Fig. 3. Deflection angle between drum and sheave.
l On grooved drums, the drum pitch can be measured by means of groove gages (Fig. 2) and compared to the actual rope diameter. In this context, it is important that the pitch of the drum is 0.5 to 1.0 per cent greater than the actual rope diameter, as otherwise there would be permanent contact and friction between adjacent rope turns. Tis would cause wires to break and consequently reduce the rope’s life span.
l Check whether the rope entry at the point of attachment abuts the flange correctly. Check whether the rope entry at the point of attachment abuts the flange correctly. After all, warping at the rope entry and in the first layer affect the winding quality in all layers on the drum and thus also the rope’s life.
l Check deflection angles of the rope on the drum and between the sheaves. Te deflection angle on the drum varies from one position to the next, however, it must be ensured that the maximum deflection of angle a at the flange is between 0.5 and 1.5° (Fig. 3).
rope, which may damage the rope, as the rope will move up the flange of the sheave. When determining angle b, the angle of the
drum pitch a must also be taken into consideration (Fig. 4).
l Check condition of rope structure: Incessant winding and unwinding of the rope may cause the rope to be either twisted open or closed.
l As a result, the rope structure becomes either very tight or very loose. Using a screwdriver, one can easily check the condition and take corrective action as necessary. To do so, insert the tip between two outer strands and try to twist it. If it is easy to move the strands around, then the strand package is too loose, which in turn would shorten the rope’s service life.
About Teufelberger Teufelberger produces steel wire ropes for ropeways and cranes and is also active in the extrusion of plastic strapping products and baler twines. Te third pillar of the Teufelberger Group is its synthetic fiber branch. Te group is made up of the three following divisions catering to various market segments:
l Special steel wire ropes for applications such as cranes, ropeways, building and construction, industry, forestry, and slope winches, as well as personal fall protection equipment.
l High-tech fiber ropes for yachting, arboriculture, climbing, forestry and technical applications, and harnesses and ropes for personal fall protection equipment, metal-composite interconnections and overbraiding components
Fig. 4. Drum pitch angle a and rope deflection angle b.
A deflection angle that is too small will cause the rope to move up along the flange until it collapses and strongly affects the winding quality. If the angle a is too large, then this will result in a poor winding quality on a drum without grooves. On a grooved drum, an additional twist will be imparted to the
l Fibres and plastics for use in construction materials, wood and timber, baling, can and bottle, corrugted and printing industry; baler twines for harvest making fibre yachting ropes, high-performance industrial ropes, forestry ropes, and ropes for other technical applications, harnesses and ropes for personal fall protection equipment and arboriculture. l
Enter 34 or ✔ at
www.engineerlive.com/iog Günther H Gfrerrer is Head of Product Management & Technical Marketing, Wels, Austria.
www.Teufelberger.com 34
www.engineerlive.com
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