Rope speed up to 100 ft/min; sheave diameter up to 12 in (300 mm). Design based on breaking load of ropes to BS 302 and BS 621 in the 6 x 37 group 100/110 tonf/in^2 tensile strength. Materials and heat treatment, block shell, head fittings, becket, axle pins, sheaves, lubrication, screw threads, locking nuts. Type test at option of purchaser. Proof loading, examination, marking, certificate of test and examination. Table of safe working loads of rigs. Contracts, details to be agreed between purchaser and supplier, requirements for testing machines, care and maintenance.Cross References: BS 302 & 621*BS 408*BS 592*BS 919 *BS 970*BS 1452*BS 1486:Part 1*BS 1610 *BS 1936*BS 2789*BS 2902*BS 3032*BS 3100*BS 3458*BS 3551*