Rope binding

Thimble with ferrule

The rope binding , also called rope end connection, is a wire rope connection that enables wire ropes to be connected to structural parts or other fixed points reliably and largely in a way that is gentle on the rope. Since wire ropes, such as hemp ropes , must not be knotted, the rope binding is required as an aid for rope attachment.

Types of rope terminations

Various techniques are used in the design of rope bindings. There are different types of Seileinbänden, Kausch cover , cable lock, Molded cable sleeve and Pressed steel sleeve.

Thimble cover

A thimble , also called a thimble , is a ring-shaped or pear-shaped holding body, which is also known as a thimble heart. The thimble serves to reinforce the so-called rope eye. With the thimble a secure and reliable fastening for the wire rope is achieved. With thimbles with clamps, the crushing of the rope leads to a reduction in the rope's minimum breaking force.

Thimble with U-clamps

Thimble with U-clamp

With this type of thimble binding, the wire rope is placed around the thimble heart and then the end of the rope is attached to the opposite strand using U-clamps ( wire rope clamps ). The U-clamps are screwed on so that the clamps sit on the non-load-bearing part of the rope and the jaws on the load-bearing part of the rope. Although the connection by means of U-clamps is relatively simple, it is unsafe from a safety point of view, since high bending and compressive stresses occur at the point of contact between the wire rope and the clamp. Another disadvantage is that the wire rope can run through the U-clamps if the U-clamps have not been tightened enough or if the rope diameter decreases under high loads.

Thimble with splice connection

Steel cable splice connection, but without a thimble

This thimble binding uses a splice connection instead of U-clamps . The advantage of this thimble connection is the good power transmission. However, it is not suitable for wire ropes with different lay directions. The production of the splice connection is very complex. In addition, this thimble cover can only be created by specialists who have been specially trained in splicing technology.

Flemish eye thimble (spliced)

In the thimble with a Flemish eye , the end of the rope is first divided into halves with three strands each. Then the steel core is halved. The rope halves are then placed around the thimble eye and twisted into a complete bond. In addition, the strand ends are secured by conical steel ferrules with a conical shoulder. The advantage of this type of rope binding is that in the event of the clamp failure, a minimum breaking strength of 60% still remains. However, the Flemish Eye is only suitable as a rope binding for ropes with a steel core.

Thimble with ferrule

The end of the rope is connected to the opposite strand by means of a ferrule. The ferrule is usually made of an aluminum alloy. The ferrule is pressed onto the two pieces of rope using high pressure. The pressing creates a form fit and very good power transmission between ferrule and rope. However, special tools are required, and the application of the clamp is time-consuming with large cable cross-sections.

Rope lock

Wedge clamp with clevis

A rope lock or wedge terminal consists of a wedge-shaped housing and the wedge. The wedge is loose and is placed in the rope loop during assembly. Once the clamp is installed, the tensile force of the rope increases the holding force of the wedge even further. The end of the rope is secured to the rope using end clamps.

Pressed steel sleeve

Steel cable with pressed steel end sleeve and turnbuckle

For greater tensile forces or for aesthetic purposes, steel cables can be pressed into a steel sleeve. In contrast to the aluminum version with a thimble, this is done without a counter strand. Instead of the thimble, connections are available as fork heads, eyelets or threads.

Cast rope sleeve

Potting sleeve

With this rope connection, the end of the rope is encapsulated in the rope sleeve, also known as the rope pear. To ensure that the connection has sufficient tensile strength , the end of the rope is braided after insertion, and the rope sleeve is also conical in shape. So that there are no undesirable changes in the rope's safety-related properties, the connection is potted with materials that have a melting temperature below 500 °. The power transmission from the rope to the rope sleeve is very good after cooling. The casting of the cable end sleeves can only be carried out by specially trained specialists, and special tools and equipment are required. Rope sockets are available as fork rope sockets and as eyelet rope sockets. Round strand ropes and open spiral ropes are usually provided with press fittings as end anchors up to a diameter of approx. 40 mm, but larger rope diameters and fully closed spiral ropes are cast in steel sleeves using metallic alloys.

Individual evidence

^ ^A ^b Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary. 7th edition, Verlag Glückauf GmbH, Essen 1988, ISBN 3-7739-0501-7 .
↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Reinald Skiba : Taschenbuch Betriebliche Sicherheitstechnik. 3rd edition, Erich Schmidt Verlag, Regensburg and Münster, 1991, ISBN 3-503-02943-5 , pp. 361-363.
↑ ^a ^b ^c ^d ^e Richard Meebold: The wire ropes in practice. Springer-Verlag Berlin Heidelberg GmbH, Berlin 1938, pp. 39-47.
^ Carl Hellmut Fritzsche: Textbook of mining science. First volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1961, pp. 503–506.
↑ ^a ^b ^c Bernhard Kleinemeier: rope connections, rope end connections . In: Verein Deutscher Revisions-Ingenieure EV (ed.): Yearbook 1966. Bremen December 1966, 49–55.
↑ Roland Verreet: rope end connections. Engineering office for wire rope technology Wire Rope Technology Aachen GmbH (Ed.), Aachen 2012, pp. 31–42.
↑ Hans Bansen (ed.): The mining machines . Fourth volume, The shaft production. Published by Julius Springer, Berlin 1913, pp. 159–177.