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
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
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).