MIL-DTL-14055G
d. The test cup shall be subjected to -40°F to -45.4°F (-40°C to -43°C) for 22 hours.
e. The cup shall be bent through an angle of approximately 90 degrees and immediately released.
The cold cup shall be handled in a manner to prevent warming.
f. Within a minute examine test cup for cracking and change in shape from original appearance to
determine conformance to 3.4.3.1.
4.7.4.2 Leakage. Cups when subjected to leakage testing shall meet the requirements in 3.4.3.2. The
following details and conditions shall apply:
a. The test setup shall include the following:
1. A cold chamber large enough to permit arrangement of the apparatus within, for checking and
operation without removal from the chamber.
2. A master cylinder and four wheel cylinders so connected that their operation closely
approximates the brake system in actual service.
3. A pressure gage.
b. The test setup shall conform to the following:
1. The brake cylinder containing the specimens under test shall meet the dimensional limitations
of a new cylinder.
2. The retractor spring shall be such as to require not more than 50 psi (3.45 bar) line pressure to
make a complete stroke at room temperature.
c. The specimens for test shall consist of one primary and one secondary master cylinder cup and
eight wheel cylinder cups.
1. The specimens shall be rinsed in isopropyl alcohol or ethyl alcohol and wiped dry with a lint-
free cloth.
2. The specimens shall not remain in the alcohol for more than 30 seconds.
3. The specimens shall be assembled in the test cylinders.
4. During assembly of the cylinder assembly, the cylinder walls shall be coated with and each
other part shall be dipped in brake fluid conforming to MIL-PRF-46176.
5. The cylinder assembly shall be assembled with the master cylinder in the test apparatus in the
cold chamber.
6. The system shall be filled with brake fluid conforming to MIL-PRF-46176 and all air bled from
the system. Boots shall not be used.
7. The assembly shall be subjected to a temperature of -67°F ± 2°F (-55°C ± 1.5°C) for 120 hours.
8. The pistons and cups shall remain in a static position during the first 72 hours of the test and
thereafter shall be actuated 6 strokes at 100 psi (6.89 bar) and 6 strokes at 500 psi (34.47 bar)
each 24 hours, that is, after 72, 96, and 120 hours.
9. The strokes shall be approximately 1 minute apart and the pistons shall return to the stop after
each stroke.
10. The pressure in the system shall be noted and the cylinder examined for leakage during the
test, to determine conformance to 3.4.3.2.
4.7.5 Resistance to fluids at elevated temperatures. Wheel cylinder cups when subjected to the elevated
temperature test shall meet the requirements of 3.4.4. The following details and exceptions shall apply.
a. The apparatus shall include:
1. A micrometer caliper, shadowgraph, or other device for measuring accurately in thousandths of
an inch.
2. Screwcap glass jars of approximately 1/2-pint (237 ml) capacity with screwcaps made of tinned
steel (no organic coating) and containing no gasket or liner.
3. An air oven conforming to ASTM D573 as specified in 4.7.3.
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