Suspension and safety gear

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A5 Suspension and safety gear
A5.1. Type of suspension; number of ropes or chains
A5.1.l. Cars and counterweights should be suspended by
round strand steel wire ropes, the wires of a strand to be wound
in parallel lay (linear contact between wires).
A5.1.2. For traction drive machines the number of ropes
should not be less than two. The ropes should be independent
of one another.
A5.1.3. For drum drive machines the number of ropes
should not be less than two for the car and two for the counter-
weight, if any. The ropes should be independent of one another.
A5.1.4. Where reeving is used (e.g. 2 to 1 or more roping)
the number of independent ropes should not be less than two.
Exception
The use of roller chains may be permitted for chain speeds not
exceeding looft per minute (O.50m/s).
In that case the number of chains should not be less than two.
The chains should be independent of one another.
A5.2. Ratio between pulley or sheave diameter and rope
diameter; safety factor for ropes or chains
A5.2. 1. The pulley or sheave diameter should not be less than
40 times the diameter of the suspension rope, whatever the number
of strands in each rope.
A5.2.2. When three or more suspension ropes are used allow-
ance should be made for a safety factor1 of not less than 12.
The safety factor is the ratio between the breaking load of the suspension
system (obtained by multiplying the number of ropesor of legs in the case
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