Pulley blocks for fibre ropes

• Pages: 89-90

12. Pulley blocks for fibre ropes

12.1. General provisions

12.1.1. (1) A pulley block for use with rope consisting of man-

made or natural fibre should have either a cast housing, or side and

partition plates and straps of steel or of wood suitably reinforced

with steel or aluminium straps.

(2) Except in the case of a cast housing, the side. straps should be

adequately and properly secured to the head fitting.

12.1.2. (1) The diameter of the sheave(s) measured at the

bottom of the groove should not be less than 5.5 times the rope

diameter it is designed for.

(2) The rope groove should have a depth of not less than a third

of the diameter of the rope, the radius of the groove being not less

than 1 mm greater than half the diameter of the rope.

12.1.3. As a general rule, the block should not be fitted with

more than three sheaves and a becket, or four sheaves if the block is

without a becket.

12.1.4. Provision should be made for the lubrication of all

metal bearings and swivel head fittings and, where necessary, any

plastic bearings.

12.2. Safe working load

12.2.1. The safe working load of the block should be assessed

on the basis of use with best-grade manila rope.

12.3. Compliance with other requirements

12.3.1. The block should comply with the requirements of sub-

paragraphs 4.2.1(e), 6.4.5(d), and 6.4.7(1) and (2), and as far as

possible with section 6.5.

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