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|  MIL-C-52980B
4.5.2.21.1.1 Rail impact test procedure. This test is conducted by mounting the test item on
a railcar in its rail shipment configuration and then performing a series of at least four impacts.
The first three impacts shall be at 6.4, 9.7 and 13 km/h (4, 6 and 8 mph), respectively, in the
same direction. The fourth shall be conducted at 13 km/h in the reverse direction. All four
impacts shall have a tolerance of +0.8, -0.0 km/h. If the test commodity can be shipped in two
orientations (such as lengthwise and crosswise on the rail car), the four impacts shall be repeated
for each orientation.
Step 1. Position from one to five rail cars on a level section of track. Satisfy the following
conditions:
a. Adjust the total weight of the car assemblage (see above) to at least
114,000 kilograms (250,000 pounds).
b. Compress the couplers between cars to take up any slack.
c. Set all of the air and hand brakes on the car(s) to be used.
d. Secure any load in or on the car(s) to prevent sliding or shifting; any movement
greater than 5 cm shall be justification for retest.
d. The end of the buffer car to be struck must have a standard draft gear.
Step 2. Mount the test item on the test car. The test car shall be equipped with standard draft
gears and conventional underframes. Mounting of the test item shall incorporate the standard
loading and bracing method as shown in section 6 of the Association of American Railroads
(AAR) "Rules Governing the Department of Defense Materiel on Open Top Cars". No exotic or
unusual tiedown methods shall be used; any non-standard loading and bracing must be approved
by the Military Traffic Management Command Transportation Engineering Agency
(MTMCTEA), ATTN: MTT-TR, P.O. Box 6276, Ft. Eustis, VA 23606-0276 (or its European
equivalent) prior to testing. Substitute (dummy) test items must be of equal weight and weight
distribution as the actual test item and similar in shape. The arrangement of the test item and its
blocking and tiedown to be tested shall be identical to that proposed and approved by
MTMCTEA ( if non-standard).
Step 3. Situate the test car between the buffer cars and the locomotive, and pull the test car at
least 65 meters (200 feet) from the buffer car(s) along a level section of track ( a minimum
distance to achieve the required locomotive speeds). Brakes are set on the buffer car to provide a
more conservative test.
Step 4. Position the knuckles of the buffer and test cars for coupling.
Step 5. Install a timing device to measure the test car speed ( + .1 km/h) just prior to impact
with the buffer car(s). Suggested methods include electronic timing (microswitches) and radar.
The use of torpedoes and a stopwatch is permissible but not recommended because of the
inaccuracies involved.
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