When it bought an LR 11000, Sarens came to Liebherr with the idea of investigating whether SPMTs (self-propelled modular transporters) could be used as ballast trailers. The benefit for the global heavy haulage contractor is obvious – it has KAMAG K24 SPMTs at almost all of its outlets.

The idea

The idea was not completely new, as Liebherr had already tried similar solutions with other
crane models. However, to date the SPMTs had never been controlled direct from the crane. Separate personnel had to communicate with the crane operator and enabled the SPMTs to track the crane’s movements.

Everybody involved in the project agreed that a solution now had to be developed to allow the SPMTs to be controlled by the crane’s control system, just like a standard ballast trailer.

The development

Sarens provided Liebherr with two K24 SPMTs from KAMAG for the development and testing work. And it soon became clear that it worked! Not only did the developers from KAMAG and Liebherr get on very well indeed, but so did the crane and the alternative ballast trailers.
Technical Director Carl Sarens and Project Engineer Hendrik Sanders saw the whole thing in action in October at the test site. And they were extremely impressed by the progress made in the project. Carl Sarens explains:

We are very satisfied with the results and the collaboration with Liebherr and KAMAG. All our requirements have been met and we are confident that this will deliver significant added value for future projects as a result of the operative benefits and flexibility.

KAMAG developed a special control box to ensure good communication between the crane and SPMT, enabling the crawler crane to control the movements of the heavy haulage vehicles. One helpful aspect of this was the fact that the Liebherr LICCON control system and the KAMAG control system have similar basic structures.

The solution

Jens Könneker from Liebherr Lattice Boom Cranes Product Management was able to
demonstrate a fully functional solution in November at an internal presentation – circling, moving in parallel, towing – everything works in exactly the same way as on a standard ballast trailer.

“Everybody involved here is delighted with the good collaboration with KAMAG and Sarens and the result is sensational”,

says Könneker.

To ensure that the tests could be started quickly at Liebherr, trials were conducted with a “standard ballast trailer without wheelsets” and a specially designed test adapter. Sarens’ LR 11000 is supplied to the customer as planned with a suspended ballast pallet. This is then placed on the SPMTs for jobs which require a “ballast trailer”, using a special adapter. If the “ballast trailer” is not required, the crane operates using suspended ballast. In this case the SPMTs can be used for other purposes – an economical solution.