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Prysmian Group recommends using the
following values for the friction factor f as
a guideline for elevator design. Please note
that these are friction factor values f and not
friction coefficient μ.
• Car loading condition
(EN81-50 art. 5.11.2.2.1): f = 0.25
• Emergency braking condition
(EN81-50 art. 5.11.2.2.2): f = 0.25
• Car stalled condition
(EN81-50 art. 5.11.2.2.3): f = 0.75
The values for f given above are based on
laboratory test results. It is mandatory to
perform traction tests during prototyping
of elevator models and for each individual
installation before putting it into operation.
Note that traction of new ropes tends to
increase during the first elevator movements.
Please note that the main concern of the
EN81-20 art. 5.5.3.b condition for emergency
stops is to ensure sufficient deceleration.
Elastomer coated elevator ropes have
significantly higher friction factors compared
to bare steel wire ropes. In some cases, this
can lead to very high decelerations during
emergency stops.
We recommend to use a wrapping angle of
at least 120° for the traction sheave. Please
contact your rope supplier in case your elevator
design requires wrapping angles less than 120°.
The electrically-isolating nature of the coating
can cause electrostatic charging during
elevator usage. Electrical grounding of the
steel rope core is recommended, particularly if
plastic deflection sheaves are used.
Usage and maintenance
FRICTION FACTORS
30° ≤ y ≤ 60°
Ø 6,5 mm
Surface roughness
Ra = 1,6 µm
Groove radius
3,3 mm ≤ r ≤ 3,6 mm
