One of the smallest, but still the most important, components of any lifting or hoisting apparatus is wire rope. From wire rope hoists and winches of gantry systems to the running rigging of a jib crane and everything in between, wire rope plays an integral role. More often than not, however, wire rope is the most overlooked and inspected component on a jobsite. Operators will check the Safe Working Load tag of a shackle or inspect a sling before use, all the while, the wire rope that hoists the load for every single lift cycle is often unchecked.
To understand some of the reasons behind this phenomenon, let us look at some construction aspects. Wire rope consists of multiple individual wires that are arranged in groups, or strands, and further arranged around a central core of either fiber or steel. The construction and configuration explains how much the rope will crush under a load and how stiff it is to bend. A steel core offers more crushing resistance on a multi chambered drum, while a fiber core allows for increased flexibility to accommodate smaller bend radii. Wire rope failures are typically the result of an incorrect specification at the onset of design and should be left to the equipment provider to decide rather than what is available in the stock on the lot.
Failure of duty of care often happens during the inspection phase. As outlined in LOLER, ‘thorough examination’ from a ‘competent’ person must be carried out on lifting equipment on a regular basis. However, wire rope must not be overlooked and in addition to the required formal checks, must also undergo visual checks. One thing to look out for during visual checks for wire rope is broken wires, especially if they are found grouped together over a short distance, indicating a fatigue failure rather than a single break. Most wire rope fatigue failures are seen on the hoist sheave. Also, check for corrosion. A reduction in diameter may indicate a serious failure, as rope made to a certain diameter specifications may conceal internal damage. Rope must be immediately removed from service if kinking, birdcaging, or flattening is evident.
Matching wire rope to each specific application is critical. A winch or hoist OEM specs a diameter, construction, and a breaking load for a reason. Adjusting these specifications by substituting a rope that more closely aligns with your budget but isn’t recommended increases risk accordingly and with no added cost savings.
There are some basic protective measures that enhance the lifespan of your rope. These include correct drum coiling, avoiding sharp bends, and regular lubrication. Lubrication actually gets to the heart of the rope and protects the internal wire from corrosion and reduces the friction as the strands glide against one another under constant tension, even during routine lifts. For hoisting and winching systems run daily by businesses, an easy lubrication routine tied to the already existing maintenance schedule lowers the cost of rope replacement and eliminates the negative impact of downtime.
When purchasing, the procurement and facilities teams would benefit from working with a wire rope supplier that specialises in construction, diameter, and certification. This ensures the new rope will not be a costly mistake in the future. Wire rope is a consumable, and treating it as such with scheduled maintenance and checks along with the correct selection and protective measures ensures the equipment stays operational.