Rediscovering the crawler crane that changed Liebherr
After 40 years of service, Liebherr's HS 870 has returned.
The homecoming of the HS 870
Manfred Brandl never thought that he would see the HS 870 again. Liebherr-Werk Nenzing, where Brandl worked for four decades, nearly developed completely differently and would likely still be building ship cranes today if it hadn't been for the HS 870 duty cycle crawler crane.
In 2014, the crane was discovered in a gravel pit close to Bonn carrying out lifting work day in and day out. The machine was rusty but steadfast even 40 years after it was built. The then sales manager for duty cycle and crawler cranes for Germany examined it himself and reported back to his colleagues in Nenzing: he had the prototype of the duty cycle crawler crane HS 870 with the serial number 181001. For Brandl, this reunion would become unforgettable.
What restorations did the prototype HS 870 need?
Jürgen Grass, Head of Assembly, has had to face many challenge in his 35 years of working in construction machine development. One thing was clear: more than just a fresh coat of paint would be needed to restore the HS 870.
A team of mechanics, fitters, engineers and apprentices got to work. Young, old, new and experienced employees helped. The undercarriage was in rough condition and required a lot of time and attention; the travel drive had to be restored completely. The steel covering had suffered during the many years of service and was built from scratch by apprentices. Valves were renewed, hydraulic hoses replaced and old pumps and motors were dismantled into their component parts, cleaned and reassembled. Besides original replacement parts, modern parts had also found their way into the HS 870.
Despite a long search, replacement parts couldn't be found for the headlight covers. The team had no choice but to replicate them with a 3D printer.
To Grass, the restored HS 870 is an example of what inventive talent and teamwork can accomplish. The team put more than 700 hours of work into the restoration, on top of their daily production.
"This is why it was so important to us to include our apprentices in the restoration," said Grass. "For them, everything was particularly exciting. They could experience how our HS series first started. Today our duty cycle crawler cranes are completely digital, in 1980 everything was still analogue."
New territory in the Alps
In the analogue years 1979 and 1980, neither Brandl nor his colleagues would have guessed that their work was to go down as a turning point in Liebherr history. It all began when the German construction machine manufacturer Menck went bankrupt.
At the same time, many different contractors approached Hans Liebherr Jr, asking whether his company could also build duty cycle crawler cranes. The company founder's son bought the bankrupt manufacturer's construction plans. After careful consideration, they decided to build a duty cycle crawler crane in Nenzing. Brandl became part of the group that built it.
Initially, the prototype wasn't popular with everyone: "We were a ship crane factory and had little to do with construction machines. The duty cycle crawler crane was a completely different product and did not really fit into the production portfolio. A few were grumbling behind closed doors," said Brandl.
In spite of the naysayers, it was to be a duty cycle crawler crane, and not just a Menck machine under a new name. The first Liebherr duty cycle crawler crane was to have a diesel-hydraulic drive and an electronic control system.
"At first, things were frantic," says Brandl. "After all, we didn't even know how a duty cycle crawler crane worked and to some extent, we had to define completely new manufacturing processes."
Equipped with the construction drawings of the Menck model M 750, the design engineers drafted a machine unknown to them, with novel hydraulics and a new drive system.
"We mechanical fitters in production received the construction plans pretty quickly and we got started. It was only during construction that we noticed that Menck's construction drawings were incomplete. There was a hitch in every corner," says Brandl.
What part of the HS 870 was the hardest to build and test?
When Brandl thinks back today, he remembers the assembly, the production of the covers and the tests on the test bench. And one particular component: the band brake. Without a band brake, there's no rope winch. No rope winch and definitely no working duty cycle crawler crane. Every time they thought they had found a solution for the brake, a new problem arose. Some versions saw the metal getting too hot when braking. With others, the metal broke or the rivets fell out. Nothing worked.
In April 1980, the whole group that had created Liebherr's first duty cycle crawler crane was invited to Bauma in Munich (Germany). The prototype was not only expected to meet high standards in terms of workmanship and functionality, but it also had to be visually appealing. The group from Nenzing stood around their machine, watched the hustle and bustle, held conversations and could hardly believe just how much praise they got.
"At Bauma, all the reputable construction machine manufacturers of the world present their products, but our HS 870 caught the eye of the expert exhibition visitors. It was a world sensation," says Brandl.
When Bauma ended, the prototype was directly handed over to its new owner Bilfinger Berger and was in active service on various construction sites for various owners all over Europe until it was rediscovered in Bonn, 40 years later.
The restored HS 870
The day he said his goodbyes after more than four decades with Liebherr, the retired Brandl was quite astonished when his staff presented him with his namesake Manfred #1.
"The restoration of the HS 870 was finished at the same time as my retirement after 42 Liebherr years. As a farewell present, so to speak, my first name now adorns this amazing machine. I'm very thankful for this and it makes me proud to be part of this Liebherr history," said Brandl.
The HS 870 is staying in Nenzing where guests and employees can visit and admire it. In the future, the first Liebherr duty cycle crawler crane will also be presented during customer days and events.
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