High Speed Grinding-Technology

Pioneer in preventive rail maintenance

Newly-developed HSG-city hybrid
Effective corrugation removal
Since 2013, the HSG-city has been used in numerous European and Asian cities and metropolises to remove corrugations and reduce noise emissions
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Numerous applications:
  • Mill-scale removal, head-check prevention and the removal of corrugations and greasy residues
  • Effective alternative to the grinding procedures used on specially monitored track
  • Switches with spring-action frogs without check rails can be machined as well
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Functionality & USPs
With High Speed Grinding (HSG), Vossloh is paving the way for preventive rail maintenance.
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Removes periodic indentations using corrective material removal
DB Projevt 4010
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Newly-developed HSG-city hybrid

Zero-emissions HSG-city

Effective corrugation removal

Corrugation-free longitudinal profile – guaranteed!

The transition can be made from partly corrective to fully preventive maintenance after only two or three grinding campaigns. The row of grinding wheels acts like a ruler.

Customer-oriented & transparent procedure: Condition-based rail maintenance – Noise reduction as an indicator of quality

Track audit and analysis
In future: Zero measurement before every grinding campaign
Grinding plan drafted specifically for the route
  • Consideration of known hot-spots
  • Fact-based integration of the infrastructure exposed to different rates of wear in the various track sections
Effective corrugation removal & prevention
  • Passively driven grinding wheels and sturdy series suspension in the HSG-city ensure that there are no periodic grinding patterns or tonality, as required by the specifications in EN ISO 3095:2013.
  • Measurements confirm qualitative improvements in the rail profile over the years

Removing corrugations: Undercutting achieves “corrugation-free” rails

In order to reliably counteract the damage, alternating areas of hardness in the rail surface must be prevented in order to stop corrugations from returning or reversing.

“The rediscovered passenger comfort is amazing! There’s a lot more grip and a lot less squealing in the curves.”

Except from an e-mail sent in by a tram passenger in Le Havre

„With the HSG-city, we‘ve found an adequate tool for noise-mitigating rail maintenance. Not only is this confirmed by the regular corrugation measurements, the significant reduction in the number of complaints from residents is unequivocal proof that the cyclical grinding campaigns are effective. What’s more, the compact grinding machine gives us the freedom to fully machine the expansive network twice a year and also carry out special deployments such as removing greasy residues.“

Peter Ahrens, Head of Track Systems at Rheinbahn AG in Düsseldorf
After the HSG-city campaign in Le Havre

Functionality & USPs

How the HSG grinding process works

  • The unique feature of this method specially for preventive grinding is the high grinding speed of up to 80 km/h, which makes it possible to grind in train mode inside the regular train timetable.
  • HSG not only removes rail defects like head checks and corrugations, it also reliably prevents new defects from forming and thus extends the service life of rails by up to 100 %.
  • Their angled orientation to the rail causes the peripheral grinding wheels to turn by themselves (passively driven)
  • Due to the elelongated area of contact, the grinding wheels remove brittle surfaces (hardened surface layer) and the beginnings of corrugations and slip waves.
  • The grinding intensity and output are determined by the speed of the traction vehicle and the grinding pressure.
  • The aim is to remove 0.1 mm in three to ten passes.
  • The existing rail profile is not altered because the grinding wheels take on the profile of the rails and not the other way around.

Effective removal of corrugations

Comparison of grinding methods

Now in more than 10 countries (> 300,000 km of grinding work done)

  • On almost all of DB’s main lines and on all the German high-speed lines
  • Used on all PDLs in China for prevention, reprofiling and removing mill scale from newly-laid rails
  • Officially recommended by the Chinese ministry for the maintenance of PDLs since 2019
  • Since 2013, HSG-city has been used in numerous European and Asian cities and  metropolises for removing corrugations and reducing noise.

Numerous applications

Application examples of HSG-city

Corrective removal of periodic indentations

Initial situation on the Deutsche Bahn line 4010 Mannheim – Frankfurt:

  • Periodic indentations in the gauge corner zone
  • Maximum removal depth of 0.4 mm
  • As it was not possible to close the line, the rails had be machined at night

Solution: HSG-2

  • Using 18 passes over 6 nights (20 passes in some places)
  • Selective monitoring at a total of 5 test points on the tracks in both directions

Result:

  • The amount of metal agreed on for removal was achieved.
  • Indentations completely removed
  • Rail roughness determined to be medium quality class 1
  • The rail‘s existing transverse profile was retained to a very large extent.

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