Section 7.152. Machines and sheaves

(a) Winding drums, traction sheaves and overhead and deflecting sheaves shall be of cast iron or steel, of a diameter not less than 30 times the diameter of the wire hoist ropes. The rope grooves shall be machined. Where eight by 19 plow steel ropes are used, the diameter of drums and sheaves may be reduced to 20 times the diameter of the rope.

(b) The factor of safety based on the static load, that is, the contract load plus the weight of car, ropes, counterweights, and the like, to be used in the design of personal service elevator hoisting machines shall not be less than eight for wrought iron and steel, and ten for cast iron, cast steel, or other material.

(c) Set-screw fastenings shall not be used in lieu of keys or pins at a connection subject to torque or tension.

(d) No friction gearing or clutch mechanism shall be used for connecting the hoist drum or sheaves to the main driving gear.

(e) Gearing having cast iron teeth shall not be used.

(f) Electric elevator machines shall be equipped with electrically-released, spring-applied brakes.

(g) No single ground, short circuit, counter-voltage or motor field discharge shall prevent the brake magnet from allowing the brake to set in the intended manner during normal operation.

(h) An electric elevator machine shall be arranged for manual operation by crank in case of power failure, and a suitable crank shall be provided and kept near the machine.