(3) Values of full load current, speed and watts differing by more than one percent of the
preshock test values.
(4) A mechanical unbalance of more than two times the value of unbalance specified in
(5) Either a bearing or oil temperature rise or both in excess of that permitted in table IX.
(6) Objectionable noise. - Any noticeable increase or decrease in noise of the motor when
operating at rated speed should be investigated and its cause determined. However,
if disassembly is required for this check, it should be made during the test specified
(7) Low dielectric strength. - The motor shall be operated to obtain approximately rated
temperature rise of iron and windings, then disconnected from its load or from its
source of power and a dielectric strength test made to check the condition of the insu-
lation. This dielectric strength test shall be made in accordance with 18.104.22.168 except
that it shall be made with an applied voltage equal to 65 percent Under these condi-
tions, insulation failures shall be cause for rejection.
(8) Failure to pass inspection. - The motor shall be disassembled following checks
22.214.171.124(e)(l) to 126.96.36.199(e)(7) inclusive, and inspected thoroughly for damage.
The extent of disassembly need be only to the point where the condition of the motor
can be easily observed. The effects of the shocks and subsequent check tests on the
structure, bearings, and insulation shall be carefully observed and recorded.
(f) Acceptable method of mounting on shock-testing machine. - The mounting adapters shown on
the following figure of MIL-S-901 shall be used:
(1) Fixture 4C for motors to be tested on the shock-testing machine for lightweight
(g) Number of motors to be tested. - Unless otherwise specified in the contract or order, one
motor of the longest core length in any one diameter and of similar construction out of each
group of enclosures listed below, shall be shock-tested:
Totally enclosed fan-cooled.
Explosionproof, group D.
Explosionproof fan-cooled, group D.
Submersible, all degrees.
If the manufacturer desires he may submit a motor frame of less than the longest core
length to the shock-test. However, satisfactory conformance with the shock requirements
will give approval only to motors having a core length equal to or less than the core length
of the motor tested.
(h) Disposal of shock-tested motors. -
(1) Motors which have been subjected to the high-impact shock-test and have failed to
conform to the requirements will not be acceptable, either in whole or any of the
(2) Motors which have been subjected to the high-impact shock-test and have success-
fully passed this test shall be considered acceptable as an item in the contract
provided the post- shock-tests specified hereinafter are satisfactorily passed and
provided the mechanical corrective measures specified hereinafter are satisfac-
torily met. Mounting flanges connecting directly to the driven auxiliary shall be