Compact and robust in harsh environments: energy chain and cable in tunnel boring machine

• What was needed: energy chain system E4.1, E4/4 series energy supply systems with reverse bend radius (Reverse Bend Radius), chainflex® signalling and power cables
• Requirements: uninterrupted operation, harsh environmental conditions with high load levels
• Industry: Construction machinery
• Success for the customer: Pre-assembled chainflex® solution with energy chain and cable saves installation time, durable and stable energy supply solution ensures failure-free project execution

The tunnelling machines from Herrenknecht AG, Schwanau-Allmannsweier, are always tailored to the task at hand and its geological and hydrological conditions. In 2010, Herrenknecht was awarded the contract to build a tunnel boring machine (TBM) to construct a traffic tunnel in the Port of Miami, the "Port of Miami Tunnel". This is because almost 16,000 vehicles clog the roads to and from the cruise and freight harbour in Miami every day. Herrenknecht's solution is a TBM of the earth pressure shield type. The entire machine weighs 2,500 tonnes and is 110 metres long.

While all TBMs are custom-built, what they all have in common is that they are usually in operation almost continuously from the day they are commissioned until the breakthrough, which places high demands on load resistance, including with regard to the energy supply systems. These are needed because a whole range of different crane systems are used in the tunnelling machine for a wide variety of tasks. These are so-called material cranes, which transport pipes, cable drums and other workshop equipment from the supply vehicles to the respective work site, for example. These pipe-laying, cable drum and workshop cranes play an extremely important role in the overall process. They are responsible for the respective supplies. A workshop or belt material crane is used to extend the conveyor belt.

All the crane systems mentioned are equipped with two or three pre-assembled energy supply systems from igus® for longitudinal and transverse travel. One of these is the E4.1 energy chain system, which can be opened on both sides, is very robust and protects the inserted cables.
Robust energy supply systems prove their strength not only during material handling, but also in the erector, which is responsible for setting the segments. During segment lining, immediately after the drilling process, the tunnel is lined with segments in a ring under the protection of the shield casing. The segment segments are picked up mechanically or by vacuum using an erector, which is a remote-controlled manipulator, positioned on the tunnel wall and then bolted in place. The erector's action radius of +/-200° is realised with E4/4 series energy supply systems with reverse bend radius and 90° rotated installation position. 
E4/4 chains are characterised by high stability and torsional strength. They can be opened on both sides and can be fitted with various connection elements. Long unsupported applications - even lying on their side - are solved just as reliably as gliding applications. The e-chain® series has proven itself particularly in harsh environmental conditions.
Pre-assembly with bend-resistant chainflex® signalling and power cables from igus® has also been carried out.

Prefabricated complete system readychain® as a success factor

Not only the tunnelling machine itself, but also the components in the background had to be designed precisely to the respective requirements on site so that the tunnelling work could be completed within the specified time frame. As described here, this applied in particular to the E4.1 and E4/4 series energy supply systems, which proved their worth in the crane systems and, above all, in the erector directly behind the cutterhead, despite the heavy accumulation of dirt. "Durability and stability play an extremely important role," says Dietmar Stahl. "The energy chain from igus® impresses us with its material and design. We have been working together very successfully for several years." In the case of the mammoth Miami project, this also includes prefabrication with bend-resistant chainflex® signalling and power cables. Dominik Küntzler: "Among other things, this saves us a lot of assembly time. "Even if there is only limited installation space available, all cables are protected. The control cabinet can be installed separately. "This gives us the flexibility we need for this complex task."