Scharfenberg coupler

The Scharfenberg coupler[1] (German: Scharfenbergkupplung, abbreviated Schaku) is a commonly used type of fully automatic railway coupling.

Scharfenberg coupler on ICE 3 EMU
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Rail transport

Designed in 1903 by Karl Scharfenberg in Königsberg, Germany (today Kaliningrad, Russia), the coupler has gradually spread from transit trains to regular passenger service trains, although outside Europe its use is generally restricted to mass transit systems. The Schaku is superior in many ways to the AAR (Janney/knuckle) coupler because it also automates electrical and pneumatic connections and disconnections. However, there is no standard for the placement of these electro-pneumatic connections. Some rail operators have placed them on the sides while others have placed them above the mechanical portion of the coupler. The main disadvantage of the Scharfenberg coupler is the relatively low maximum tonnage it can support, which makes it unsuitable for freight operations.

Working principles

The face of the Scharfenberg coupler has a protruding cone and a matching cup. Inside the cone there is a rigid metal hoop connected to a revolving, spring-loaded metal disk with a notch on the opposite side. When ready to couple, the spring turns the disk so the hoop is extended from the cone. As the cars meet, the hoop enters the cup on the other coupler, stopping against the disk. The hoops are then pressed back into their own coupler, causing the disks to rotate until the notches align with the hoops. After the hoops have entered, the notches on the disks spring back into the hoop extended position, locking the coupling. In the coupled position, forces on the hoops and disk will balance out, which means that the Scharfenberg, unlike many other couplers, is not dependent on heavy latches to stay locked.

Small air cylinders, acting on the rotating heads of the coupler, ensure the engagement of the components, making it unnecessary to use force to get a good coupling. Joining portions of a passenger train can be done at very low speed (less than 3 km/h or 2 mph in the final approach), so that the passengers are not jolted. One problem with the coupler is that it is often hard to connect it in a curve. Planned coupling is normally done on a straight flat track, while there has been trouble coupling a broken down train at an unplanned place.

  • Layout of a Scharfenberg coupler (Labels in German)
  • Coupling process of a Scharfenberg coupler (Labels in German)
  • Uncoupling process of a Scharfenberg coupler (Labels in German)

Uses

Rail equipment manufacturers such as Bombardier offer the Schaku as an option on their mass transit passenger cars and locomotives. Presently, Scharfenberg couplers are in use on the following passenger transit systems:

United States

Canada

Europe

United Kingdom
This list is incomplete; you can help by adding missing items with reliable sources.


Brazil

Indonesia

Singapore

Thailand

Additionally, the coupler is in use on some multiple unit trains in Australia.

Types
Type 10 as used on TGV
The Shanghai Metro is among several metro systems that use the Type 35 Scharfenberg coupler

Voith is known to offer the following types of Scarfenberg couplers:[2]

  • Type 10: Used for mainline railways and high speed rail applications
  • Type 35: Designed for rolling stock without a compressed air system and used for urban transit applications
  • Type 330: Used for trams and light rail transit
  • Type 430: A folding coupler designed for low-floor trams and monorails
  • Type 55: Designed for shunting purposes
  • Type 140: Designed for industrial railways

See also

References
  1. us.voithturbo.com: Scharfenberg coupler
  2. "Scharfenberg couplers". Voith.
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