GTA had been searching for a carrier unit to accommodate various attachments for a long time. It had to be sufficiently compact to remove material under constricted conditions when redeveloping tunnels. The machines available on the market were only suitable to a certain extent for working overhead in particular.
As a result, GTA got in touch with TML Technik, for their telescopic boom of the Unidachs 220 ripper, which TML originally devised for the metallurgical industry, can rotate by 360°. Thus, the machine possesses an additional level of freedom as opposed to articulated excavators: the attachments can be placed against the surface being tackled at practically any desired angle.
The machine, which GTA supplies under the name Multiripper 220, is suitable in mining and tunnelling, among other things for producing cross-passages, profiling tunnel cross-sections, scaling with a hydraulic hammer or a cutter as well as clearing, using different types of shovels. Furthermore, it can accommodate shotcrete nozzles as well as drill booms and tools for placing arches and anchors. The operator is able to work at a safe distance thanks to the remote-control system.
Owing to the compact dimensions and the high degree of manoeuvrability the MultiRipper is also capable of being deployed at points in tunnels, where other machines cannot operate: the width of the undercarriage amounts to only 1630 mm, its overall height is 2100 mm.
Maroggia Tunnel: Masonry removed with ongoing Train Services
The redevelopment of the Maroggia Tunnel on the Lake of Lugano provided an excellent opportunity to try out the capabilities of the MultiRipper under operational conditions on a tunnelling site. The SBB had decided to enlarge the tunnel cross-section within the scope of the Four-Metre Corridor Basle–Chiasso/Ranzo” project. The tunnel was only enlarged at one side on account of a special proposal, which shortened the construction time by roughly one and a half years.
During the project, the old masonry had to be removed and recesses created in the roof to install a crossbeam there. As a result, a great deal of work had to be tackled overhead, for which purpose articulated excavators are only suited to a certain extent. Some 200 trains travelling at roughly 80 km/h used the neighbouring track every day as work forged ahead. In this case too, the telescopic boom turned out to be the perfect choice since thanks to its design, no parts ever protruded into the other track’s clearance profile.
The Marti Company, the general contractor for the project, recognised the potential of the MultiRipper 220’s telescopic boom capable of rotating 360° and leased the machine for the duration of the construction period. For working in the tunnel, the machine was fitted with a hydraulic hammer weighing some 350 kg and set up on a platform carriage. In this way, the construction train could be driven out of the tunnel whenever space was needed to place concrete.
Compact Size, major Range
The MultiRipper 220 proved itself while operating in the Maroggia Tunnel. In spite of its compact size, the machine with its boom was able to reach the complete cross-section without having to be relocated, accomplishing the work in the roof with high precision.
Thanks to the remote-control system the operator was able to work at a safe distance and always had an optimal view of the working area.
Martin Frauenlob, Marti`s construction manager sums it up: “Thanks to the MultiRipper’s manoeuvrability, we were a great deal quicker than if we had used conventional articulated machines. Our employees were particularly pleased with the high precision, which could be attained especially when it came to producing the recesses for anchoring the crossbeam. And the remote-control system contributed enormously towards occupational safety”. As a result, Marti decided to purchase the MultiRipper 220 after construction had been completed so that it could be deployed for other projects.