Suspension and safety gear

• Pages: 41-45

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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