Liebherr, a world leader in tower cranes, has developed a solution to handle the special hoisting tasks which are encountered in tunnel projects – the KFA crane conveying system.

Crane conveying systems are cranes which are required to carry out the horizontal transport of loads in one direction only, in a similar way to stationary gantry cranes.

Once the tests had been successfully concluded, the newly developed crane conveying system began proving just how good it was, and it has already demonstrated this in Malmö, Sweden and in Vancouver, Canada, a statement said.

These particular projects involved lifting the material excavated from tunnel boring in order for it to be carried away.

The Liebherr crane conveying system is made up in modular format from the standard crane components of tower, jib, hoisting winch and switchgear cabinet. This means that many standard components can be used from existing Liebherr equipment parks, and that makes a major contribution to cutting down the costs.

The towers and the frequency-controlled hoist gear and trolley travel gear are pure standard components, and only the jibs need to be slightly modified.

The programmable logic control and the safety devices are adapted for use with crane conveying systems too, and the modular format of the Liebherr components means that the system concept can be adapted to a wide range of different task situations.

There is a central control unit per load hook for the hoist gear and trolley travel gear. The control unit, with safety as a priority, and similar to the control system of a tower crane, is located in a climate-controlled switching station.

The electronic monitor system (EMS) displays all the relevant data of the load hook, which include the hook position, the hook load, and the speed.

The programmable logic control allows some defined operational sequences to be partly or even fully automated, which means economising on operating personnel. The automatic operation parameters are input via the EMS.

Additionally, the Liebherr crane conveying system also pro-vides the possibility of linking together both trolleys mechanically and both programmable logic controls in terms of control technology, which means that the working load can be doubled.

This type of hoisting is called for in particular, for example, when lowering prefabricated components into the general area of a tunnel. Parts can be lowered down to a depth of 370 metres, and excavated material can be conveyed out. – TradeArabia News Service