Moisture, salt, foliage, gravel, street dirt or rough construction debris, oil leaks: There is no limit to what these high-performance sweepers can tackle on large and small surfaces. They must be rugged and economical and also need to guarantee long service lives. Polymer plain bearings at particular trouble spots ensure long-term reliability. The experiences in the harsh everyday operation are so good that they are the first choice always for new areas of application.
"Our sweepers do not surrender before any demand," Dipl.-Ing. (BA) Helmut Schmeh, Managing Director of FAUN Viatec GmbH, a member of the German Kirchhoff Group, clarifies on site in Grimma. "They cover every work area and ensure a convincing sweeping performance even under the most difficult conditions. " Whether as a street sweeper for the daily work in municipalities or in the most severe use on construction sites, as an airfield sweeper to clean the runway tracks, or as a manoeuvrable sweeper for small areas: they prove their ruggedness worldwide. They show their efficiency even in the steel factories, coal mines, or in the removal of oil residue. Niches such as rail cleaning or weed removal are also covered with matching accessory implements.
"We attach utmost importance to the development of practical solutions that have proved themselves day in and day out in harsh everyday use," says Helmut Schmeh. "We are committed to the manufacturing base in Germany. Our sweepers are customised developments, unique pieces that are designed in close agreement with the respective requirements on site.
Although we make use of our modular system, the respective machine models are in the end result usually individually conceived so that they can fill a wide variety of problem areas. " Around 100 people are employed in Saxony.
The product range consists of a wide variety of truck-mounted sweepers. The chassis weigh between 7.5 t and max. 20 t on the scale. The structural volume is between 4 m3 and 9 m3. These are in all cases very powerful machines that need to justify all the cleaning requirements. "In many technical developments, we are trendsetters," says Helmut Schmeh. "Our patented air recirculation system, for example, provides maximum performance and operational reliability in conjunction with different standard chassis. We focus on current environmental issues such as drive technologies, fine dust reduction, fuel consumption and noise optimisation. At the same time, the vehicles are basically designed for low operating costs throughout the entire vehicle life.
The daily running time of the vehicles is usually high. Customers demand more efficient machines that need to be powerful and rugged in continuous use. No municipality and no service provider can afford long downtimes. But the fact is that the used components are also tremendously stressed by the enormous amount of dirt. "If metallic bearings are, for instance, not lubricated regularly, they wear out very quickly," says Dipl.-Ing. (FH) Gerhard Gräbel from the design department voicing a concern. "This not only limits daily working time, but it also has a cost. And lubricants furthermore pollute the environment." For these reasons, the company has been looking for a low-maintenance solution in the field of bearing systems already for a number of years, which requires no compromise in service life.
To ensure the long-term durability of the sweepers, the company decided to use lubricant-free and thereby maintenance-free polymer plain bearings from igus® GmbH, Cologne. Bearings from different iglidur® materials are used especially at critical points such as the disc broom, for example, which is exposed to high shock loads almost constantly when sweeping the kerbstones, and in the rear lid area which is exposed to strong forces while opening and closing. In addition extreme dirt accumulation occurs in both places, which affects all areas.
The particularly wear resistant iglidur® W300 on the one hand and iglidur® Q for maximum loads on the other are fitted in the lifting links of the disc broom. For this purpose iglidur® Z, the material with the maximum surface pressure at present, ensures a strong wear resistance in the hinge and latch of the rear lid. "The dirt is discharged via the rear lid. For it gets really too dirty and possibly also wet. Since we started to use the polymer bearings, there is no need of welding in case of repair," Gerhard Gräbel points out. "If at all a defect would occur in the vehicle today, only the plastic bushings need to be replaced. This is simple in comparison. And we have the bushings in stock in the spare parts depot.
The issues such as maintenance-free and lubrication-free, dirt-resistance, low wear, easy maintenance and high compressive strength have played the crucial role in the decision in favour of the respective polymer plain bearings. As they are already at the cutting edge of technology for years in the area of the rear lid and the sensitive pin/steel connections, which awkwardly called for regular lubrication, were successfully substituted the first day, a further development of the iglidur® Q material was considered for use in an area of the lifting links of the disc broom. It is iglidur® Q2.
The material is ideal for heavy-duty pivoting applications under extreme operating conditions. Wear-resistant and dimensionally stable at high loads, it ensures an even higher running time of the mounted sweepers. "Currently, we have a test vehicle running at a customer's site, whose results have not yet been finally evaluated," said the Managing Director. "If the calculations are correct, we switch to an even more wear-resistant material in a part of the disc broom.
The lifting links of the disc broom have been redesigned. Previously, the mechanical engineer relied on bronze or metal bearings with Teflon coating. "Our goal is to basically just put lubricant-free bearings on this extremely stressed point for all sweeper models in the future to guarantee our customers maintenance-free operation for years," the Managing Director clarifies the medium-term objective.
In the igus® test laboratory in Cologne, countless tests are conducted every year. The focus here are, for example, on material tests with high cycle rates, velocities, accelerations or demanding conditions. The components are provided partly by the customer. In addition to the normal surface pressures, the working processes of the disc broom, which pivot in and out continuously in the sweeping operation, are closely scrutinised in this application. Even the microvibrations of the vehicle has been simulated to represent the propelled sweeper.
"The test results demonstrate that the more brittle new material will probably withstand the daily stresses even better in the long term," the designer assures. "With it, the advantages for the machine operator are obvious. The rugged sweepers are economical in use over time with the simultaneous reduction of maintenance and service costs," adds the Managing Director.
The collaboration between the two companies worked very well. "We started our search a few years ago for wear-free materials at a fair and made the initial attempts with plastic bearings," Gerhard Gräbel recalls. "Our local contact is always available. We attach great importance to that. To preserve the value stability of the sweepers, we also need samples or spare parts at short notice. And in new or further developments, we now think in terms of plastic."
Even today more applications of the plastic plain bearings are planned. Metal bearings are, for example, still used in the area of the front broom. Also, they must be lubricated regularly to remain operational over time. The initial tests are already underway with lubricant-free plastic bearings.
Around 250 mounted sweepers are built at the site in a versatile series production every year. The specifications are clear. "Our customers demand efficient machines – with narrow economic specifications," concludes the director. "We score with class German workmanship. With our rugged and high quality sweepers of all sizes, a versatile range of cleaning tasks can be covered. In addition, we are sure that over time the lubricant-free bearings are set to be implemented in other places and will prove themselves and provide the required service life.