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4.3.4 Test procedures. - Material tests. - While it is not the intention of this specification, in general, to require that all
the material used in the construction of motors be tested in accordance with the requirements of specifications
referred to in each individual case, the Government shall require such material tests whenever it considers it
necessary to ascertain that. the quality of a material used is at least equal to the material specified herein and
covered by the referenced specifications, or as shown on the manufacturer's approved drawings. Resistance. - The resistance of the windings and the temperature at which they are measured
shall be taken and recorded. Lubrication.  - The effectiveness of the lubricating system with the motor in its normal position
shall be observed during the progress of the other tests, or by special test, as the circumstances may warrant.
Navy approved lubricants similar to those required for service operation shall be used. It shall be demonstrated
that the motor lubrication is satisfactory, that the specified limitations of the bearing temperatures have not been
exceeded, and there is no suction of lubricant into the electrical windings under any operating condition,  The test
report shall indicate that such tests have been made. Airborne  noise. - Observance shall be made of motor noise during the progress of testing to deter-
mine that the motor is free from any degree of noise comparably greater than that inherent in the given type and
size of motor. Dynamic balance. - By instrument. - The mechanical balance of the completely assembled motor (and any special
attachments such as brakes or overspeed switches) shall be measured. Motors having a varying speed but no
definite no-load speed shall be tested at twice their rated speed. The method of test shall be as follows:
(a) Place the motor on an elastic mounting so proportioned that the up and down natural
frequency shall be at least as low as one-quarter of the operating speed of the motor.
To accomplish this, it is required that the elastic mounting be deflected downwards
at least by the following amounts due to the weight of the motor. The deformation of
the mounting should in no case be more than 1/2 the original height of the elastic
Compression (inch)
Revolutions per minute
(b) A reliable vibration indicator shall be employed.
(c) The amplitude of vibration shall be measured on the bearing housing in the direction
giving the maximum amplitude, with the motor running, the axis of the shaft in normal
position and at normal voltage. The motor shall be balanced with 1/2 a standard key in
the keyway; that is, a key of full length, flush with the top of the keyway (where applicable). By hand. - The balance shall be checked by "Touch" without the necessity of mounting on an
elastic base. If the motor feels to vibrate excessively it shall be retested in accordance with 4.3.4. 5.1 to
determine whether or not the dynamic balance is within the acceptable limit. End play. - Horizontal sleeve-bearing motors shall be tested for "end-play" while at standstill by alternate-
ly pressing and releasing the rotor shaft at each end. The requirements of 3. shall apply. AU ball bearing motors shall be tested for end play at standstill. The requirements of
as applicable and MIL-P-17840 apply. No-load input data. - The no-load input data test shall consist of taking a no-load input reading with
rated voltage and frequency applied at the motor terminals. Where the rotor of the motor is supported by the

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