Four Cat 330C HD Special Application Excavators on the World's Longest Tunnelling ProjectThe Sedrun intermediate adit is one of the most spectacular sections of the 2 x 57 km Gotthard base tunnel in Switzerland. It is executed by Transco, a consortium including Batigroup, Frutiger, Bilfinger Berger and Pizzarotti. Visit www.transco-sedrun.ch/seiten/transco-sedrun.htmThe actual tunnel construction site is developed using an access tunnel and two vertical 800 m-deep shafts, Sedrun I and Sedrun II. All men, machines and materials are transported via these shafts. Starting from the cavern at the bottom of the shaft, two 6.2 km-long tunnel tubes will be driven to the north and south. Avesco AG Langenthal, the Swiss Caterpillar dealer, has equipped this construction site with the key machines. To date, the fleet includes ten drilling vehicles, six loaders and numerous other machines. In order to ensure the highest reliability of the entire machine fleet, Avesco established a Sedrun construction site subsidiary, where 14 mechanics work at the moment. They provide maintenance and service support to all construction machinery 24 hours a day, 7 days a week. Visit www.avesco.chFor a few months now, a special excavator has been used at Sedrun. It was developed specifically for this construction site. The basic machine is a Cat 330C HD. In its series configuration, the machine weighs 37 tonnes. Its initial task is correcting the tunnel profile measuring between 8.5 and 13 m, using a hydraulic hammer or a ripper bucket. The height of the machine had to be minimised so that other tunnel construction machines and the excavator could cross each other without colliding. This task exceeded the capabilities of a conventional tunnel excavator. The dimensional requirements were fulfilled by manufacturing a shorter VA boom meeting the requirements for fastening all the special work tools.The hammer and the ripper bucket were mounted onto a hydraulic swing gear, similar to a grapple or demolition shears. The actual challenge for this design was the calculation of the power flow and the sizing of the different components. Rothe Erde, a company based in Dortmund, Germany manufactured the swing gear, designed to withstand the high loads and strong vibrations in this application. The load capacity of the double-ball bearing swing gear is relatively close to that of the excavator swing gear. This resulted in unmatched maneuverability of the work tool over the entire work area.Progress in the loose rock formation of the Tavetsch massif reached a maximum of one metre. Over this distance, three steel support profiles are installed. This represents another task for the Cat 330C HD special excavator. The work tool for installing the steel supports is a Profile Manipulator from GTA in Hamminkeln (Germany). This 1.3-tonne work tool can perform five different movements. As seen from the excavator's cab, they include 'Rotating by 360 degrees', 'Angling up to 90 degrees', 'Rotating the angled part by 240 degrees', 'Lateral movement of the grapple' and finally 'Open/close the grapple'. Due to the nature of the application, little space and presence of people, precision of the hydraulic controls and movement of the implements have high priority. As a tool carrier at high reach, stability of the machine is extremely important. This is being achieved by the high machine weight and the heavy duty dozer blade provides and additional stable platform. The controls for the manipulator are combined in a separate joystick. With the exception of open/close the grapple, all functions are controlled through proportional valves. This results in high precision and the corresponding safety. Visibility for the operator is improved by the hydraulic tilt function of the cab. Visit www.rotheerde.com and www.gta-maschinensysteme.deFor lowering the machine to the bottom of the shaft, a 30-tonne, 2.5 m-wide, 6 m-deep, 6.5 m-high elevator had to be used. In preparation for the move, the boom, counterweights and blade were removed. The upper and lower carriage were separated. However, they were still 3.2 m wide. To fit them into the elevator, they were installed into tiltable jigs. At the bottom, the machines were assembled and prepared for operation.Avesco is responsible for the project management, concept, execution and rights. However, the companies contributing to this project shall not remain anonymous. Fredi Stury AG in Rümlang, Switzerland was in charge of the design and manufacture of the swing gear and blade while Drago Engineering in Freienbach, Switzerland prepared the detailed geometric studies and the design of the boom system. Visit www.sturyag.ch and www.dragogmbh.ch The first machine, which was delivered in September 2003, has meanwhile proven its mettle. By end of May 2004, a total of four units will be delivered on site. Visit www.cat.com, www.alptransit.ch and www.basistunnel.ch. Click ch/17 & ch/22. 21/04.