30 C.F.R. § 77.1431 Minimum rope strength.
Title 30 - Mineral Resources
At installation, the nominal strength (manufacturer's published catalog strength) of wire ropes used for hoisting shall meet the minimum rope strength values obtained by the following formulas in which “L” equals the maximum suspended rope length in feet: (a) Winding drum ropes (all constructions, including rotation resistant).
For rope lengths less than 3,000 feet: Minimum Value=Static Load×(7.0−0.001L) For rope lengths 3,000 feet or greater: Minimum Value=Static Load×4.0 (b) Friction drum ropes.
For rope lengths less than 4,000 feet: Minimum Value=Static Load×(7.0−0.0005L) For rope lengths 4,000 feet or greater: Minimum Value=Static Load×5.0 (c) Tail ropes (balance ropes).
Minimum Value=Weight of Rope×7.0 [48 FR 53241, Nov. 25, 1983; 48 FR 54975, Dec. 8, 1983]
Title 30: Mineral Resources
PART 77—MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES
Subpart O—Personnel Hoisting
Wire Ropes
§ 77.1431 Minimum rope strength.
