Wire, chains and hoist maintenance

The hoisting mechanism with its wire or chain is the link that directly carries the load up and down. If it wears out or fails, there is no other safety left. Therefore, knowledge of how wire and chains wear out and when they should be discarded is a core competence — not just for the one who performs the legally required main inspection, but also for the crane operator who looks at the equipment every day.

§Wire structure

A steel wire is braided from several threads that are twisted into strands which are twisted around a core — either a steel core or a fiber core. The number of threads, the twist direction and the core type determine how flexible and wear-resistant the wire is. Precisely because the wire is made up of many thin threads it can tolerate some individual threads breaking without the entire wire immediately failing — but the more threads that break, the closer you are to the limit.

§Disposal criteria for wire

Wire is discarded according to fixed criteria, which are among others described in standards for inspection and discard of steel wires for lifting equipment. The criteria are not only about the number of broken wires in one place, but about the overall picture of damage.

• 01A specific number of visible wire breaks within a given length of the wire (the limit tightens over a shorter section).
• 02Reduction of the wire's outer diameter compared to the original – sign of internal wear or corrosion
• 03Deformations such as bird's nest effect (loose, protruding threads), kinks, pinching or frayed ends
• 04Visible corrosion that has attacked the wires, or heat damage from contact with hot surfaces or welding

§Chain wear

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§Lubrication and storage

Wire is regularly lubricated with a suitable lubricant that penetrates between the wires and protects against corrosion and internal wear without making the surface so slippery that friction in pulley blocks becomes incorrect. Chains are kept clean of abrasive dirt that accelerates wear in the joints. Gear not in use is stored dry and hanging so it doesn't lie and create kinks or flattening.

§Brakes and drums

The hoisting gear itself — motor gear drum and brakes — must also be maintained. The brakes must be able to hold the maximum load stationary without slipping and the drum's grooves must guide the wire smoothly up so it does not lie crosswise or jam. Wear or oil on brake surfaces is typically detected when the brake no longer holds the load completely stationary and this is something taken seriously immediately.