End assembly for wire strand

The invention provides an insert for use in retaining an end portion of a cable in a socket. The insert has first and second ends and defines a central opening extending between the ends. A portion of the opening adjacent the first end of the insert has a diameter which forms a loose fit on the center wire of the cable, and the remainder of the opening is at least as large as this diameter so that during assembly a filler material can be entered into space around the center wire in the opening. The invention also provides an end assembly on a cable using the insert.

This invention relates to an end assembly for cables of the type which are 
made up of a plurality of wires and more particularly to an insert for use 
in such an assembly. 
The word "cable" is used in this description and in the claims to describe 
a structure made up of a plurality of wires, one of the wires being a 
centre wire which is straight and the other wires being wrapped helically 
about the centre wire in layers. 
Cables are used in many structures as tensile elements. In every instance 
it is necessary to have an end fitting of some kind on the cable to anchor 
the end of the cable or otherwise attach it to a further element. Such 
assemblies must be capable of withstanding the maximum tensile load for 
which the cable is designed. Further, the method of preparing the assembly 
should be as fool-proof as possible and require a minimum of quality 
control. 
One method of preparing an end assembly involves the use of nails which are 
entered between individual wires from an end of the cable to separate the 
wires. Subsequently, this end portion of the cable is contained in a 
socket and the interstices are filled with zinc. While such an end 
structure is capable of transmitting the necessary tensile loads, it can 
not be inspected after assembly and it is possible for the assembly to be 
done using fewer than the required number of nails resulting in a weaker 
structure. 
The present invention provides an insert for engagement about a centre wire 
of a cable to provide an improved connection with a socket and also to 
minimize the need for quality control in such assemblies. 
Accordingly, in one of its aspects the invention provides an insert for use 
in retaining an end portion of a cable in a socket. The insert has first 
and second ends and defines a central opening extending between the ends. 
A portion of the opening adjacent the first end of the insert has a 
diameter which forms a loose fit on the centre wire of the cable and the 
remainder of the opening is at least as large as this diameter. 
Consequently during assembly a filler material will enter space around the 
centre wire in the opening. 
In another of its aspects the invention provides an end assembly on a cable 
using the aforementioned insert.

As will be seen in FIG. 1 a typical cable 10 has an end portion 12 inserted 
through a socket 14 and projecting above the socket to receive an insert 
16. The end portion 12 is separated from the main body of the cable by a 
serving 19 which is wrapped about the cable to prevent separation of the 
individual wires making up the cable. As seen at the top of FIG. 1, these 
wires consist of a centre wire 18 about which an inner layer of wires 20 
is wrapped helically and in turn this layer of wires is contained in an 
outer wrapping of wires 22. The centre wire 18 is straight and receives 
the insert 16 as will be described. 
After applying the serving 19 on the cable 10, the end portion 12 is 
slipped through a conical opening 24 in the socket 14 and angled sideways 
out of an eye 26 of the socket. The cable is placed in this position to 
provide access for engaging the insert 16 on the end wire 18. 
After positioning the cable as shown in FIG. 1, a pointed tool somewhat 
like an ice pick is used to spread the wires slightly to provide initial 
entry for a smaller first end 28 of the insert on to the centre wire 18. 
This wire is then engaged in a central opening 30 of the insert. It will 
be seen from FIG. 1 that the outer surface of the insert is conical and 
that a second end 32 is larger than the first end 28. Consequently the 
insert must be driven into the end portion until it takes up the position 
shown in ghost outline in FIG. 1. At this point it is contained within the 
end portion of the cable and the second end of the insert is about half an 
inch past the end of the cable. This placement of the insert causes the 
wires to fan out as seen in FIGS. 1 and 2. 
It will be seen from FIG. 1 that the opening 30 in the insert 16 is in two 
parts. This can also be seen in FIG. 2. A part of the opening 30 adjacent 
the first end 28 is cylindrical and proportioned for sliding over the 
centre wire 18 with enough space about the wire to receive filler 
material. However, the remainder of the opening 30 adjacent the second end 
32 is conical. The space so formed between the centre wire 18 and the wall 
of the opening receives filler material as will be explained to lock the 
centre wire to the insert. FIG. 2 illustrates the substantially uniform 
distribution of the wires 20,22 relative to one another and to the centre 
wire 18. This enhances the strength of the connection between the socket 
and the cable after the assembly has been completed. 
The next step in the assembly is shown in FIG. 3. Here the cable has been 
pulled away from the socket until that part of the end portion which 
contains the insert 16 is positioned within the conical opening 24 of the 
socket 14. It will be evident that because the cable contains the insert 
it will be impossible to pull the remainder of the cable out of the 
socket. However, it is not sufficient to simply rely on the positioning of 
the insert to retain the end of the cable in the socket. The final 
assembly must be capable of transmitting tensile forces between the cable 
and the socket. Consequently a filler material is used to hold the 
individual wires in position in the socket and to prevent separation 
caused by rotational or compressive forces. 
In this instance the filler material used is zinc. First the socket is 
preheated and molten zinc is then poured through the eye 26 of the socket 
into the conical opening 24 where it fills the interstices between the 
wires and the insert 16. The resulting assembly has a cross section such 
as that shown in FIG. 4 where the zinc can be seen between the wires and 
insert. However, it is also important to appreciate that in the preferred 
embodiment, the part of the opening 30 (FIG. 1) adjacent end 32 of the 
insert also contains zinc to lock the centre wire 18 to the insert. 
Consequently, tensile forces in the cable can be distributed among all of 
the wires including the centre wire because the wire is also a load 
bearing wire. 
It will be evident that some variation can be made within the scope of the 
invention. For instance, the filler material may be any suitable metal 
having a relatively low melting point or a suitable synthetic plastic 
material could be used. Also, the shape of the insert can be varied 
provided that it causes the necessary spreading or fanning of the wires. 
Two possible variations are shown in FIGS. 5 and 6. In FIG. 5 the outer 
surface of an insert 34 is stepped to provide similar results. 
In FIG. 5 the insert has a centre opening 36 which is cylindrical for 
engagement over a centre wire. In this embodiment because the opening 36 
is cylindrical there will be minimal load transfer from the centre wire to 
the end assembly. While this may be acceptable in some circumstances, 
normally it would be preferred to use an opening such as the opening 30 
shown in FIG. 1. 
The embodiment shown in FIG. 6 has a centre opening 40 which is similar to 
the opening 30 shown in FIG. 1 but differs in that the outer surface of 
the insert is tapered and ribbed longitudinally. The number of ribs 
corresponds to the number of wires 20 (FIG. 2) so that when the insert is 
engaged the ribs on the insert enhance the symmetrical positioning of the 
wires 20. Also, the insert provides a larger surface area than the insert 
16 (FIG. 1) which can be advantageous from the standpoint of bonding with 
the filler material. 
It will be evident that the socket 14 (FIG. 1) is typical of different 
fittings which can be used on the end of the cable 10 although such a 
socket is commonly used with cable. However, any fitting having an opening 
such as the opening 24 and which provides access for engaging the insert 
16 in the end portion of the cable can be attached according to the 
invention. 
The cable shown in FIGS. 1 and 2 comprises a central wire and two annular 
arrays or rows of helically wound wires. In larger diameter cables the 
size of the wires is not often increased but the number of rows of wires 
may be increased. Accordingly, where a cable having a greater tensile 
strength is required it may be desirable to utilize a cable having three 
or more annular arrays or rows of wires all helically wound about a 
central wire. In such a case it may be desirable to use an additional 
insert in addition to the first insert illustrated in FIGS. 1 and 2. 
Accordingly, where a cable comprises a central wire and at least three 
annular arrays of wires helically wrapped about the central wire the 
invention may advantageously embody a second insert. The second insert 
comprises a centrally extending opening which preferably has a diameter at 
least large enough to accommodate the first insert and at least two rows 
of helically wound wires. 
This embodiment of the invention will now be discussed in association with 
FIGS. 7 and 8 which illustrate a cable having three annular arrays of 
wires. 
As is best seen in FIG. 8 the cable comprises a central wire 118, a first 
annular array of wires 120, a second annular array of wires 122 and a 
third annular array of wires 123. Insert 116 accommodates the central wire 
118 in the manner described above with reference to FIGS. 1 and 2. Second 
annular insert 150 comprises a central opening 152. The central opening 
152 has a diameter sufficiently large to accommodate the widest section of 
insert 116 and in addition, the wires of helically arranged arrays 120 and 
122. 
The assembly is assembled similar to that described hereinabove with 
reference to FIGS. 1 and 2. The cable is passed through socket 114 as 
illustrated in FIG. 7 and the various wires are spread apart using the 
tool hereinabove referred to. Insert 116 may be then passed over central 
wire 118 as described above. Second insert 150 is then passed over the 
insert 116 and over each of the wires in the annular array 120 and 122 and 
inside the annular array of wires 123. The entire cable end is then moved 
into the socket and the filler material is then poured into the socket to 
fill all of the interstices between the wires and between the first and 
second inserts. The diameter of the central opening of the second insert 
is a matter of choice. The diameter may be chosen such that the second 
insert accommodates only the first insert and the first annular array. 
However, it is suggested that a more efficient system involves 
accommodating the first insert and the first two annular arrays. With this 
preferred system the third annular array would be accommodated on the 
outside surface of the second insert. Where cables are used having a much 
greater number of annular arrays of helically wound wires it may be 
conceivable that a third or further inserts can be used depending on the 
number of annular arrays comprising the cable.