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MIL-M-17059A(SHIPS) Direction of rotation. - Nonreversible motors shall be marked in a permanent manner to in-
dicate the direction-of rotation. Seals. - The housing shall provide for a close-clearance metallic (nonrubbing) seal on both
sides of the bearings to prevent the leakage of oil or grease along the shaft. This is in addition to bearing
shields or slingers required on the shaft. Friction type seals may be used to supplement the close-
clearance metallic seal on motors for certain applications; for example, watertight and submersible motors.
Such sealing arrangements shall however, be satisfactory to the bureau or agency concerned (see 3.1.21. 4).
Friction type seals shall be secured in their housing and on the shaft to prevent rotational or axial movement
in the housing or on the shaft. Pump motors. - The following additional requirements shall apply to all pump motors as
(a) For dripproof protected pump motors, the air intake at the pump end of the motor is permitted
subject to the air intake being at right angles to the shaft (no openings in the end shields
parallel to the shaft shall be permitted).
(b) For all motors (except motors supplied with friction type seals as used in submersible and
watertight motor enclosures) a slinger with guard shall be provided on the motor shaft im-
mediately outside the end bracket to prevent entrance of water into the bearing housing. The
slinger shall have an external diameter of not less than 1.5 times the shaft diameter and an
axial clearance between the end shield and frame not greater than 30 roils. Where the
slinger-end shield or the pump design or both is such that no injury to personnel would result
and no entrance of water into the bearing housing would take place without the guard, the
guard need not be furnished. Omission of the guard shall be approved by the approval activity. Motors for submarine service. - In addition to the requirements of 3.1 through and including, the following requirements apply: Enclosure. - The enclosure shall be one of those listed under 3.1.8 or shall be special as
specified (see 6.1), except that dripproof protected motor shall meet the requirements of MIL-STD-108 at
45 degrees from the vertical in lieu of 15 degrees. Mounting. - Horizontal motors shall be suitable for either deck or underside suspension.
Dual ended ventilated (air inlets in both end shields and air outlets in frame) dripproof protected horizontal
motors shall be considered suitable provided a shield is designed to meet the necessary dripproofness re-
quirements when the motor is suspended underside.  This shield shall be provided when required by the
contract or order; however, it shall be shown on the motor drawing, whether the shield is or is not fur-
nished, in sufficient detail to permit fabrication by a Government activity.  To ascertain that the motor will
operate satisfactorily all tests on dual ended dripproof protected horizontal motors shall be conducted with
the shield on the motor. Ball bearings. - Unless otherwise specified in the contract or order, the bearings shall be
in accordance with 3.1.19. Center of gravity and radii of gyration. - The center of gravity of the motor and the radii
of gyration of the motor" about its "three principal axes shall be indicated on the drawing. Dynamic  balance. - The degree of balance shall be "Precision" in accordance with table X
unless otherwise specified in the contract or order. Inclination. - Motors shall be designed to operate satisfactorily under the following conditions:
(a) Horizontal motors:
(1) For sleeve bearing motors:
a. Shaft inclined 45 degrees, front end low.
b. Shaft inclined 45 degrees, rear end low.
c. Shaft horizontal, motor base tilted 45 degrees to right.
d. Shaft horizontal, motor base tilted 45 degrees to left.
(2) For ball or roller bearing motors:
a. Shaft inclined 45 degrees, front end low.
b. Shaft inclined 45 degrees, rear end low.

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