WP6-Brochure-E4 brochure - ELA European Lift Association.

ends to have a smaller radius. Furthermore, they do not require lubrication throughout their
lifetime, which is an important ecological advantage, besides saving maintenance costs.
The weight of the ropes is becoming an increasingly important concern as building heights
increase at a fast pace. Rope weight increases rather exponentially with height and can reach
50 to 70 tons to move just a few passengers in a high‐rise building [14].
Figure 3‐29. Cross section of the SchindlerAramid ropes (source: Schindler)
Aramid ropes are very costly and some manufacturers have now started to use traction belts
instead of ropes. These belts consist of a band of ultra‐thin steel cables encapsulated in a
polyurethane sheath. These new belts are approximately 20% stronger, do not require
maintenance lubrication, and can reach twice the life‐time of the standard steel ropes.
Figure 3‐30. Otis GEN2 polyurethane flat belt (Source: Otis).
The higher bending capabilities of both aramid ropes and polyurethane belts make possible
the use of a smaller traction sheave which results in a smaller torque requirement and the use
of a smaller motor.
For example, flat belts allow the use of a 100 mm diameter sheave instead of the commonly
used 720 mm diameter sheave. This way, at a given lift speed, the smaller sheave rotates 7,5
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