Suspension and safety gear

• Pages: 79-81

B5 Suspension and safety gear

B5.1. Type of suspension; number of ropes or chains

B5.l.1. 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); or

roller chains.1

B5.1.2. When the total suspended load (the weight of the car

plus the contract load) exceeds 2201b (100kg), the number of

ropes or chains should not be less than two. The ropes or chains

should be independent of one another.

B5.2. Ratio between pulley or sheave diameter and rope

diameter; safety factor for ropes or chains

B5.2.l. 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.

B5.2.2. When suspension ropes are used, allowance should be

made for a safety factor of not less than 8.

1 It will be recalled that as indicated in 1 (Scope), this code of practice

does not apply to other types of suspension such as by rack and pinion, screw

spindles, etc.

2 The safety factor is the ratio between the breaking load of the suspension

system (obtained by multiplying the number of ropesor legs in the case

of reevingby the guaranteed breaking load * of one rope) and the total

suspended static load of the lift (i.e. the contract load, the weight of the car,

the weight of the ropes over the length of travel, and the possible additional

load of compensation gear, if any).

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