MIL-C-53057(ME)
pitch diameter shall be not less than recommended by SAE J881 for the
wire rope furnished with the winches.
3.13.4.1 Powered load lowering. The main and the auxiliary load
hoist drums shall be equipped with a powered reversing drive, and
suitable control features to provide precision controlled power
lowering of loads. The powered load lowering mechanism shall be
capable of lowering the loads at a smooth, controlled rate of speed,
dependent on engine speed, without jerking, bouncing or slipping the
load. A braking device may be used to assist the power lowering
mechanism. The winch shall not be capable of free fall.
3.13.5 Wire rope. The crane shall be provided with sufficient rope
for both the main and auxiliary systems so that when the boom is
fully extended at its maximum boom angle, reeved for maximum part
lines and the hooks at ground eleva ion, there shall be not less than
t
one complete layer of rope on the hoist drum. The wire ropes shall be
in accordance with RR-W-410, type I, class 2, 6 x 19, construction 3
or 4, IWRC improved plow steel uncoated, preformed, regular lay. The
wire ropes shall have safety factors not less than recommended by SAE
J959.
3.13.6 Boom angle and boom length indicators A boom angle
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indicator shall be provided which shows angular elevation of the boom
and conforms to SAE J375. The boom angle indicator shall be visible
to the operator in his normal seated position. A boom length
indicator shall also be provided in increments to match with the load
capacity chart in accordance with SAE J1180.
3.13.7 Load indicating and warning device A load indicating and
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warning device of the load-moment type shall be provided to perform
the following functions while on outriggers:
a. Provide a dial or digital reading of hook load in pounds.
b. Provide a dial or digital reading oŁ load rating in feet.
c. Provide a dial or digital reading of load moment as a percentage
of rated capacity.
d. Provide visual warning (amber light) when load moment reaches 85
-
percent of rated capacity, visual and audible (red light and
alarm) warning at a 95 percent rated capacity, and control lock
out for boom lowering and extension at 100 percent rated
capacity.
The device shall provide for manual selection of parts of line. The
device shall conform to SAE J159, J375, and J376.
3.13.8 Lift and extension mechanism The crane shall be capable of
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accomplishing hoist and boom extension both simultaneously and
independently. Control valves or other positive means shall be
provided to prevent cavitation in the lifting/lowering cylinders and
the extension/retraction cylinder(s) when tested in accordance with
4.6.2.4 and 4.6.2.38.
3.14 Outriggers. Four independently hydraulically operated
outriggers, capable of extension to not less than 7 inches below
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