OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 21 Rigging

Section 302 Matching components

Subsections 302(1) and 302(2)

Unless otherwise specified by the manufacturer, the diameter of winding drums should not be less than 20 times the diameter of the rope. This will reduce the likelihood of weakened rope caused by excessive bending stresses.

Subsection 302(3)

Wire rope can be damaged if the angle and width of the sheave groove is incorrect for that wire rope. Too narrow a groove will pinch and bind the rope, causing excessive abrasion and fatigue leading to shortened rope life (see Table 21.2). A groove that is too wide will not properly support and guide the rope, causing the rope to flatten (see Figure 21.21).

Figure 21.21 Example of a sheave providing a proper arc of support to a rope

The condition and contour of sheave grooves have a major influence on rope life. The grooves must be smooth and slightly larger than the rope to prevent the rope from being pinched or jammed in a groove. The bottom of the groove should have an arc of support of at least 120 to 150 degrees and the sides of the groove should be tangent to the arc.

The depth of a sheave groove should be at least 1.5 times the rope’s diameter and the tapered side walls of the groove should not make an angle of more than 18 degrees from the centre line.

Table 21.2 Example of manufacturer’s specifications matching wire rope diameter with sheave characteristics

Subsection 302(4)

Figures 21.22, 21.23 and 21.24 show examples of end fittings.

Figure 21.22 Example of socketing operation

Figure 21.23 Example of swaged sockets

Figure 21.24 Examples of wedge socket

Subsection 302(5)

Figure 21.25 shows a sheave with cable keepers, dividers and shell (guard) in place. Combined, the keepers, dividers and shell prevent wire rope from leaving the sheave groove and must not be removed except for maintenance, inspection or adjustment, and then immediately replaced.

Figure 21.25 Example of a sheave with dividers and shell in place