Giants With Sensitivity

Before the series start from TraXon transmissions in mobile cranes from Liebherr, Liebherr and ZF engineers joined forces to develope features of the drive train.
Michael Scheibe , 26. March, 2018
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Michael Scheibe has been writing for the online magazine and our other publications in his capacity as editor in the ZF publishing team since 2016. He also functions as the link between external authors and ZF experts.
It is not only the location of the construction site that has it all, already is extremely challenging. Slopes of up to 20 percent and tight curves lead to a height of 1700 meters. Easy to handle for a passenger car, but a challenge for a mobile crane with a length of almost 22 meters and a weight of 108 tonnes. His name: Liebherr LTM 1750-9.1. This giant with a total of nine steerable axles has a maximum lifting capacity of 750 tonnes. The finely-tuned transmission system TraXon torque of ZF ensures that the performance of the 505 kW drive unit on the road. It is also the prerequisite for a precise maneuvering in tight construction sites.

The Liebherr-Werk Ehingen GmbH is the global market leader in mobile cranes. Since late of 2017, the Baden-Württemberg company equips its mobile cranes as standard with transmissions of TraXon series. "We deliver our cranes to over 100 countries worldwide, including countries that are extremely hot or extremely cold. Our cranes, and all their components, like the transmission, have to be able to cope with that,"", says Wolfgang Beringer. He is head of sales promotion at Liebherr.

Common special functions develop

Common special functions develop

In addition to the climate also construction in extreme situations place special demands on the transmission. To meet them reliably, Liebherr has an own test track on the Swabian Alb. There, engineers of the crane specialists and ZF, equipped all with TraXon-transmission system by ZF countless tests undergo. "Here we have a course with a challenging uphill and downhill profile that reflects the actual situations a mobile crane is used in," says Martin Dony, engineer in Crane Chassis Development and Construction at Liebherr.
"Intensive cooperation is the basis for equipping the world market leader's vehicles with the optimal driveline", ZF project manager and key account manager Oliver Salzbrunn adds. What this collaboration looks like can be illustrated by an example. Together, the experts of both companies develop additional functions for the TraXon gear specifically for mobile cranes. These include a comfortable driving program called ECOmode, a kickdown function, as well as a Hill Start assist.
ZF
Liebherr mobile cranes with TraXon in the endurance test

Long term business partnership

Long term business partnership

Liebherr and ZF are cooperating now for four decades. Then, in 1978, Liebherr with the LTM 1025 presented the first all-terrain mobile crane with a ZF PowerShift Transmission. A success story then wrote the AS-Tronic gearbox, that Liebherr used for 18 years in its mobile cranes. In total, ZF delivered from the location Friedrichshafen alone over 14,000 transmission to Ehingen. At the end of the year 2017, a new era has dawned. Since then, Liebherr equips its mobile cranes with three to five axes with a TraXon-transmission by ZF, vehicles with six or more axles get TraXon torque. The basic transmission with a converter clutch switch is combined with the TraXon torque. This allows a wear-free approach, as well as a gentle and comfortable maneuvering even at extremely high input torque and in the lower gears. "Our customers now get a vehicle with a very well-tuned transmission. In the test, we attach great importance to the fact that in all driving situations the tuning is optimal, so that the crane can drive perfectly on the road and in the area ", Martin Dony draws a more than satisfactory balance of the test phase.

With TraXon and a vast number of innovations in transmission hardware as well as control software, ZF sets new standards and ensures a tremendous functional diversity in the driveline. Examples are the new clutch release mechanism and shift control unit that are both more robust and so ensure the highest possible reliability. A new inclination sensor in the transmission allows the ideal gear selection in any extreme terrain.