Maintenance-free polymer bearings for robust sweeping vehicles

"Our sweepers don't capitulate to any challenge," emphasises Dipl.-Ing. (BA) Helmut Schmeh, CEO of FAUN Viatec GmbH, a member of the German Kirchhoff Group, at the Grimma site. "They cover every work area and guarantee an impressive sweeping performance even under the most difficult conditions." Whether as a road sweeper for day-to-day work in local authorities or in heavy-duty use on construction sites, as an airfield sweeper for cleaning runways or as a manoeuvrable sweeper for smaller areas: they prove their robustness worldwide. They even demonstrate their efficiency in steelworks, coal mining and oil spill removal. Niches such as rail cleaning or weed removal are also covered with suitable attachments.

Extreme conditions such as moisture, salt, grit, coarse construction site dirt and oil spills make life difficult for the bearings used in the truck-mounted sweeper. Vibrations, shock loads and dynamics also have a strong influence on their service life. Bearings are needed that can withstand these operating conditions.

With plain bearings made of the materials iglidur ® Q, iglidur ® Z and iglidur ® W300, the individual application areas could be customised. Thanks to the freedom from maintenance and the improved downtime, the costs could be significantly reduced. The media resistance of the bearings makes it easy to clean the affected areas. Previously, certain bearing points had to be lubricated to prevent failure, replacement or welding of components. With the plastic plain bearings from igus®, wear only occurs in the bearing itself, which means that only the bearings need to be replaced.

The product range consists of a wide variety of truck-mounted sweepers. The chassis weigh between 7.5 tonnes and max. 20 tonnes on the scales. The body volume is between 4 m3 and 9 m3. In all cases, these are particularly powerful machines that have to fulfil all cleaning technology requirements. "We are trendsetters in many technical developments," reports Helmut Schmeh. "Our patented air circulation system, for example, ensures maximum performance and operational safety in conjunction with the various standard chassis. We address current environmental issues such as drive technologies, fine dust reduction, fuel consumption and noise optimisation. The vehicles are always designed for low operating costs throughout their entire service life."

The daily running time of the vehicles is generally high. Customers demand efficient machines that have to be powerful and robust in continuous use. No local authority or service provider can afford long downtimes. However, it is also a fact that the installed components are subject to enormous strain due to the enormous amount of dirt. "If metallic bearings, for example, are not lubricated regularly, they wear out extremely quickly," points out Dipl.-Ing. (FH) Gerhard Gräbel from the design department. "This not only ties up daily working time, but also incurs costs. And lubricant also pollutes the environment." For these reasons, the company began looking for a low-maintenance solution in the area of bearing technology a number of years ago that would not require any compromises in terms of service life.

To ensure the long-term durability of the truck-mounted sweepers, the company decided to use lubrication-free and therefore maintenance-free polymer plain bearings from igus®. Bearings made of various iglidur® materials are used, especially at the critical points such as the disc brush, which is exposed to high impact loads almost continuously when sweeping out the gutters, and in the area of the tailgate, which is exposed to high forces when opening and closing. In addition, there is the extreme accumulation of dirt at both points, which affects all areas.

The particularly wear-resistant iglidur**® W300** and iglidur ® Q for maximum load are installed in the lifting joints of the disc brooms. In addition, iglidur ® Z, the material with the currently highest surface pressure, ensures pronounced wear resistance in the hinge and the locking mechanism of the tailgate. "Dirt is unloaded via the tailgate. It gets really dirty and sometimes even damp. Since we started using the polymer bearings, we no longer have to weld when repairs are needed," Gerhard Gräbel points out. "If a vehicle develops a fault today, all you have to do is replace the plastic bushes. That's easy in comparison. And we have the bushes in stock in our spare parts warehouse."

"The test results make it clear that the more brittle new material is likely to withstand everyday stresses even better in the long term," says the design engineer confidently. "The advantages for the machine operator are therefore obvious. The robust sweepers are economical to use in the long term, while at the same time reducing maintenance and servicing costs," adds the CEO.

The collaboration between the two companies works very well. "We began our search for wear-free materials at a trade show a few years ago and subsequently conducted our first trials with plastic plain bearings," recalls Gerhard Gräbel. "Our contact person on site is always available. We attach great importance to this. We also need samples or spare parts at short notice in order to maintain the value stability of the sweepers. And when it comes to new or further developments, we are now thinking in terms of plastic."

Further applications of plastic plain bearings are already planned. For example, metal bearings are currently still being used in the area of the front brooms. They also need to be lubricated regularly in order to remain functional in the long term. The first trials with lubrication-free plastic bearings are already underway.

Around 250 truck-mounted sweepers are built at the site each year in a wide range of series production. The requirements are clear. "Our customers demand efficient machines - with tight economic specifications," concludes the CEO. "We score points with German workmanship. Our robust and high-quality sweepers of all sizes can cover a wide range of cleaning tasks. We are also certain that the lubrication-free slide bearings will prove their worth in other areas in the long term and ensure the required service life."