Current through Register Vol. 54, No. 50, December 14, 2024
Section 7.192 - 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. When 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 these 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 eleavtor machines shall be equipped with electrically-released, spring-applied brakes which apply automatically if the operating device or stopping contacts are in the stop position.(g) No single ground, short circuit, countervoltage, or motor field discharge shall prevent the brake magnet from allowing the brake to set if the operating device or stopping contacts are in the stop position.(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.