As note earlier, a design choice is almost invariably the result of compromise. Ultimately,
what is sought is an efficient, economical solution, hence whatever the compromise, it
must help achieve this goal.
BREAKING IN A NEW WIRE ROPE
A new wire rope requires carefully installation and close adherence to following all the
appropriate procedures previously noted. After the rope has been installed and the ends
secured in the correct manner, the mechanism should be started carefully and then
permitted to run through a cycle of operation at a very slow speed. During this trial
operation, a very close watch should be kept on all working partssheaves, drums, rollers-to
make certain that the rope runs freely, and without any possible obstructions as it makes
its way through the system. If no problems appear in running the rope, the next step should
include several run-throughs of the normal operational cycle under light load and at
reduced speed. This procedure allows the component parts of the new rope to make a
gradual adjustment to the actual operating conditions.
WIRE ROPE AND OPERATIONS INSPECTION
To assume a high level of safety while keeping the annual cost of wire rope at a reasonably
low level, it is essential to maintain a well-planned program of periodic inspection.
Frequently, there are statutory and/or regulatory agencies whose requirements must be
adhered to, but whether or not these exist in a given locale, the wire rope user can be
guided by the suggested procedures that follow.
Abrasion, bending and crushing represent the ABC’s of wire rope abuse, and it is the
primary goal of good inspection practice to discover such conditions early enough so that
corrections can be made or ropes replaced safely and with minimum effort. When any
degradation indicates a loss of original rope strength, a decision must made quickly as to
allowing the rope to remain in service. But such a decision can only be made by an
experienced inspector. And his determination will be based on:
1. Details of the equipment’s operation: Will the rope break?
2. Frequency of inspection: Will it be safe until the next scheduled inspection?
3. Maintenance history: How rapid is the degradation?
4. Consequences of failure: Will it present hazards to humans?
5. Historical records of similar equipment
To make certain that sufficient information is obtained, following are guidelines that should
be adhered to:
If the fleet angle (Fig. 34) is large, it may be necessary to accept a smaller arc of contact at
the throat; 130° for example instead of 150°. This is done to avoid scrubbing the rope on
the flange of the sheave.
As previously noted, the groove size is evaluated on the basis of how the gage leaf fits the
groove. Daylight under the gage is not tolerable when using the worn groove gage. If a full
over-size gage is used, some daylight may be acceptable, but really must be judged by
relating the measurement to the actual size of the rope.
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