wires or terminals shall be capable of withstand-
ing a pull test of five pounds.
3.3.6 Brush fitment. Prior to quality conformance testing, in
order to fit the brushes to the commutator and stabilize motor char-
acteristics, each motor shall be opera-ted at 26.0 4.0 vdc for from
10 to 30 minutes in each direction, repeated for a number of such
cycles to give a total run-in time of at least 12 hours.
3.3.7 Commutation noise. The ac component of the motor current,
when running at no-load and at nominal voltage, shall contain a min-
imum of radiofrequency components and shall be relatively free of
other sharp discontinuities. The commutation noise-level shall not
exceed 0.75 volt when measured as directed in 18.104.22.168.
3.4 Environmental requirements. The motor shall be capable of
meeting all performance and product requirements of this specifica-
tion after being exposed to the following environments and conditions:
Motor shall be attached to fixture by its nor-
mal mounting features: to mount motor use 4 each,
MS-16997-33 Scr cap Soc Hd; MS-21042-08 Nut-Self
Lock; and NAS 620-8 Washer, Plain. Torque the
mounting hardware to 25 5 inch pounds. (See