For new rope, extra caution should be observed as to its fit in the groove.
Characteristically, ropes become smaller in diameter immediately after being placed in
service. As a result, they would operated satisfactorily in a “worn” groove; one that was
gage OK by the “worn” groove gage. Nonetheless, in some cases, a rope may not “pull
down,” and it this happens, abnormal wear may occur.
It is important to remember that a tight groove not only pinches and damages the rope but
that the inching prevents the necessary adjustment of the wires ann strands. On the other
hand, a groove that is too large will not provide sufficient support; in this case, the rope will
flatten and thereby restrict the free sliding action of the wires and strands.
The size of the groove is not only critical item to be examined closely. The condition of the
groove is also an important factor of concern. Is it smooth or imprinted? If the groove is
imprinted then it must be re-machined or, if it is imprinted too deeply, it means that sheave,
roller or drum must be replaced. If replacement is indicated, a larger sheave or drum should
be installed if possible, or a harder material should be specified for the replacement.
Groove examination should also concern itself with how the groove is wearing. If it is worn
off-center, thereby forcing the rope to undercut or to rub against the flange, it then
becomes necessary to correct the alignment of the reeving system, and to specify a harder
material.
When checking the grooves, the bearings of the sheaves and rollers should also be
examined. They should turn easily. If not, each bearing must be properly lubricated.
“Wobble” in the sheave-from broken or worn bearings-is not acceptable. Bad bearings will
set up vibrations in the wire rope that can cause rapid deterioration unless the condition is
remedied. Bad bearings also increase the force on the rope that is needed to move a given
load, since friction forces will e greatly increase.
Sheaves with broken flanges may allow the rope to jump from the sheave and become
fouled in the machinery. When this happens, the rope is cut, curled, and the crowns of the
wires in the strands are burred. There is ample evidence to support the rule that sheaves
with broken flanges must be replaced immediately.
A sheave or drum with a flat spot can induce a “whip” into the line. This whip, or wave,
travels until is stopped by the end terminal, at which point the rope may bend severely. This
condition helps to accelerate the fatigue breakage of wires. Sometimes the reeving is such
that the whip or wave is arrested by a sheave, or the drum itself. In these circumstances,
the whipping will cause wire breaks along the crowns of the strands. Obviously sheaves or
drums that excite vibrations of this sort, must be repaired or replaced.
GUIDELINE TO INSPECTIONS AND REPORTS FOR EQUIPMENT, WIRE ROPE
AND WIRE ROPE SLINGS
1. Maintain all inspection records and reports for the length of time deemed appropriate.
2. Prior to each daily use, the following procedure should be followed.
a. Check all equipment functions.
b. Lower load blocks and check hooks for deformation or cracks.
RT500
Applicable Standards / Regulations
314 REVISED:
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