Cologne egg

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Technical drawing of the Cologne ice cream
Cologne egg when installed
Exhibition copy in the Cologne City Museum

The Cologne Egg is a rail fastening that reduces structure-borne noise, which is the cause of secondary airborne noise in buildings next to or above railway lines. The name "Kölner Ei" is derived from the characteristic oval shape of the rail fastening and from the city of the same name in which it was invented.

history

The Cologne egg was developed by Hans Braitsch at Clouth Gummiwerke in Cologne-Nippes and a patent was applied for on July 27, 1978 . The invention was based on an invention by his colleague Hermann Ortwein, which had already been registered on June 30, 1978. The Cologne Egg was first installed in 1978 on the Cologne light rail line Ebertplatz - Lohsestrasse . Due to the excellent results in the reduction of structure-borne noise , it was installed a short time later over a length of 1,500 meters in the track of the KVB (Kölner Verkehrsbetriebe) . Many other sections of the route followed.

construction

It consists of two metal parts, the ribbed plate and the frame, which are connected to one another by vulcanization based on NR ( natural rubber elastomer ). Due to its strength, durability, corrosion resistance and economy, ductile iron was chosen as the most suitable material for all metal components. Due to the good spring properties, the long service life and the optimal ratio of static to dynamic stiffness, an NR-based mixture is used.

The rail is attached to the rib plate. The frame is fastened with anchor bolts through certain applications that sit on the outside of the frame. The rib plate is supported by the vulcanized elastomer ring, which on the other hand is supported on the frame. This arrangement causes vertical forces to be divided into thrust-pressure components. This results in the excellent acoustic effectiveness of Cologne ice cream. In addition, the track width is reliably maintained due to the design. In the event of overloading, the ribbed plate lowers onto the concrete as far as it will go.

So that there is no hard impact here, the ribbed plate has a vulcanized elastomer profile on the underside. This maintains horizontal stability - a considerable gain in safety, especially in the arches. The elastomer ring that connects the frame and the ribbed plate not only dampens the vibrations, but also provides excellent electrical insulation. By adjusting the elastomer hardness, the vertical stiffness can be adapted to customer requirements.

The Cologne Egg usually comes with two mounts placed diagonally. Because the anchor bolts are on the outside of the frame, a non-positive connection can be established between the subsurface and the rail bearing. This means that the anchor bolts are only subjected to tension. This is not the case with many other camps.

commitment

The vibration-damping rail fastening is used worldwide, for example in Marseille , Washington , Boston , Sydney and London . In the inventor city of Cologne, around 14,000 copies of Cologne's ice cream are on the rail network.

In today's systems, the rails are stored in natural rubber from three sides. Such bearings were used in November 2013 when the north-south tram passed under Cologne Cathedral to dampen disruptive vibrations and shocks that were previously noticeable and measurable in the cathedral.

Web links

Individual evidence

  1. ↑ DE2832989A1 : Sound- absorbing rail bearings , July 27, 1978, applicant Clouth Gummiwerke, inventor Hans Braitsch
  2. ↑ DE2828714 : Device for the soundproof storage of heavy components , June 30, 1978, applicant Clouth Gummiwerke , inventor Hermann Ortwein
  3. ↑ Special dampers installed on the cathedral route in: Kölnische Rundschau , November 23, 2013, online , accessed on November 27, 2013