and minimum drum diameters.
Winding drums and overhead deflecting
sheaves shall be of cast iron or steel, of a diameter not less than thirty (30)
times the diameter of the hoisting ropes. The rope groves shall be machined.
Exception: Where eight by nineteen (8 ×19)
steel ropes and seven by nineteen (7 ×19) aircraft cable are used, the
diameter of drum and sheaves may be reduced to twenty-one (21) times the
diameter of the rope or cable.
Factor of safety.
of safety, based on the static load (the rated load plus the weight of the car,
ropes, counter-weights, etc.) to be used in the design of driving machines and
sheaves shall be not less than:
(1) Eight (8)
for wrought iron and steel:
(10) for cast iron, cast steel and other material.
Set-screw fastenings shall not be used in lieu of keys or pins if the
connection is subject to torque or tension.
Friction-gearing, clutch mechanism,
or coupling. Friction-gearing, clutch mechanisms, or couplings shall not
be used in connecting the drum or sheaves to the main drying gear.
Use of cast iron in gears.
Worm gearing having cast iron teeth shall not be used.
Driving machine brake.
Driving machines shall be equipped with electrically released spring-applied
brake. A single ground or short circuit, a counter-voltage or a motor
field discharge shall not prevent the brake magnet from allowing the brake to
set when the operating device is placed in the stop position.