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Wire rope anchorages and fittings
Sockets
Working with wire rope? Find out about using sockets and wedge sockets as anchorages.
The eye on the anchorage for a non-moving rope (called a 'dead eye anchorage') must have a thimble. A splice with no thimble (called a 'bald eye splice') should not be used on an anchorage.
Wedge-type rope socket anchorages are used a lot for cranes where the hoist rope is re-reeved around the sheaves for extra purchase or mechanical advantage. These socket anchorages should comply with AS 2740 Wedge-type sockets.
Wedge sockets
The advantages of using wedge rope sockets as anchorages are:
- simplicity
- ease and speed of applying and detaching
- they do not damage the rope (to an extent that is noticeable or measurable).
Wedge socket
You must frequently inspect wedge sockets used on any wire rope. This is to make sure no slippage has occurred at installation and all pins are fully connected and secured.
How to use wedge sockets safely
Correct and incorrect wedge socket fitting
There are many dangers associated with wedge-type sockets. Riggers should make sure that they are set up correctly. Here's what to consider for the safe use of wedge-type sockets:
Rope diameter
The rope diameter should be equal to the diameter inside the socket. When the wedge is pulled tight, the wedge must not protrude beyond the socket body.
Hoist rope
The hoist rope should be reeved into the socket body so that there is a straight line between the live rope and the anchorage.
Rope reeving
Rope should not be reeved in the opposite direction. If the rope is reeved in the opposite direction so that the live end is on the sloping side of the wedge, the wire will fail where the rope enters the socket.
Rope grips
Do not place rope grips (bulldog clips) across both live rope and the dead end. Doing this can lead to severe damage to the hoist wire.
Note: Unless specified by crane manufacturers.
When to use wedge rope sockets
Wedge rope sockets may be used when:
- spliced eyes are difficult to reeve, or
- they would have to be made after the rope is in place.
Edges
Sharp edges must be rounded off at the point where the load bearing rope enters or leaves the socket.
Wedge angle
The angle of the wedge should be slightly greater than that of the socket. This is so that it does not nip the rope as it leaves the socket. The angle of the socket is important and should not be greater than 19 degrees.
Inspection
Socket bodies and wedges must be regularly inspected for too much wear at the point the wire rope strands are jammed into them. Do not use wedge rope socket anchorages where they cannot be easily inspected.
Dimensions
When a wedge rope socket with rope is assembled, the narrow end of the wedge should not protrude outside the end of the socket. Do not use wedge rope sockets where moving loads can force the wedge out.
Wire rope grip
A wire rope grip should be applied to the tail (only) of the rope below the socket. This is to prevent dislodgment of the wedge.
Use with earth-moving equipment
In earth-moving equipment (such as drag lines and pile drivers) the rope can be much longer than required at first. This is so that shortening can easily be done several times without recourse to splicing, unless stated by manufacturer's bulldog grip on the tail and live end.
Only use the bulldog on the tail of the rope as a visual indicator. Do not use on the live or load bearing side.
Sockets
Sockets are manufactured to Australian and other international standards for forged, cast of machined steel. Here's what to consider when using sockets:
Testing
To adhere to AS2759, the socket should be ultrasonically and magnetic particle inspected after manufacture. The wire rope and socket termination should be proof tested as per AS1666.1
Breaking load
Sockets should have more than the minimum breaking load of 1770 Grade steel core wire ropes. But other grades of higher tensile wire ropes are available and need to be matched to the end termination being used.
Second hand sockets
Second hand sockets must be MPI crack tested and approved for use. Refer to AS2759.
Poured sockets
AS2759 now states that all poured sockets should be proof loaded in accordance with AS1666.1
Poured socket
Closed swage sockets
Closed swage sockets have an efficiency rating of 100% based on catalogue strength of wire rope. They are ideal for use with 6X19 class and 6X37 class wire rope and galvanised bridge rope. Closed swage sockets are not recommended for use with fibre core and Lang's lay ropes.
Swaged socket
Other socket manufacturers
Some sockets may not meet the breaking strain of the wire rope. Seek advice in these cases and for very high grade (strength) wire ropes.