How to define the minimum number of suspension ropes in Elevators

The number of suspension ropes in elevators application, is calculated based on the safety factor value with the formula reported in EN 81-50:2022. This formula does take into consideration the elevator configuration, but not the specific pressure between ropes and traction grooves.

The recently published technical rule for elevator’s wire ropes (ISO 4344:2022) has

introduced suspension ropes with increased tensile and MBL. Furthermore, the new MRL elevators are leaning toward reduced diameter ropes and D/d<40. The specific pressure is getting to even higher values.

Even if not required by EN 81-50, it would be worth to reintroduce the calculation of the

specific pressure as a good practice. Besides that, it would make sense to provide guideline on how to correct installation issues that are causing shortened rope lifetime instead of identifying only the discard criteria as per ISO 4344 AnnexG.

Author(s): N. Imbimbo