MIL-T-14521E
7.4.4.1 Welding. Welding shall be neat in appearance and shall be strong
enough to withstand application of the proof load and off-center rated loads to
the completed trestle without cracking, or other damage.
3.4.5 Painting. All surfaces of the trestles. inside and out, shall be
painted in accordance with the best practice of the commercials jack and vehicle
support stand industry. Dried paint shall net interfere with the free movement
of the pawl.
3.5 Product performance characteristics. The trestles shall be capable of
supporting the proof load and off-center rated load in all height positions
from fully lowered to fully extended with no failure or permanent deformation
exceeding that specified in 3.5.4.
3.5.1 Preload. At the contractors option. a preload not exceeding fifty
percent of the rated load may be applied as depicted in Figure 1 , to settle the
trestle in its load carrying configuration, remove looseness and allow for
minor permanent set and peening of metal parts. The preload, if elected. shall
be applied prior to any measurements or testing. The preload shall be applied
only once at the fully extended position and only once at the fully lowered
position and nowhere in between.
3.5.2 Off-center load. The trestles shall not become unstable when
subjected to the rated load capacity, applied by a universal compression
testing machine, on one lip of the saddle and then on the other lip
(see Figure 3) at any and all positions from fully lowered to fully extended.
The trestles shall evidence no sign of column bending, visible cracks,
component failure lure or permanent deformation exceeding that specified in 3.5.4
after being loaded on each lip of the saddle.
3.5.3 Proof load. The proof load shall be 1.5 times the rated load
With the proof load applied by a universal compression testing
capacity.
machine on both lips of the saddle (see Figure 4) , the trestle shall sustain
the proof load at any and all positions from fully lowered to fully extended,
with no permanent deformation exceeding that specified in 3.5.4. no cracked
welds, no mechanical failure, and no component damage.
3.5.4 Deformation. Permanent deformation of the trestles after any and
all load tests shall not exceed
inches in the trestle base length and
saddle height, dimensions A and B of Figure 2. when compared with the base line
measurements.
3.6 Component parts. The trestles shall consist of a base, a one piece
column and saddle with rack, a pawl, a handle and any other components needed
to effect an adequate design for the intended purpose.
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