No matter the size of the crane you are using, whether it is a 1-ton jib crane or a 20-ton bridge crane, proper care of the wire rope is of utmost importance to longevity of operation and worker safety. One aspect of caring for wire rope is lubrication of the cable and all its individual strands. Failure to keep the wire rope well lubricated can be costly in terms of dollars by requiring premature replacement, and if a wire rope snaps due to lubrication deficiencies, serious injury or death could be the result for anyone standing nearby. Below are three consequences that can occur as a direct result of poor wire-rope lubrication as well as a quick way to check to see whether proper lubrication is in place.
Internal and external friction wear
One of the most important functions of lubrication is to minimize friction when the wire rope is in use. Internal strands rub against one another, and proper lubrication prevents this from occurring. Another type of friction that is damaging to wire rope is external wear; the crown of the rope is exposed to friction as it rubs against the internal channel of pulleys, and this can also be minimized with lubrication. Keep in mind that some friction is desirable, as too much lubrication can cause slippage or loosen the intertwined strands. However, in most cases, the greater likelihood between too little and too much lubrication is that not enough lubrication will be applied as needed.
A sign that friction wear is occurring is rouging, which is the flecking of tiny bits of steel from the wire and subsequent oxidation of each. If you notice a powdery, rusty residue on the exterior of the wire rope in use, suspect that internal friction is causing damage to the strands and that inspection of the wire rope will be necessary to check the rope's suitability for continued use.
Internal corrosion of strands
Another function of lubrication with wire rope is to prevent corrosion of the internal strands. Lubricants form a barrier to keep out moisture, but once the lubricants dry out, expect a rapid deterioration of the strands due to water intrusion and oxidation. This problem is especially accelerated in marine environments and other areas where high humidity is prevalent.
If you are using a crane in a susceptible environment, then you will need to be on guard against lubricant desiccation. Coupled with frictional wear, corrosion of the strands of wire will drastically reduce the lifespan of the rope. That is why inspection and lubrication are important functions, and such efforts should be elevated in importance whenever wire rope is handled in damp environments.
Wear of pulleys
Though it may be secondary damage, the failure to keep wire ropes lubricated can also cause permanent damage to the crane pulleys. Wire rope shrinks in diameter as the lubricants evaporate or are washed out. This shrinkage causes wire rope to slip deeper into the grooves of the pulleys, and this action generates increased frictional wear against the interior of the pulleys. The result is a malfunctioning crane that may not hoist properly, and replacement of the pulleys is the only option left as a result of a failure to maintain equipment. Such replacements are costly and take equipment out of service as well.
Checking for adequate lubrication
A simple field test to check for proper lubrication of wire rope can be performed quickly and on a daily basis before using equipment. To test for adequate lubrication, swipe your fingertips across the wire rope at a moderate rate. If the wire rope is poorly lubricated, your fingertips will remain dry and clean. Should the wire rope be somewhat lubricated, but insufficiently, then you should be able to view an oily film on your fingers but not not be able to feel it. Finally, if the wire rope is well-lubricated, then you will be able to both see the sheen and feel the lubricant on your fingers. Immediately suspend use of any equipment if the rope is not properly lubricated for the purposes of inspection or lubrication.
Talk to a company like A C Jones Trucking Inc for more tips.
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