LIFTING ATTACHMENTS
Widths of Transweb’s polyester (Left) and HMPE (Right) slings for comparison.
by corroded or broken wires; kinks induced by poor storage can also weaken them. This makes thorough expert inspection even more critical. A damaged wire rope sling cannot be repaired but must be discarded immediately. Maintenance costs for wire rope slings can be higher due to this need for more frequent inspections; they may also need lubrication. Both chain and wire share one significant disadvantage: they can be damaged by rubbing against corners of the load, but by the same token they can damage the load at such sites. Here synthetic slings come into their own. Again manufacturers are many: Slingmax, Lift- All and Cortland in the US, and in the UK Slingco, are some. Synthetic slings were originally made of polyester – and are still widely available in that material – and are economical and non-abrasive, which is ideal for delicate loads, and have a slight stretch to them to help absorb the impact of shock loads. They come in various shapes and forms, of which the web sling is perhaps the most common; the polyester web is accessible, is affordable and for general lifting applications where ease of replacement and broad availability are key considerations it has few drawbacks. Web slings are available in widths ranging from 2.5cm 1 inch up to 30cm and more, and WLL of over 50t. Their flatness makes them easy to transport – you can simply roll them up, in which form they take up very little space; more importantly the flat surface helps distribute the stress on the load. The shape does though come with a disadvantage: it leaves more of the polyester fibres exposed to the air and to ultraviolet light, which degrades them in ways that may not be immediately obvious to visual inspection.
Rounding things up A work-around is the polyester roundsling. As the name suggests the profile is round not flat; the fibres are bundled together and enclosed in a woven sleeve which protects them from light and from abrasion. The whole sling is in the form of an endless loop, which
A polyester webbing sling, from Transweb of Oldham.
is hitched around the load, frequently in what boy scouts might recognise as a larkshead knot; the loose end goes over the hook. It is generally an easy operation to perform. A further advantage is that, being a loop, any point of it can be positioned at the top so stress points can be concentrated at a different place for each lift, so spreading the wear evenly to all parts of the sling. The protective cover improves resistance to abrasion and helps shield the core fibres from UV light. It does not, however, eliminate all environmental effects, particularly when slings are stored or used in prolonged outdoor conditions. Even so, polyester remains widely used because it is cost-effective and performs reliably in light to moderate lifting applications. However, in recent years a revolution has occurred: the arrival of HMPE, which stands for High Modulus
32 | July/August 2026 |
www.hoistmagazine.com
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