Following selection of the received letters of reference provides insight into the value of the WONROS™ technology:

  • High frequency friction noise & wear reduction

  • Reduced vibrations declared by track side residents

  • Adequate traction/breaking results/safety

  • No soiling of ballast/rail vehicles

  • City friendly – no soiling of asphalt or danger for the traffic


The CL-E1® friction modification devices have improved the quality of life of the inhabitants of — as the squealing noise was almost completely eliminated.

Austria – March 27, 2017

In the post-lubrication state, the noise reduction was in the range from 2,6 dB to 15,8 dB for three different tram types. The highest reduction in noise levels was measured for the tram type – – – that emitted the highest noise levels at the pre-lubrication measurement. The pass-by noise levels typical of all three types became nearly the same.

Hungary – September 28, 2021

Our problem with noise has been solved completely. During the summer we do not have any problems whatsoever with sliding or gliding while passing the dosing fields. During winter, humidity and the ice on the rail causes modest slipping while accelerating or braking, but only in the vicinity of dosing fields.

Italy – January 10, 2010

In the study, by using the lubrication device CL-E1®, we achieved up to 14 dB noise reduction at low-frequency noise (630 Hz) and up to 30 dB noise reduction at high frequencies (3150 Hz).

Slovenia – October 4, 2012

Nine measurements on three different tramway types have been made to establish sound elimination properties of the DBM-KL® rail friction modification material. Squealing was reduced for 2,5 dB, 8,9 dB and 16,6 dB. The noise of the loudest tramway was reduced the most. All three tramways exhibited approximately the same noise after lubrication: 86,4 dB, 83,4 dB and 82,6 dB.

Poland – November 15, 2018

We have had problems with railway noise at the – – – train station where there is one of the tightest radii that is allowed in Germany for railway transport of passengers. We have tried other supplier’s solutions beforehand to resolve the noise problems, without success. In March 2021 we have installed ELPA CL-E1® device. With the use of DBM-KL® friction modification material it immediately proved its high efficiency. The device works without problems in the summer and winter conditions. We have proved reduction of rail wear in the curves. The breaking and traction were not negatively affected even when flange lubrication system on the trains was turned off. The inhabitants are very satisfied with the reduction of vibrations and noise. Regular maintenance enables reliable operation at low cost.

Germany – July 1, 2021


Measurements have been made to establish the efficiency of the CL-E1® system that distributes DBM-KL® friction management material on two curves. Results have shown that wear before (August 20, 2016 to May 12, 2017) and after (May 12, 2017 and February 6, 2018) the installation has been reduced by a factor of 3,17. On average wear was lowered from 1,14 mm to 0,36 mm annually per rail.

Poland – February 6, 2018

Between the years 2010 and 2013 several CL-E1® stationary devices have been built on the railway structure of Czech Railways. It has been established with measurements, that in a curve with a radius R=400 m the annual loss of rail was two times lower. Further, the stationary equipment CL-E1 fulfills following criteria:

  • the material is spread approximately 3 km from the dosing field, traces of material are visible all along the length
  • braking and traction effects are not changed

Czech Republic – June 4, 2013

On a 400 m long curve with six switches a very high wear of rails and switches was detected mainly because of “Hucke pack” wagon types with small and hard wheels. Even though using a graphite containing lubricant had been used, rails and switches needed to be replaced after 3-4 years. Because of good experience with CL-E1® devices applying CHFC composite material on other locations we have installed the device. In a very short time positive results were detected. There were no more metal fillings visible by the rails. Measurements after a year and half proved that wear almost completely stopped and as result maintenance in the curve costs are reduced for 50-100.000 € annually. Consumption of the CHFC material is cca. 8 kg/month.

Slovenia – December 27, 2010


Measurements were made by our company to establish effects of DBM-KL® friction modifying material on breaking performance of trams. Summary of the results is that at 30km/h and before applying friction modifier average breaking distance was 36,55 m. At the same speed and after the application of friction modifier to the rail, the breaking distance was shorter – 34,96 m.

Austria – November 19, 2015

Thin film of the friction modification material DBM-KL® was seen smoothly distributed till curve which is 1446 m from the location of the CL-E1® device. After that, traces were also seen on further curves. We did not find any material spillage on tracks. There was no slippage during rainy days, i.e., during the Southwest Monsoon period. We have noticed reduction of vibration and noise in the curves. The ride in these curves has been smoother after the installation of the device.

India – November 6, 2020

The CL-E1® device was installed on tramway rail type RI 60. On some places (—-) the railway is climbing steeply but there were no adhesion problems noticed so far. The consumption of the material is relatively low, we noticed significant noise reduction in curves as well.

Serbia – February 10, 2011


In June 2020 – – – GmbH introduced a new train – – – type – – -. Unfortunatelly the train was louder than the previous model and produced high frequency noise exceeding 105 dBA. Along the curve at —- it generated very strong vibrations that caused damages on the nearby buildings. After ELPA CL-E1® lubricating device was installed in March 2021 the noise was gone and vibrations were eliminated as well.

– – -, local resident, Germany – December 13, 2021


After longer observations, it has been proved, that the traction of the asphalt was not negatively influenced, by the small quantities of the lubricant that has been picked up from the rails by the cars.

Austria – September 28, 2020

In the years 2008 and 2009 we have installed different types of lubrication devices, mainly brands – – – and – – -. These devices did not function at low temperatures and during the rain the material was washed off the rails. In the area of devices, the rail roundabouts were soiled with excessive lubrication material. We had also big problems with the noise in the residential area. In April 2009 we have decided to install ELPA CL-E1® device and all the above-mentioned problems were solved. The device functions smoothly in the summer and in the winter. We are very satisfied with the device, and we recommend it.

Austria – June 7, 2010

The annual consumption of the friction modification material is very low – about 10 kg/(year*device). More than 95% of the material is used for the intended purpose, consequently, there is no lubricant pollution around the dosing fields on the tracks. Ties and ballast are kept clean.

Italy – January 10, 2010

The CL-E1® device uses the same material all year-round and the consumption of the material is not higher than 7 kg a month (on the main railway) devices operate normally also under extreme weather conditions and in the summer as well as in the winter.

Czech Republic – June 4, 2013


In the period from 2002 to 2015 for the purpose of installing CL-E1® lubrication and friction modification device, there have been 1470 holes Φ4 mm bored in the rails on dosing fields. We confirm that until now no problems whatsoever have been detected in the sense of malfunctioning of the devices or physical damages to the rails (chipping off, or breaking of the rail, or any other damages). The majority of devices are installed on the highest loadbearing routes.

Slovenia – December 21, 2015

Since 1991 our family has lived near the train station in – – – residential area and holiday resort. Residents and tourists have all been exposed to this unbearable noise up to 110 dB from 5 o’clock in the morning. Many videos exist as proof. Since the installation of the system right next to our house about two years ago, the system has worked flawlessly. Unfortunately, the system was out of order due to blown fuse, for several days, and the deafening noise was in town again. After the
fuse has been replaced, the trains are passing as if on soft soles again. It was only a lawsuit for € 300,000 for railway-caused depreciation of the value of my property that helped instal the ELPA device. It is strange that the management of the – – -, about a year before the assembly, was still of the opinion, there is no solution to rail squeaking. After more than 20 years, the problem was solved by a relatively small investment in about 6 hours. In addition, this system is self-financed, since according to the report, the wheels and rail wear are reduced by 50 percent. Again, many thanks in the name of us all who have suffered annoying squealing for more than twenty years.

The – – – family and residents of – – -, Austria – June 27, 2018

The trackside lubrication system »CL-E1® ug« has been put into operation in 2016 on our tramway network in a proper and professional manner. The deliveries and works were always carried out punctually and to our full satisfaction. The lubrication systems and the used lubricant contribute to improving the quality of life of our inhabitants, since the noise (squealing) is almost completely reduced! Furthermore, the low maintenance costs (rail lubricant filling only once per year) is a positive aspect. The used lubricant CHFC was tested with internal braking tests and was with full satisfaction confirmed by our management.

We would be glad to cooperate with the company again in the future.

Austria – March 27, 2017


From December 11, 2011 there have been installed 14 devices Bremex Annsys® Basic aimed at friction noise reduction on the marshalling yard in – – – . We confirm that the installed systems:

  • do not influence braking performance;
  • almost completely eliminate the high frequency brake noise at the source – its source being between retarders and wheels of the passing wagons;
  • the devices are functioning in all weather conditions, in summer as well as in winter;
  • parameters setting is enabled via lap-top computer;
  • the devices are applying environmentally friendly friction modifier DBM-50®;
  • yearly consumption of the friction modifier DBM-50® is within expected quantities;
  • the material has been used throughout the entire year;
  • the devices are operating autonomously and independently of the hump yard retarders.

Germany – June 4, 2013