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)

The constant 12.227 included factors for conversion of inches to centimeters and

to reduce to 95% volume. The calculation for each cavity is to be accomplished

for minimum fill by using the maximum diameter and average length.

d. The displaced volume recorded from 4.7.1.14.1b is to be compared to and be

equal to or greater than the calculated volume of 4.7.1.14.1c.

4.7.1.14.2 Maximum fill determination (unbonded). Using the unbonded bushing, the

following procedure shall be completed:

a. Perform steps in 4.7.1.14.1a and 4.7.1.14.1b.

b. Apply data from drawings and recorded sleeve diameters in the following formula:

Vmax = 13.515 (D min 2 -Di2 ) L

D min = minimum diameter of bore (inches)

= recorded diameter of pin or sleeve

= average length of bore or sleeve (inches)

Vmax = volume of cavity for bushing in cubic centimeters.

The constant 13.515 includes factors for conversion of inches to centimeters and

to increase to 105 percent volume.

c. The displaced volume recorded from 4.7.1.14.1b is to be compared to and be

equal to or equal to or less than the calculated volumes of 4.7.1.14.1b.

4.7.1.14.3 Maximum fill determination (bonded). Using the bonded bushing, the

following procedure shall be completed:

a. Provide one or more tubes, either steel or plastic, with a minimum bore diameter

and the length equal to 105 percent of the average bore length of the shoe body in

which the bushing is to be used.

b. Insert the bonded bushing in the tube.

c. One bushing from each cavity shall be tested.

4.7.1.15 Concentricity. Concentricity shall be measured with a depth gage or steel rule to

determine conformance with 3.5.4.1. Samples shall be taken in accordance with table V.

4.7.2 Track roadwheel path and ground pad.

4.7.2.1 Specific gravity. This test shall be performed to the requirements of 3.3.4.1.

During production, the test shall be performed on unvulcanized rubber sampled at the frequency

of one per batch at the final mixing. The results from these tests shall meet the tolerances

established from data acquired during qualification and the tolerances listed in table II.