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MIL-M-17413A(NAVY) Ball or roller bearings. - When ball or roller bearings are used, the following require-
ments shall apply: Grease cups. - Compression cups shall be used where grease is a means of lubrication
and relubrication of bearings is required but the cups shall be furnished as an onboard repair part item
(see table III). The grease cup shall not be mounted on the motor and the threaded hole used to attach the
grease cup shall be provided with a pipe plug. The grease pipes, where used, shall be left on the motor
and the end fitted with a pipe plug. Seals. - Except where double sealed ball bearings are used, the housing shall provide
for a seal on both of the bearings to prevent the leakage of oil or grease along the shaft. Housing construction - Except in the case of split frame motors the bearing housing
shall be so constructed as to permit ready removal of the end bracket without the necessity of removing
the bearings. Addition of grease lubricant. - Where grease lubrication is used the correct amount of
lubricant shall be added to the motor before the motor leaves the place of manufacture. Sleeve bearings. - General. -  Ample bearing surface shall be provided for each sleeve bearing. in general,
sleeve bearings shall be of the split type to permit their removal without necessity of removing the
armature from the frame or removing equipment mounted on the shaft. Motors having rotors weighting
less than 200 pounds may use either the split or solid-bushing type of sleeve bearing. Lubrication. -  Sleeve bearings shall be lubricated by means of an efficient ring, mask,
or force feed lubrication system as required. The number of oil rings shall be such that no ring is
required to distribute lubricant for an axial distance greater to 3 inches on either side of the ring. Bearing housing. -  The housing shall be designed to permit the oil rings to rotate freely
up to the maxinum degree of inclination. The rings shall not rub or strike against the sides or ends of the
oil reservoir, and shall not show a pronounced irregularity of movement. A means shall be provided to
prevent the rings from being thrown out of place when the vessel is permanently listed, rolling or when
subject to shock. The housing shall provide for a close-clearance metallic seal on both sides of the bear-
ings to prevent the leakage of oil along the shaft. This is in addition to the deflecting flanges or slingers
required on the shaft. Provision shall be made to insure against the suction of oil vapor into the interior
of the motor. Provision shall also be made for observation of the oil rings while the motor is running.
These openings shall be made oiltight by a cover secured by screw plugs, or other suitable means. Filling. -  An openidng or standpipe for filling, for preventing overfilling, and for indicat-
ing the oil level shall be provided in the reservoir arid shall be fitted with an oiltight plug or cap to pre -
v t the escape of oil due to the motion of the vessel. The diameter of the filling opening shall be not less
than 1/4 inch for machines built in frames of motors corresponding to 3 horsepower, continuous rating,
at .,800 r. p. m. and not less than 3/8 inch for larger machines. Provision for measuring speed (explosionproof and explosionproof fan cooled exclude(i). -
In all motors having a single shaft extension, provision shall be made for the measurement of speed
with a hand type tachometer. This may be accomplished either by extending the shaft flush with (or
slightly beyond) the outer face of the bearing housing, or by providing a hole and a plug in the outer end
of the bearing housing. If a hole and plug are provided in the end of the bearing housing, the hole shall
be not smaller than 9/16 inch in diameter and the design shall be such that the plug cannot be inserted in
the housing to such a depth that the plug will interfere with the end of the shalt. A lathe center or other
suitable hole shall be provided in the end of the shaft for the insertion of the tachometer tip.

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