GRAVITY GOODS ROPEWAY
9.2 Components Needing Special Care
9.2.1 Wire ropes
a) Inspection of wire ropes
Wire ropes in use should be inspected on a
regular basis. There is a high stake involved
with equipment and human lives if the periodic
inspection of ropes is ignored. Wire rope must
be replaced before there is any risk of failure.
A rope broken in service can destroy machinery,
curtail production or threaten health and life of
an operator.
The purpose of inspection is to accurately estimate
the service life and strength remaining in a rope
so that maximum service can be taken within
the limits of safety allowed by design. Results of
the inspection should be recorded to provide a
history of rope performance on a particular job.
The person assigned to inspect the wire ropes
should have good and thorough knowledge of wire
ropes and their operations. Inspections should be
made regularly and the results properly recorded.
When inspecting the rope, the condition of the
anchorage posts, sheaves, rope clamps and other
end fittings should be noted. The condition of
these parts affects rope wear and tear therefore,
any defects detected must be repaired on time.
The operator is the most reliable person to give
factual information about the condition of the
ropes as he/she is the one who observes each
operation. In case of any accident involving the
ropes, the operator should immediately suspend
the operation and report to the concerned
management committee/authority. The wire
ropes must then be thoroughly inspected by a
competent person either for repair, maintenance
or replacement depending upon the degree of
its wear and tear. Normally, the ropes must be
inspected once in three years for the following:
Loosening of wires or the strands
The amount of wear showing on the
surface of the rope, which shall not
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exceed one third of the original diameter
of outside individual wire
The degree of corrosion present in the
rope or the number of broken ropes
The condition of splices in the ropes and
Extension of a rope lay, averaged from a
minimum of 10 lays
Simple visual observation of the rope is not
enough. The inspector needs to check on cross
sectional dimensions of ropes at various intervals
to check on the extent of wear and tear. By this
the inspector can quickly determine where the
rope is rubbing or contacting with other ropeway
accessories.
b) Rope replacement
The rope is to be replaced under any of the
following conditions:
The diameter of the rope has been reduced
by 10 per cent of its original diameter at
the time of installation;
The number of broken wires in any stretch
of the rope length equals to 30 times the
diameter of the rope and exceeds 10 per
cent of the total number of wires in the
wire rope;
Estimated loss of strength is 20 per cent
of the breaking strength of the wire rope
for any reason;
Excessive wear and tear on outer wires
which has reduced their diameters (in
radial direction) by approximately 20 to
30 per cent;
Wires becoming loose;
Distortion of the rope;