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Page Title:
Reliability and maintainability |
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|  MIL-S-46777C
(h)
On a cushion base of earth or sand, except for refuse specials, other semitrailers
load and dump a load of oversize boulders, shot rock, or concrete rubble having a
largest diameter dimension of 5-feet or larger; dump with tailgate hinged at the
bottom or tailgate removed.
(i) Dump payloads in a fixed location for stockpiling.
(j) Dump in a controlled uniform spreading lift of the payload while traveling forward.
(k) Dump the payload with the semitrailer on a side slope of at least the minimum slope
shown in figure 2 (no wind conditions).
(l) Except for refuse specials, other semitrailers dump the hot mix payload into the
hopper of a bituminous paver, of the wheel roller type or simulate dumping of hot
mix by use of pea gravel.
(m) Demonstrate the dump body hoist system drift by insuring that the semitrailer is
loaded with an evenly distributed load in the dump body to not less than the
semitrailer's rated GVWR. Hydraulically raise the dump body from travel position
to not less than 8-inches and not more than 18-inches, measured not more than
36-inches rearward from the front of the dump body. Place the dump control in the
"Hold" position and place nonyielding, post type supports on the curb and road
sides of the body exactly 2.0 inches lower than the hoisted, measurement point
stated above. Observe the hoist system drift and measure and record the initial and
final body position after a 15-minute time period.
(n) Check the hydraulic system throughout all testing. Install a gage into the pump
suction line immediately adjacent to the pump inlet and install another gage into the
pump outlet at the required pump test point. Monitor the gages periodically during
the testing and record readings.
Failure to load, haul, and dump as specified herein or any evidence of instability, malfunction,
permanent deformation, or breakage such as stress cracking of exterior paint, weld failure,
bending of framing or reinforcing members, binding or leaking of the dumping mechanism,
misalinement or hoist-system, drift in excess of the limit specified, touching or resting of the
dump body on any support, or nonconformance to 3.3 through 3.13 shall constitute failure of this
test.
4.5.2.4.1 Reliability and maintainability. When specified (see 6.2), the Government will
perform the following two tests:
(a)
Mean-time-between-failure. The semitrailer shall be tested in accordance with
4.5.2.4 for sufficient length of time to reach a decision to "accept" or "reject" in
accordance with MIL-STD-781, test plan VI. A "failure" for the purpose of this
test is defined as any random malfunction which causes degradation below the
operating condition required to continue this test and cannot be remedied within
4 hours. Nonconformance to 3.3.5.1 shall constitute failure.
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