Liebherr has extended the overall service life of its Fibre ropes for tower cranes from 14 to 16 years, following the results of multi-year trials and field data analysis.
The manufacturer has also increased the maximum permitted period of use for these ropes to up to 12 years.
The updated service intervals apply automatically to all new ropes as well as those currently in the field, regardless of their production date. This decision follows a series of ageing trials conducted over several years.
The trials exposed the Fibre ropes to different weather conditions at multiple international sites for intervals of two, four, and six years.
After exposure, the ropes were tested under realistic conditions until failure.
According to the company, they demonstrated performance levels almost equivalent to new ropes even after six years of exposure.
At the same time Liebherr reviewed the operational usage of Fibre ropes on cranes in real construction environments.
The increased service life is intended to allow a longer period of use without extending storage time which can particularly benefit cranes where ropes experience less intensive use.
Liebherr’s evaluation of field data from the past seven years indicates that at least half of all cranes using Fibre ropes could see notable benefits from this change, though the actual advantage depends on how much stress each rope endures over time.
When comparing Fibre ropes to traditional steel ropes, Liebherr reports that most steel ropes are replaced after two to 2.5 years on cranes, based on analysis of almost 200 machines in its rental fleets over up to 13 years.
The company notes that steel ropes are often removed before reaching their maximum theoretical lifespan due to rope damage.
In contrast, Fibre ropes can reportedly be repaired directly on the crane, reducing the need for replacements and minimising downtime.
Liebherr states that around 90% of Fibre rope damage incidents can be resolved with repairs or rope shortening, allowing most ropes to remain in service until their discard criteria are met.
The rope’s overall service life continues to be counted from its original manufacture date, which is engraved at the end connection.
If a Fibre rope should reach its discard criterion earlier, this will be indicated by a visible red layer, as before.
According to Liebherr, more than 400 Fibre cranes are expected to be in operation by the end of the year.
Liebherr Tower Crane Division fibre technology product manager Jochen Huber said: “We are convinced that the technology will prevail in the market thanks to its economic advantages.”
