Vertical cable carriers: some design pointers
29 July 2011
There are a number of installation orientations that can be considered when working with a cable carrier system. In this article Justin Leonard examines the options available to OEMs and machine builders when working on vertical installations.
Flexible cable carriers are commonly horizontal, but they also offer a useful method of guiding and protecting cables in vertical motion applications. Two common configuration are ‘hanging’ or ‘standing’; a third, somewhat less conventional method, involves a ‘zig-zag’ arrangement. Each has its own design attributes.
Vertical standing configurations are often used in machine tool and pick-and-place applications, and generally involve shorter travel lengths. Factors to consider are how the cables are laid in the carrier and how they are secured at the end points. When installing cables, it is crucial that they can bend freely and have strain relief at both ends. Mounting brackets must also be attached so that the cable carrier does not bow outwards.
If lateral acceleration occurs, the carrier should also be supported along the outer radius. For taller standing applications, it is generally recommended that a minimum of the first three links on the outer radius be supported. For extreme heights and weights, the entire length of the carrier should be supported.
Vertical hanging carriers are often used with storage and retrieval systems, where gravity acts to maintain system stability. As with vertical standing systems, the way the cables are laid in the carrier and how they are secured at the end points, are important factors. When hanging the cables, it is crucial that they – and not the cable carrier - bear their own weight. The cables must be secured at both end points and interior separators used to prevent tangling.
A traditional carrier with camber is suitable for a hanging application if enough space is available. If not, a carrier without camber (pre-tension) will deliver optimum performance in limited space applications.
If the application involves vertical motion without lateral acceleration, the carrier can be installed without lateral support. If there is lateral acceleration, it should be guided laterally.
Partial guidance is also an option; however, at the very least it has to cover the area where the carrier might sway. As lateral acceleration can occur in two directions, lateral guidance must be installed accordingly. Also, keep in mind that additional guidance along the side of the carrier improves stability. Secure strain relief and clear separation of the cables are also key requirements, but remember that cables must be able to move freely and bear their own weight.
Where space is severely restricted, a less conventional configuration known as ‘zig-zag’ can be used. This type of installation is very common for lifts and stages within theatres and other event venues, where mixed cables (signal, power, etc) need to be housed and protected.
The author’s company offers carriers that can simply be reversed at any point to allow the system to fold over in a controlled way. This can be done several times to form a ‘zig-zag” style application, which is compact when stowed. And again, good cable separation, and strain relief is vital. It is recommended that a basket be provided to contain the carrier as it folds.
Justin Leonard is with igus UK, manufacturer of the Energy Chain cable carrier system. igus can provide advice on loads, stroke heights, bending radii and Energy Chain types. Wherever possible, more cost-effective approaches may be recommended, such as Energy Chains that combine both vertical and horizontal movements.
Contact Details and Archive...