Flexible electrical control cable

In order to improve a multi-conductor control cable comprising conductor bundles utilized in container loading devices (spreader cables) so that it can transmit video signals, a stranded unit is provided in place of a conductor bundle. This stranded unit consists of only four stranded elements: an optical waveguide cable; a stranded element with a diameter equal to the diameter of the optical waveguide cable; and two additional stranded elements of smaller diameter.

BACKGROUND OF THE INVENTION 
The present invention relates to flexible electrical cables generally, and 
more particularly to the construction of a control cable that is utilized 
in container loading devices (spreader cables). 
A control cable is disclosed in EP-PS No. 0 178 249. This control cable 
contains several conductor bundles that are supported on a core element. 
In order to improve the physical conductability of such a cable when it 
experiences forces resulting from wind, the central supporting member of 
the cable comprises a binding of braided lead cords onto which a mesh of 
high-tensile strength plastic filaments has been applied. The conductor 
bundles each contain as a core element a braided lead cord. These braided 
lead cords are also arranged in the interstices between the conductor 
bundles. 
The control cable of the prior art cannot transmit signals of large 
bandwidth, particularly video signals. Thus, there is a need to modify 
such known control cables so that they can transmit signals of larger 
bandwidths, particularly video signals. 
SUMMARY OF THE INVENTION 
According to the present invention, this task is accomplished by providing 
a flexible electrical control cable comprising several conductor bundles 
supported on a central supporting member with braided lead cords arranged 
in the interstices between the conductor bundles. One of the conductor 
bundles is made up of four stranded elements, which include one optical 
waveguide cable, one stranded element with a diameter equal to that of the 
optical waveguide cable, and two stranded elements with smaller diameters. 
Consequently, an optical transmission element can be incorporated into the 
control cable without altering the fundamental structural design of the 
control cable. 
In the embodiment of the invention herein described the fiber optic cables 
are designed as hollow-core conductors containing several optical 
waveguide cables. These types of cables are disclosed in the German 
Published Patent Application No. 25 56 861 and DE AS No. 26 28 069. They 
consist essentially of a plastic tubing within which several optical 
waveguide cables are loosely arranged. A high tensile strength mesh 
encloses the plastic covering, which itself is enclosed by an outersheath. 
In the design of a control cable according to the invention, one conductor 
bundle contains two stranded elements that each have a diameter equal to 
half the diameter of the conductor bundle. Two additional stranded 
elements with smaller diameters are also contained within this conductor 
bundle. All the non-optical stranded elements are electrical control 
wires. The one control wire that has the same diameter as the optical 
waveguide cable has thicker insulation than the other control wires in 
order to achieve this larger diameter.

DETAILED DESCRIPTION 
Referring to the drawing, control cable 1 comprises a central supporting 
member 2 on which five conductor bundles are supported. Four of the 
conductor bundles 3, which do not contain an optical waveguide cable, are 
of the type known in the art and contain six control wires 7 that are 
twisted around a lead cord. The conductor bundle 4 includes one optical 
waveguide cable 6, one thickened electrical control wire 5 with a diameter 
equal to that of the optical waveguide cable 6, and two normal electrical 
control wires 7. Braided lead cords 8 and a filler 9 are arranged in the 
interstices between the conductor bundles. At the outside, the cable is 
surrounded by a braided core covering 10 with an outer sheath 11 
surrounding the braided core covering 10. 
The optical waveguide cable 6 includes a plastic tubing. Within the plastic 
tubing, three optical waveguide cables are loosely arranged. A high 
tensile strength braided covering and an outer sheath, enclose the plastic 
tubing. As noted previously, such waveguide cables are well known in the 
art.