STABILITY/ STRUCTURAL STRENGTH
Crane load ratings with an asterisk (*) beside them are
based on the machine’s structural strength. All other
ratings are based on stability. Therefore, when lifting in
an area where the rated load is governed by strength,
an overload can produce an abrupt failure. This may
be in the boom, outrigger beam, or elsewhere. For ex-
ample, this is particularly true when the operator does
not know the weight of the lifted load or fails to account
for the forces necessary to unstick a load from the mud
or the extra ice, snow, mud, etc. on the load.
In the stability zone, some operators attempt to deter-
mine if the crane can lift the load by allowing the crane
to tip. This can result in a tip over, particularly if the
boom point moves out to a greater radius than the load
centerline, which it tends to do due to boom deflection
and machine tipping. In this condition, when the load
comes free of the ground, it swings out rapidly, endan-
gering workmen and can pull the crane into a tip over
condition. Also, if the load is heavy enough and will not
move and the boom point moves out far enough, the
rating can change back to structural with the associat-
ed abrupt failure discussed above
.
Therefore: CAUTION - Do not attempt to tip the ma-
chine to determine allowable load.
MAXIMUM PERMISSIBLE HOIST LINE LOAD
By lifting with the boom or telescope cylinders, the
crane can easily exceed the rated capacity of the wire
rope and even the breaking strength of the wire rope.
It is mandatory that wire rope utilized on the crane
have adequate breaking strength as rated by the rope
manufacturer, be in good condition, and proper num-
ber of parts of line be used. See Page 4-32 for mainte-
nance and inspection and consult PCSA Std. No.4 and
ANSI Standard B30.5 and the wire rope users manual.
OPERATING PROCEDURES
Revised: October 20053 - 29RT700
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