MIL-DTL-17060G(SH)
3.5.1.22.3 Housing construction. Bearing housing shall permit ready removal of the end shield without
removing the bearings. Motors with frame size less than 286 shall have removable inner bearing caps. Motors with
frame size 286 and larger shall have removable inner and outer bearing caps. Bearing caps shall be secured with
fasteners in such a manner that the fasteners shall be removable without dismantling the motor. Motors with
cartridge or double seal bearings need not have inner bearing caps.
3.5.1.22.3.1 Removal of bearing. Construction shall permit removal of the ball bearing by pulling on the inner
ring of the bearing.
3.5.1.22.3.2 Bearing preload washer or springs. The use of bearing preload washers, springs, or both shall be
permitted provided they are secured in the housing. The spring or washer shall be applied in such a manner as to
provide for temperature differential compensation specified in 3.5.2.1.5.2.
3.5.1.22.4 Caution plate. Where cartridge or double seal bearings are used, a plate bearing the words
"CAUTION: DO NOT LUBRICATE" shall be permanently attached to the motor. The plate shall meet the
requirements of 3.5.1.33.
3.5.1.22.5 Sleeve bearings and oil lubricated ball bearings. When use of sleeve bearings is specified (see 6.2),
motors having rotors weighing less than 200 pounds may use either split or solid bushing type sleeve bearings. Split
cylindrical sleeve bearings shall be used for rotor weights in excess of 200 pounds. Sleeve bearing construction
shall be such that unit loads do not exceed 150 pounds per square inch (lb/in2) and the length to diameter ratio does
not exceed one. Sleeve bearings shall be either Babbitt faced, bronze backed, or solid bronze.
3.5.1.22.5.1 Lubrication of sleeve bearings and oil lubricated ball bearings. Sleeve bearings shall be lubricated
by a self-contained gear, disc, viscous pump, or forced feed lubrication system as required. Lubricant for sleeve
bearings and oil lubricated ball bearings shall be in accordance with MIL-PRF-17331.
3.5.1.22.5.2 Oil discs. The number of oil discs shall be such that no disc is required to distribute lubricant for
an axial distance greater than 3 inches on either side.
3.5.1.22.5.3 Bearing housing. The housing shall provide for a close clearance metallic seal on both sides of the
bearings to prevent the leakage of oil along the shaft under all conditions of pitch, roll, or shock. This is in addition
to the deflection flanges or slingers required on the shaft. Provision shall be made to ensure against the suction of
oil vapor into the motor. Provision shall also be made for observation of the disc scrapers or pumps. These
openings shall be oiltight and have a cover secured by a positive lock and gasket. Surface area and oil sump volume
shall be adequate to transfer the heat generated in the bearing. Forced water or air cooling may be used. Bearing
seats shall be line bored to produce good bearing alignment. The bearing bore centerline shall deviate by not more
than 20 percent of the bearing clearance.
3.5.1.22.5.4 Filling. An opening or standpipe for filling, preventing overfilling, and indicating the oil level
shall be provided in the reservoir. It shall be fitted with an oiltight plug or cap to prevent the escape of oil due to the
motion of the ship. Positive venting shall be provided to assure pressure equalization in the motor. The diameter of
the filling opening shall be not less than ¼ inch for machines built in frames of motors corresponding to 3 hp,
continuous rating of 1,800 r/min, and not less than ⅜ inch for larger machines.
3.5.1.22.5.5 Threads. Straight threads shall be used on all plugs and fittings.
3.5.1.22.5.6 End play (sleeve bearings only). To ensure floating of the shaft in horizontal sleeve bearing
motors, there shall be at least 1/64 inch end play in either direction.
3.5.1.23 Rotor and stator core.
3.5.1.23.1 Securing core to shaft. Provisions shall be made to prevent rotation of the core on the shaft and axial
displacement of the core along the shaft. Keys, knurling of the shaft, or keys in conjunction with press or shrink fits
shall be provided to prevent rotation of the core around the shaft. Press or shrink fits without keys to secure the core
on the shaft to prevent axial or rotational movement of the core shall be as approved (see 6.11). Tack welding in
conjunction with these methods is permissible to prevent axial displacement of the core along the shaft.
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