Motion plastics, that is, low-friction maintenance-free plastic products, offer new solutions, especially for theatre and stage technology where there are very demanding technical requirements. These challenges include high loads, such as those found in sound and lighting systems, in stage sets or entire stage platforms, which must move safely and reliably. Physical and technical effects still need to be moved across the stage, but the systems themselves should remain unseen and silent so as not to interfere with the performance. The best solutions for stage technology are well hidden ones, with cables guided invisibly and silently. However, there is often only a small amount of space available to work in. Energy and data supply systems should therefore be silent, space-saving and also able to withstand high dynamic loads. They must be strong and hard wearing. The stage engineer needs systems that are easy to assemble, require little maintenance, and promise maximum service life.
Traditionally, cable reeling drums of various sizes are used for cable guidance on stages. But they are reaching their technical limits in many respects, especially in the capacity to accommodate different cable types, and they also generate noise. The igus e-spool provides an operationally reliable alternative that is ideally suited for complex and noise-sensitive applications. The system is very compact and can guide many different energy, data, control, or pneumatic cables together in very confined spaces. The design is a combination of two proven igus product families: long-lasting e-chains and the flexible "twisterband".
The continuous movement of the cables is reliable and safe due to the robust e-chain, which offers protection from external interference, wear, and tensile strain, and significantly increases the service life of the cables.As part of the readychain product range, harnessed energy chain systems, plug-in connectors and highly flexible cables are available from a single source – these are high quality, complete systems. The e-spool in turn protects the echain, which is safely stored on a drum. During the reeling, an integrated retaining spring maintains the correct tension on the chain at all times. The most important innovation is the use of the twisterband, which connects the spool to the shaft end block and forms the interface between fixed and moving cables. The twisterband allows continuous cable guidance during rotational movements without needing a slip ring, which is important because a slip ring has serious disadvantages due to the sliding contact. The abrasion created leads to wear, which in turn worsens the electrical power and signal transmission.
When it comes to the best signal and sound quality, such as in the upper machinery in Mountford Hall, one of the largest concert halls in Liverpool, the lack of slip rings pays off. There a customised cable guidance system with four e-spools supplying power and instructional signals for the entire loudspeaker system, so that the best possible sound balance is always achieved in halls of different sizes and during different events. The uninterrupted connection between amplifiers and speakers ensures the optimum sound. Even when using more e-spools in the upper machinery, the energy supply remains completely hidden from view. At the Culture and Congress Centre in Torun, Poland, 10 e-spools move the power cables for the lighting trusses. As the room configuration can be changed, the cables and connections have to be highly flexible and resilient – requirements that the e-spool system is designed precisely for. The Sydney Opera House also uses the e-spool for its upper machinery.
But the e-spool is also suitable for lower machinery, as seen in the Cologne Opera House. A total of 18 e-spools are located in the stage pit to deliver the necessary energy supply for stage floor operations. At the same time, all cables for control, lighting technology, audio and video cables as well as the electrical power supply must be cleanly routed. But here there is only a very limited vertical installation space available. Routed on the side of the podium legs to save space, they deliver totally concealed cable guidance, so that despite having 18 e-spools there is no visual obstruction and passageways remain free.
Depending on the application and filling, predicted service life is up to about one million strokes. After about 75,000 double strokes, the retraction spring must be replaced. Optionally, operators can equip the standard e-spool with one or two twisterbands. An e-spool with only one twisterband has a drum diameter of 600mm and can weigh from 13.5kg to 48kg. If you want to carry more cables, it is advisable to use an e-spool with two twisterbands. This version has a drum diameter of 850mm and weighs 40kg up to a maximum of 55kg. For heavy-duty applications, there is a special HD version of the e-spool standard. The retraction force can be increased, especially for heavy, vertical applications, for example in acoustic and lighting installations. Again, the e-spool HD offers a choice of one or two twisterbands.
The modular design and flexibility of the e-chains allow a creative solution for vertically hanging applications. If stages or heavy stage platforms must be moved, lifting heights of many metres and heavy cable loads must be managed. So far, systems that have been used are noisy, space-consuming and visually intrusive. With the "zig-zag" installation method using e-chains from igus, there is an effective alternative in a compact design. By using reverse bend radii, the e-chains can be stored in a zig-zag pattern, meaning very little space is required. When the stage or platform is raised, the e-chain unfolds with little noise. This installation method is possible with all echains of the E4 series. The entire e-chain practically disappears, as it is stored automatically in a standardised zig-zag box, which can be integrated in the stage pit or fixed on movable lighting trusses. As standard, travels of up to 40m can be implemented at speeds of up to 0.4 m/s and accelerations of up to 1 m/s2 . Even higher values are possible to custom engineer. The zig-zag principle has already proven itself in practice in a wide variety of applications. An example from theatre technology is again at Mountford Hall in Liverpool, where zig-zag e-chains are successfully used to supply lighting trusses with energy. At maximum height, the e-chains are fully retracted in their baskets directly above the crossbeam. If these are lowered, the e-chains unfold automatically. Every part of the design is space-saving and as unobtrusive as possible for the audience. An all-round flexible system that, as a specific customer solution, could only be created through close cooperation in design and execution.
Roger Kirby, installations director at Adlib Audio, the company responsible for it, praised the good collaboration: "We were able to work closely with the igus engineers at all times.”
The igus Liftband was designed for similar applications but following a different approach than the zig-zag method. It was developed for vertical applications up to 13m with lower cable loads, although higher fill weights are still possible with the use of nylon bands. Energy, data, and pneumatic cables can be moved together. E-chain speeds up to 1 m/s and acceleration up to 2 m/s² are possible. With a cable bend radius up to 250mm, the space requirement of the Liftband is exceptionally low. The Liftband is therefore the perfect alternative to zig-zag solutions, where very little space is available. The chain is stored in a solid steel basket, so that the retracted system is barely visible. However, for both the zig-zag box and the Liftband it is necessary to configure every application individually. Therefore, an igus designer should be consulted in the project planning.
In addition to theatre applications, "motion plastics” can be used in a variety of related applications for example cameras or moving screens. An example of this are the energy supply systems of the E6 series, which are in use in the studio of ARD-aktuell (ARD current news), where, among other things, the Tagesschau (daily news) and the Tagesthemen (daily prime time news) are produced. The former independent specialist for studio technology, Camerarobot Systems, was looking for a reliable guidance system for its three camera robots, that guaranteed both long service life at high loads and can work very quietly. The E6 modular system, which can be ideally adjusted to different travels, has chain links with a special design with abrasion-resistant connections, which ensure extremely low-noise and low-vibration operation. Additional noise-damping mats in the guide troughs ensure very high smoothness during tracking shots. Since the E6 can also be used laterally, it is well-matched for applications with tight design and space requirements.
Another compact and silent total energy and data supply system ideal for camera systems is the very small microflizz, proving even the smallest echains can master even long travels in a guide channel. Virtually no noise is emitted since a plastic spring attenuates the rolling noise of the chain in the channel. With an acceleration of up to 50 m/s2 , an operating speed of up to 6 m/s and data rates up to 10 Gbit/s, the micro flizz can execute fast tracking shots safely.