MIL-PRF-85336B
a. The test pieces shall be rubber O-rings of 13 mm external diameter and 1.7 mm cross
sectional diameter, fabricated from rubber meeting the requirements of MIL-P-25732 (see 6.7).
b. The test temperature shall be 70 °C.
c. The change in mass of the test specimens shall be determined after 72 hours of contact
with the lubricant.
d. The mass gain produced by the lubricant under examination shall be compared with that
produced in O-rings of the same lot by a reference fluid containing 65 percent by mass of methyl-
phenyl silicone (50 centistokes (cSt)) and 35 percent by mass of bis (2-ethylhexyl) sebacate,
lubricant grade.
4.5.7 Emulsification resistance. Place 5 ± 0.1 mL of the lubricant in a 50-mL graduated
cylinder having an internal height of 16 to 20 cm and a ground glass stopper. To this add
25 ± 0.2 mL of heptane, at least 96 percent pure, and mix with the lubricant by shaking. Then add
20 ± 0.2 mL of distilled water and vigorously hand shake for 30 seconds. The mixture shall be
allowed to settle undisturbed at room temperature for 30 ± 0.5 minutes before measuring the
depth of the water layer formed at the surface.
4.5.8 Load carrying capacity. The test apparatus shall be that described by ASTM-D2670,
Sections 4 and 5, prepared according to section 10, and using the 20,000-N load gage calibrated
in accordance with ASTM-D2625. Sixty mL of the test lubricant shall be placed in the cup at
25 ± 5 °C and raised to immerse the V-blocks with the jaws slightly opened. Ensure that the
V-blocks and pin are surrounded by the lubricant and that no voids remain. The loading device
shall be placed on the jaw arms and the slack taken up. The test shall then proceed in accordance
with ASTM-D2625, Procedure B. A decrease in the load shall be considered a failure only if it is
so rapid that the load cannot be restored by use of the loading ratchet.
4.5.9 Storage stability.
4.5.9.1 Oil separation. A well-mixed sample of the lubricant shall be placed in an oil sample
bottle or other glass container, 30 to 50 mm in diameter, to a depth of 100 ± 3 mm. No lubricant
shall be on the walls of the container above the 100 ± 3 mm level. The depth of the oil layer
formed at the surface of the lubricant shall be measured after holding the sample at
50 ± 1 °C for 168 hours.
4.5.9.2 Apparent viscosity. After storage for 168 hours at 50 °C, the sample shall be tested
in accordance with the as received apparent viscosity test (see 4.5.4).
4.5.10 Machine gun performance. The lubricant shall be tested in an instrumented
M61A1/A-7E gun system. Before beginning the tests, the entire system shall be disassembled,
8
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business