MIL-T-14521E
3.6.1 Base. The trestle base shall have four legs forming a pyramid
The trestle shall be supported by
configuration symmetrical about the column.
the bottom of the legs only. No pads or supporting plates shall be used on the
bottom of the legs. The length and width of the base shall meet the
requirements of ASME/ANSI PALD-4. The base shall afford a sturdy structure for
the distribution of the supported load. The upper portion of the base, called
the collar, shall position and retain the column and saddle and shall not
deform under proof load or off-center loading.
3.6.2 Column and saddle. The column and saddle shall support the load and
transfer teh force through the collar to the trestle base. The saddle is the
load contacting and bearing part of the column and shall provide safe retention
of frame members, under carriage, lower control arms, cross members, spring
mountings and shackles, axle and axle housings of vehicles. The saddle height
shall be adjustable in increments of not more than 1.5 inches from fully
lowered to fully extended. Retention lips at the ends of the saddle shall be
inch high on the inside dimension. The column and saddle shall
at least
be integrated as a -
single piece casting or forging and shall have the rack
machined, cast, or forged into the column, The rack shall meet the
requirements of 3.6.3.
The trestle shall be designed such that the bottom end
of the column shall not come closer than
inch to the tester platen when
subjected to the proof load with the column in the lowest possible position.
Outside saddle dimensions shall be as specified in Table i. The design of the
trestle shall prevent separation of the column and saddle from the base when
the trestle is lifted by the column or saddle.
3.6.3 Rack and pawl . The configuration of the rack and pawl shall be such
that the pawl engages the rack at every tooth by action of gravity alone as the
rack is raised past the pawl.
The pawl shall be integral with the handle and
shall utilize the weight of the handle to engage the pawl with the teeth of the
rat} . The trestle shall contain no springs or other devices to cause the pawl
to engage the rack , or to augment the force imparted by gravity. Deliberate
action by the operator shall be required for rack and pawl disengagement, in
addition. the teeth of the rack shall be designed to interlock with the pawl as
a load is applied from above, so that the pawl cannot be disengaged from the
rack without removing the load and raising the saddle slightly.
The wear of
the rack and pawl shall be self compensating.
3.6.4 Handle. A handle shall be provided that shall accommodate
one-handed lifting and carrying of the trestle for movement around a shop.
3.7 Identification marking. Trestles shall be permanently marked in
accordance with
including the National Stock Number, contract
number , manufacturer `s name. nomenclature and load capacity.
In addition, the
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