MIL-HDBK-1038
j)
For custom design (built-up) hoists, the wire rope drum and sheave
groove depths are required to be 0.438 and 1.150 times the wire rope diameter,
respectively.
k)
Custom designed (built-up) hoists with double reeving must use and
equalizer bar (rather than an equalizer sheave) for balancing wire rope pulls.
l)
Custom designed (built-up) hoists of OET, cantilever, gantry, and
semi-gantry cranes are required to have two electro-mechanical hoist brakes, each
with a minimum rating of 130 percent of the rated motor torque.
m)
Cranes utilizing standard commercial (packaged) hoists or
hoist/trolley units, are required to have two hoist brakes, each with a minimum
rating of 130 percent of the rated motor torque. Both hoist brakes may be
electro-mechanical, or one may be electro-mechanical and the other a mechanical
load brake. (Either Weston or roller/incline types of mechanical load brakes are
acceptable.)
n)
Portal, floating, and other cranes with operator's cabs on the same
structure as the hoist, require two electro-mechanical brakes (shoe, disc, band,
or caliper type) in the hoist drive even when a foot operated hydraulic hoist
brake is present for speed modulation. (The shoe type electro-mechanical brake
and the hydraulic brake may be integral or separate units.)
o)
Hoists on all cranes that handle nuclear fuel, and on all bridge
cranes with rated capacities of 10 tons or less, are required to have one of their
two hoist brakes (or brake sets) act directly on the wire rope drum. Single or
multiple caliper disc brakes are to be applied to one or two discs bolted or
welded to the drum barrel. Band brakes are to be applied to the drum barrel.
p)
All drive components of custom designed (built-up) hoists those
that transmit the driving torque, braking torque, and their supports/housings
are required to be steel. Exceptions are permitted for gear reducer housings and
brake wheels and discs, which may be of ductile cast iron; and electric motor
housings, which may be ductile cast iron or aluminum. These ductile cast iron and
cast aluminum components must have a minimum elongation of 5 percent in 2.00
inches.
q)
Standard commercial hoists and hoist/trolley units, whose use cannot
be avoided because of site-specific constraints, must be selected to comply with
the requirements of item (p), above, to the maximum practical extent. (It is
considered practical to replace certain components and assemblies, such as wire
ropes and load blocks, with their higher grade or custom designed steel
counterparts.)
r)
Components and assemblies of cantilever, gantry, and semi-gantry
cranes that correspond to those described above, must comply with those
requirements.
s)
Cab operated cranes are required to be equipped with "deadman"
controls; or alternatively, with a seat for a back-up operator.
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