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|  MIL-C-18087A(SH)
3.4.7.8 Tooth finish. Tooth contacting surfaces acting as flexible
couplings shall have a surface finish of 32 roughness height rating (RHR) or
better. All other tooth surfaces shall have a surface finish of 63 RHR or better
3.4.7.9 Tooth corners.
Corners at ends of engaging dental teeth shall be
chamfered or rounded off.
3.4.7.10 Tooth crack inspection. Teeth shall be inspected in accordance
with MIL-STD-271 by the magnetic particle or liquid penetrant method after
completion of machining and heat treatment.
3.4.7.11 Tooth contact. Hubs and sleeves shall be checked in an aligned
position to assure that at least 80 percent of the teeth are in contact or as
specified (see 6.2).
3.4.7.12 Tooth stress calacula tions. Unless otherwise specified (see 6.2),
calculations shall be made at 125 percent of full-power torque for propulsion
clutches, and 110 percent of full-power torque for auxiliary clutches using the
contractor's procedure. When calculations are for stress or percent deformation,
the calculated values shall be less than allowable limits, if specified (see 6.2).
3.4.7.12.1 Tooth stre ss. The following calculations for dental tooth
elements of clutches shall be made:
(a) Hertzian contact stress in crowned dental teeth for clutch in
aligned condition with 100 percent of the teeth in contact,
calculated in accordance with the following formula:
Unless approved by the contracting activity, the calculated
value of Sc shall not exceed the following allowable values:
Minimum tooth
Maximum allowable contact stress
surface hardness
in pounds per square inch
28
Rc
8,000
38
Rc
12,000
49
Rc
15,000
56
Rc
18,000
59
Rc
19,500
(b) Pitch line shear stress in dental teeth for clutch in aligned
condition with 100 percent of the teeth in contact.
17
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