Polymer bearings replace wearing brass bearings in slurry tankers

The new bearings work in the axle system of the tanker despite heavy soiling

The requirements for slurry spreading have increased enormously in recent years. Whether cattle, pig or biogas slurry: the aim is always to distribute the nutrient fertiliser evenly and economically on agricultural land without violating the fertiliser ordinance. This is where robust slurry tankers prove their worth. In the self-aligning axles from Zunhammer , lubrication-free polymer bearings defy all adverse operating and environmental conditions when discharging the aggressive slurry. Since they have been installed instead of the brass bearings previously used, there have been no more failures.

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Problem

The family business Zunhammer GmbH exclusively manufactures customised agricultural vehicles. Whether tyres, distribution or docking systems, pumps or working widths - as a rule, these are customised solutions made entirely in-house. This includes around 450 tankers manufactured by the family business over the course of the year.
When a slurry tanker is planned, all components are precisely harmonised. This applies to the tyres, the tank and the pump, but also to the chassis. Various axle systems and additional steering support options are available for the chassis. For some years now, a pendulum trapezoidal axle with hydraulic self-steering has been used as standard in the vehicles.
Brass bearings were previously used in the pendulum steering axles, but they were too worn. During transport and slurry spreading, the bearings were also exposed to heavy soiling and stresses. Lubricated bearings were therefore impractical. In addition, there is always a cloud of ammonia hovering around the vehicles, which also affects all components.
As agriculture is dependent on the weather, it is not possible to drive to the field in all weathers, so a slurry tanker is only in use on a maximum of 100 days a year. At this time, however, the technology must function 24 hours a day, seven days a week without any failures. There must be no technical faults whatsoever.

Solution

Four tribologically optimised iglidur ® Q polymer plain bearings with a diameter of 80 mm are now used in the pendulum trapezoidal axis. With plastic plain bearings made of the materials iglidur® G, Q and J, a suitable bearing was found for every position of the slurry tanker. Because they are maintenance and lubrication-free, iglidur® plain bearings are very insensitive to dirt and dust. In addition, the coefficient of friction could be improved, resulting in a longer service life.
While the wear of the brass bushings was too high, an effective and significantly more robust alternative was finally found with the polymer bearings. The bearings in the axis do not normally come into direct contact with the slurry. But it can splash violently during distribution, so that residual substances are deposited that cannot be removed immediately.
And while the rotation of the steering is low, there is still a particularly high surface pressure. The plastic bearings are perfectly suited here, as they are highly abrasion-resistant under extreme loads and insensitive to edge loads.
Tribo-optimised polymer plain bearings made of the material iglidur® Q have been proving their strength in the steering knuckle of the tandem axle since 1996. Since the lubrication-free bearings have been installed, there have been no more failures.

"The wear on the brass bushes was too high. Therefore, we were glad that the polymer bearings finally provided an effective alternative, because the plastic bearings are simply more robust."