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Is it necessary to clamp the 'dead' end with 'live' end in the wedge socket?

Technical regulations "On the safety of machinery and equipment TR CU 010/2011 (paragraph 4 of the special safety requirements of lifting equipment Annex 2) contains such a requirement: "Quality mounting of ends and method of attachment of steel ropes is selected for provide the appropriate level safetyof mechanism and lifting machines in general".

Probably the basic criterion that provides this level of safety will be reliability of fastening wire rope. Moreover, firstly the wire rope should not fall out of attachment; secondly it should not be damaged during the operation.

Fastening of the rope end in wedge socket is used often enough: in the mobile, tower cranes, electric hoists etc... Wedge socket body is made of pressed, forged or cast steel. The use of welded sockets is not allowed. The size of the socket depends on the load capacity and diameter of used ropes. Fixing the end of the rope with the help of the wedge socket is the most reliable and self-sufficient way for holding on traction unit of lifting mechanism that does not require any additional ("safety") the method of fixing.

casar_sectional_view_wedge_socket.png

At the exit of the wedge socket the tail ‘dead’ rope end should be fixed with a wire rope clip. This will prevent the wedge from coming loose and possibly dropping out if the end connections are abruptly unloaded.

The wire rope clip must not be fitted in a way that connects the ‘live’ and the ‘dead’ wire line. Firstly, this will prompt considerably to reduce the breaking strength of the ‘live’ rope line due to the clamp forces of the clip. Secondly, the loaded rope line will try to change its length with every change of load. This, however, would be prevented by the unloaded, ‘dead’ rope line. A change of length would only be possible if the ‘dead’ line also changed its length, but it would have to take over some of the load in order to do so. This, however, would prompt to a tilting position of the socket every time the wire rope was loaded, and would, therefore, subject the rope to additional bending stresses at the exit of the socket.

dead_ending_rope_in_socket.png

Only the ‘dead’ end of the wire rope must be secured by a wire rope clip. Strangely enough, the thread length of a wire rope clip is not long enough to clamp a single rope line. Therefore, many installation fitters, already in doubt as whether to clamp one or two lines, are led to the wrong conclusion that they have to clip both the ‘live’ and the ‘dead’ line.

To correction the problem of too short a thread, several national regulations demand that the ‘dead’ rope line be clamped together with another short piece of wire rope.

A better solution, however, is to let the ‘dead’ end poke out further, and to bend it backwards into a loop. In this way the ‘dead’ line can be clipped together with its own end at the exit of the socket.

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