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)

3.5.4 Pin/bushing design and construction. Unless otherwise specified (see 6.2),

(reference dimensioned bushing drawings) the thickness of the elastomeric sections bonded to the

pin shall be such that compression of 35 to 40 percent of the original thickness will result when

installed in the intended application. Unless otherwise specified, the width of the sections shall be

not less than two and one-half or more than three times their thickness before compression. The

contractor shall be responsible for the volume of bushing properly filling the total volume for

which it is intended within +5 percent (95 to 105 percent of available volume). The bushing shall

not protrude beyond nor be recessed inside the shoe in which it is assembled beyond the limits

shown on applicable drawings. Unless otherwise specified, the bushing bore of the track shoe

body shall have a surface roughness height between 63 and 250 microinches (see 4.7.1.14).

3.5.4.1 Concentricity. The pin with the elastomer bushing thereon, assembled in the

applicable shoe (or simulated bore), shall be concentric with the bore of the shoe (or simulated

bore), so that the elastomer thickness is uniform within +1/64 inch.

3.5.4.2 Bushing adhesion. When tested in accordance with 4.7.1.10, the load required to

separate the elastomeric sections from the pin/sleeve shall be not less than the values shown

below. The elastomer pulled off and that remaining on the part shall show no evidence of any

defects including cracks, blistering, or porosity at the conclusion of the test. Discontinuity

(non-knit) of the elastomer resulting in any indication of separation of the elastomer shall be cause

for rejection.

Diameter of pin

Minimum load

(inches)

(lbs/inch width)

5/8

3/4

1-1/8

1-1/4

1-5/16

NOTE: When exact size of pin/sleeve is not shown above, use the value of load for the

next larger pin/sleeve diameter.