Okla. Stat. tit. 45, § 45-512: Safety equipment for shafts

The operator or superintendent shall provide and maintain from

the top to bottom of every shaft, where persons are raised or

lowered, a metal tube suitably adapted to the free passage of sound

through which conversation may be held between persons at the top

and bottom of said shaft, and also a means of signaling from the top

to the bottom thereof, and shall provide every cage or gear carriage

used for the hoisting or lowering of persons with a sufficient

overhead covering to protect those persons when using the same and

shall provide also for each said cage or carriage a safety catch

approved by the mine inspector, and the said operator or

superintendent shall see that flanges with clearance of not less

than four (4) inches when the whole of the rope is wound around the

drum, are attached to the sides of the drum of every machine that is

used for lowering persons into or hoisting them out of the mines,

and also, that adjacent brakes are attached to the drums: Provided,

that the rope shall be left around the drum at least two and one-

half (2 1/2) times when the cage is at the bottom. At all shafts,

safety gates to be approved by the mine inspector of the district,

shall be so placed as to prevent persons from falling into the

shaft.