2.24.3 Factor of Safety for Driving Machines, Sheaves, and Drums
(a) 8 for metals having an elongation of at least 14% in a gauge length of 50 mm (2 in.) when tested in accordance with ASTM E8.
(b) 10 for cast iron or for metals having an elongation of less than 14% in a gauge length of 50 mm (2 in.) when tested in accordance with ASTM E8.
(c) 10 for sheaves of plastic, fiber-reinforced plastic, or combinations thereof. The material used shall ensure that the factor of safety is not less than 8 during the service life of the sheave.
The load to be used in determining the factor of safety shall be the resultant of the maximum tensions in the suspension means leading from the sheave or drum with the elevator at rest and with the rated load in the car.
Driving-machine components including bedplate, where used, subject to forces due to the application of the emergency brake (see 2.19.4) shall be designed to withstand the maximum forces developed during the retardation phase of emergency braking so that the factor of safety resulting from the emergency braking and all other loading acting simultaneously, if applicable, shall be not less than specified in 2.24.3(a) and 2.24.3(b).