MIL-DTL-17901C(SH)
TABLE II. Physical requirements for nonmetallic backing - Continued.
(class III, class IV, and class V bearings only)
Class III
Class IV
Class V
Test in
Units of
required test
required test
required test
accordance
Remarks
Property
measurement
value
value
value
with
10 Samples
tested with
Impact
FT-LB/IN
0.8 min
----
----
ASTM D256
Method "A"
resistance
and A 45-
degree notch
Immersed 24
Percent of
hours at a
Water
0.2 Percent
1.0 Percent
0.2 Percent
ASTM D570
water
specimen
absorption
max
max gain
max gain
volume
temperature
of 75 + 5 °F
Percent of
1.0 Percent
1.0 Percent
1.0 Percent
4.6.4.1 and
Oil
----
specimen
max
max gain
max gain
4.6.4.3
absorption
volume
1/
Ultimate tensile strength is derived from the flexural modulus results.
2/
The specimens shall be curved. The hoop and axial specimens shall have a span to depth ratio of 16:1. See
4.4.6.b.
3.2.4 Recycled, recovered, or environmentally preferable materials. Recycled, recovered, or environmentally
preferable materials should be used to the maximum extent possible, provided that the material meets or exceeds the
operations maintenance requirements, and promotes economically advantageous life cycle costs.
3.3 General requirements. The class, type, size, dimensions and dimensional tolerances shall be as specified
(see 6.2). (Type is a subdivision of class that is flanged, unflanged, optional design type I, II, or III as identified in
Drawing 803-1385664. Size refers to basic dimensions that determine bearing size that is shaft sleeve diameter,
bearing length.)
3.3.1 Manufacturing of bearings. Unless otherwise specified (see 6.2), stern tube and strut bearings shall be
manufactured and fabricated in accordance with Drawing 803-1385664, except class V. Class V bearing drawings
are to unique to each application, there is no standard drawing.
3.4 Bond life. The adhesive, which bonds the rubber facing to the bearing backing, shall maintain the bond for
the life of the bearing and shall not show signs of separation along the edges. Bearing test specimens when
subjected to pull tests shall meet the requirements in accordance with 3.4.1 through 3.4.5, except for class V
bearings that shall meet the requirements of paragraph 3.4.6. Test specimens shall not be subjected to more than one
type of aging per specimen.
3.4.1 Adhesion before aging. The adhesion of the rubber facing material to the backing for each strip shall
have a minimum value not less than 20.0 pounds when tested in accordance with 4.6.5.
3.4.2 Adhesion after oven aging. The adhesion of the rubber facing material to the backing for each strip shall
have a minimum value not less than 20.0 pounds when tested after being subjected to warm circulating air for 96
hours in accordance with 4.6.5.1 and tested in accordance with 4.6.5.
5
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