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MIL-DTL-11891 Track Shoe Sets, Track Shoe Assemblies, Track Shoe Pads And Track Shoe Bushings, Vehicular: ElastomerizedThis specification identifies the requirements for qualification and production control of track systems supporting U.S. Military Tracked Vehicles. This specification is intended primarily for the qualification of elastomeric compounds used in the fabrication of track and track components and to ensure that the quality and performance established at qualification is maintained throughout production. The contractor is held fully responsible for the entire assembly/component including all non-elastomeric components and fasteners.

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MIL-DTL-11891G(AT)

TABLE I. Bushing property tests.

Specification

Tolerance

Test requirements

ASTM

paragraph

(see note)

3.3.3.2

D792

+0.020

Specified gravity

3.3.3.3

D2240

+5 pts

Hardness

D412

3.3.3.4

+16%

Tensile strength

D573

3.3.3.5

+30 %

Tensile strength (aged)

(Change)

D412

3.3.3.4

+15%

Ultimate elongation

D573

3.3.3.5

+40%

Ultimate elongation (aged)

(Change)

D412

3.3.3.4

+17%

Tensile stress (modules)

@ 200% strain

E1131

3.3.3.6

Thermogravimetric analysis

D2084

3.3.3.7

Vulcanization using oscillating

3.3.3.7

disk cure meter

D429

3.3.3.8

Adhesion

3.5.4.2

D395

3.3.3.9

Compression set

D2137

3.3.3.10

Brittleness point of flexible

ACPT/REJ

polymers:

None

GC mass spec

3.3.3.11

3.5.3

NOTE: The contractor shall provide all test results of all lots of elastomeric materials

used in the preparation of all qualification hardware when tested to the

requirements of table I. During production, the contractor will be required to

maintain the production values within the tolerances specified in table I.

3.3.3.3 Hardness - durometer. Hardness tests will be performed on laboratory specimens

from bushing compounds subject to qualification in accordance with ASTM D2240. Hardness

tests shall be conducted on 3 samples each of the unvulcanized compounds taken from the final

mixing stage as well as 3 samples of the vulcanized finished components. All data generated as

the results of these two tests shall be reported to the Government. The production tolerance for

hardness will be +5 from the average value established at qualification (see 4.7.1.2).

3.3.3.4 Physical properties of bushing compounds. Physical property tests will be

conducted on each compound submitted for bushing qualification in accordance with

ASTM D412. All test results will be reported to the Government. For production of qualified

bushing compounds, the adjusted value established following qualification tests (3.4.1.2) , shall be

held to the following tolerances: +16% for tensile strength, +15% ultimate elongation, +17% for

200% modulus (see 4.7.1.3, 4.7.1.5 and 4.7.1.7).