MIL-DTL-17901C(SH)
visual, dimensional, and hardness tests shall be performed on all of these selected bearings in the as-manufactured
condition (prior to cutting into specimens) in accordance with 4.5.1, 4.5.2 and 4.6.1 respectively. Unless otherwise
specified (see 6.2), any bearing/stave in the sample containing one or more visual, dimensional, or hardness defect
shall be rejected and 100% inspection of all bearings/staves for that particular test is mandated. After successful
completion of visual, dimensional, and hardness inspection, a single bearing shall be selected from the sample
bearings to be used for supplying all required tests specimens. The bearing shall be cut into circumferential
segments as shown on Figure 2. Each segment shall be cut into 6-inch (+0.5, -0 inches) lengths. Longitudinal cuts
shall be made along the length of the cylindrical bearings that cut completely through the rubber and backing
separating the bearing into a number of longitudinal segments. The plane of the saw shall pass through the axial
centerline of the bearing and through the center of molded grooves that exist between the simulated stave shapes that
run the length of the bearings (see Figure 3). For class V, test specimens shall be taken from prolongations removed
from the as-manufactured part. A total of 25 test specimens for class II and IV and 30 for class V shall be required
for all of the tests.
b. Test specimens for tensile, elongation and hardness tests. Select six segments as prepared in 4.4.3.a
and buff facings flat (see ASTM D3183 for buffing procedures). Measure the hardness of the segments at this time
in accordance with 4.6.1. The rubber for tension and elongation tests shall be sliced from the surface of each of
these segments by means of a fine tooth band saw) and buffed to a thickness of not less than 0.060 inch or more than
0.120 inch in accordance with ASTM D412 (or D3183).
c. Test specimens for delamination tests. Select three segments as prepared in 4.4.3a. The rubber for
delamination testing shall be obtained by removing the rubber facing from the backing at the interface bond. From
each of the pieces cut a test specimen 3 inches by 1 inch (+/-1/16 inch) by the thickness of the rubber.
d. Specimens for volume change tests. The rubber specimens for the volume change test shall be
obtained from the facing material of six bearing segments by removing the rubber facing from the backing. Buff the
rubber of each segment to a flat surface. Cut one specimen 2 inches by 1 inch (+/-1/16 inch) with a thickness not to
exceed 1/16 inch from the surface of the segments. These specimens are now ready for aging (see 4.6.4.2 and 4.6.4.3).
e. Specimens for adhesion bond testing. Select 10 test specimens for adhesion pull testing for classes II
and IV and 15 for class V and buff facings to ¼-inch (+/-1/16-inch) thickness (see ASTM D3183 for buffing
procedure). They shall each have two longitudinal cuts in the facing, equally spaced about the centerline, ½ (+/-1/32
inch) inch apart. The cuts shall go completely into through the rubber facing to a depth of approximately 1/16 inch
into the backing. The rubber on each side of the center strip shall be removed from the backing at the bond. This
leaves one ½-inch center strip per test specimen. The test specimens are now ready for the type of aging required by
the particular tests specified in 4.6.5.
4.4.4 Selection of samples and preparation of test specimens for conformance inspection stave bearings only
(class III). Selection of samples and preparation of the test specimens for conformance inspection (class III) shall
include following:
a. Sample stave bearings shall be statistically selected from each lot in accordance with Table VI. A
visual, dimensional, and hardness inspection shall be performed on each bearing of the statistical sample (in the as-
manufactured condition) in accordance with 4.5.1, 4.5.2, and 4.6.1, respectively. This portion of the conformance
inspection shall be successfully passed before proceeding with the preparation of test specimens for adhesion bond
testing. Unless otherwise specified (see 6.2), any bearing/stave in the sample containing one or more visual,
dimensional, or hardness defect shall be rejected and 100% inspection of all bearings/staves for that particular test is
mandated.
b. If the statistical sample passes the above inspection, select a sample stave specimen from each slab for
class III staves. Buff the rubber facing of the stave specimen to a thickness of ¼ inch (+/-1/16 inch). See ASTM
D3183 for buffing procedures. Cut one 6-inch (-0.0 inches) long specimen from one end of each slab or stave to use
in making the test specimens.
The rubber facing of the 6-inch stave specimen shall be divided into strips by means of longitudinal cuts
that go completely through the rubber and to a depth of 1/16 inch into the backing. A cut shall be made ½ inch (+/-1/32
inch) from each longitudinal edge of the stave facing and two longitudinal cuts shall also be made equally spaced
about the center line a distance of ½ inch (+/-1/32 inch) apart. This leaves a ½-inch wide center strip and two ½-inch
edge strips. The rubber facing between the center and edge strips shall be removed from the backing at the interface
bond. For adhesion testing, these three strips will be pull tested individually. (See Figure 1 for a cross section view
of a test specimen.) The test specimens are now ready for adhesion bond test in accordance with 4.6.5, except
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