Back then, everything revolved around the drawing board. Rulers were attached to the drafting head at the end of a moveable scissor-type drafting machine – exactly like the one in the training room. Günther carefully places his hand on the drafting machine. ‘With this, you could create a precise design on A0 paper with exact angles,’ he says. At that time, the design engineers usually worked standing up. ‘The hallmarks of the design engineers were their ties, their white lab coats and the pens in their front pockets that often left ink stains,’ he recalls with a smile.

By the time he retired in 2001, Günther had witnessed the department’s transformation into the digital age. In the 1990s, the drawing board was gradually replaced by digital design tools. Today, computer-aided design (CAD) allows design engineers to create the most complex blueprints in 3D format, all within the confines of a computer screen – a far cry from the drawing board of the past.

Klaus Günther recalls that when they were designing on the drawing board, design engineers always had to have a clear view of the finished product in mind. ‘There was always a moment of truth when we would test the design in the workshop.’

In the early years, the company’s founder played a very hands-on role in coming up with new ideas. ‘Hans Liebherr used to enjoy dropping by the office and saying, “I have an idea.” Then we’d give him a pencil and paper and he’d start drawing,’ recalls Günther.

‘We had some lively debates with him. Many of his ideas were groundbreaking. Some led nowhere, and others were simply too far ahead of their time,’ says Günther. ‘The first hydraulic truck mixer, which we launched at the Hannover trade fair in 1968, was an idea that literally came all the way from the top.’

‘Tradition is very important,’ says Berthold Ruf, who started working as a development engineer for Liebherr Mischtechnik GmbH in 2002, one year after the departure of Klaus Günther. By that time, the drawing board had long been superseded by digital design programmes. The white lab coat and mandatory tie that once comprised the design engineer’s uniform were also long gone.

Ruf enjoys talking shop with a design engineer like Günther, who was around in the early days of the company. ‘Even with our latest fifth-generation truck mixers, we’re still dealing with many of the same issues as back then. It’s all about the technicalities of optimising load capacity and axle load distribution, while keeping everything as safe and efficient as possible,’ says Ruf.

‘Of course,’ he adds, ‘we have it a bit easier now than the design engineers did back in the early days. 3D design enables us to integrate more and more parameters, so we can simulate and model different kinds of load distributions and dimensions. This enables us to work more quickly, so we can focus more on the product and development process itself, without being too distracted by technical details.’

Electrical drive trains, telemetrics, driver assistance systems, networking and digitisation: ‘The world of truck mixers keeps moving ahead and we’re doing our part to keep the wheels turning,’ Ruf tells his predecessor. So, it’s just a question of more IT specialists then? ‘On the contrary, it still comes down to classic engineering skills. Like when we’re talking about designing steel components to weigh less but still offer the same load-bearing capacity and lifespan.’

And it’s always been that way, as Klaus Günther points out. ‘Every kilo of weight we can save on the truck is an extra kilo that the customer can transport on the road. For them, that’s money in the bank.’

Even though the times and job descriptions have changed, the goals of the design engineers are the same as always. To prove this point, Klaus Günther brought along a promotional postcard from the early days of the company, written to stir up interest among customers for the HTM6 truck mixer. It contained a message that came straight from the top: ‘Discover the HTM6’s many advantages for yourself – and make them all yours. All the best, Hans Liebherr.’