MIL-T-14521E
hand to assure proper functioning. The examination provisions may be applied
at the earliest practical point in manufacture at which it is feasible to
inspect for acceptance without risk of change in the characteristic by
subsequent operations. Failure of the contractor to provide objective evidence
that the trestle has passed the examination prescribed for it by the
contractor's iris.pectlcn system shall be cause for rejection.
The baseline measurement and
4.4 First Article test and test methods.
tests of 4.4.3. 4.4.4, and 4.4.5 shall be performed in the order given. and in
accordance with the requirements of 4.4. 1 and 4.4.2.
4.4.1 Testing machine. The test specified in 4,4.4, 4.4.5, 4.5.1. and
4.5.2 shall be conducted using a compression testing machine which is accurate
within five percent of the load being measured. The accuracy of the
testing machine, including the effects of off-center (eccentric) loading, shall
be verified in accordance with ASTM E4. Dead loads are considered unsafe for
test purposes and shall 1 not be used. All loads shall be applied through
platens of such sufficient thickness and hardness that they will not deform or
coin under the loads applied to the trestle. The platens shall be flat and
smooth and shall not restrain the trestle from tipping, moving, or deforming
during load testing.
4.4.2 Examination and measurements. All measurements shall be performed
while the trestle is resting on a surface which is flat and smooth within
inch.
If suitable. the lower platen of the testing machine may be used for
this purpose. The measuring device used shall be accurate within
inch.
The trestle shall be visually examined for cracked welds and other damage.
Following the examination, the trestle base length and width and the distance
from the surface plate or lower platen to the top of each lip of the saddle
shall be measured (see dimensin B of Figure 2) with the saddle and column
fully raised. Also, the distance between the bottom end of the column and the
platen shall be measured with the column in the lowest possible position
(see 3.6.2).
4.4.3 Baseline measurements. Friar to testing, but after the preload if
used (see 3.5.1). the trestle shall be examined and baseline measurements shall
be taken in accordance with 4.4.2. The baseline measurements shall be
performed only once for each trestle. The baseline shall be used for
comparison with similar measurements taken after the tests of 4.4.4 and 4.4.5
to determine the extent of permanent deformation of the trestle, if any.
Evidence of cracked welds or other damage shall be cause for rejection of the
trestle (see 3.5.1).
4.4.4 Off-center loading tests. The following test shall be performed on
each end. in turn, of the trestle saddle. The trestle shall be positioned in
the test machine with the saddle and column fully extended. A load equal to
the trestle's specified capacity shall be applied to the saddle for a time
period of one hour, as depicted in Figure 3. The load shall then be removed
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business