Magnetic rail brake
A magnetic rail brake ( Mg for short ) is a brake for rail vehicles . It consists of iron grinding shoes with built-in electromagnets . When current flows through the electromagnet, the sanding shoe is pulled to the rail. Between the rail and the sanding shoe that is pressed onto it and moving forward with the vehicle, friction occurs which converts the kinetic energy of the movement into heat ( dissipation ) until the kinetic energy is used up or the brake is deactivated.
In addition, an eddy current induction occurs in the rail, which generates a force counteracting the movement. Since the frictional forces increase with falling speed and the eddy current forces decrease, the brake has a relatively linear effect over the entire area compared to a wheel brake with metal brake pads.
Use on main railways
In the case of main railways , the magnetic rail brakes are relatively far away from the rail when at rest; the German railway , for example, writes a distance of at least 5.5 cm in front. Otherwise, interference with track switching equipment can occur. In Germany, vehicles with a magnetic rail brake less than 40 mm from the top edge of the rail on one of the first two bogies may not be used as the leading vehicle if level crossings with a safety system of the EBÜT 80 design and wheel sensors of the magnetic rail contact Siemens, Siemens RSS (RSE 45 with ARS2 / ARS4) or Frauscher RSR122 should be used. Therefore, the brake shoes must be pneumatically lowered when activated; Only in the last few millimeters does the brake shoe magnetically pull itself onto the rail. Magnetic rail brakes must also function reliably in the event of a contact line failure. The braking system must therefore be designed in such a way that a supply from the vehicle's batteries is guaranteed at all times in the event of a power failure .
According to the Deutsche Bahn brake panels, journeys with a distant signal distance of 1000 meters with punctual train control (PZB)
- up to 140 km / h 146 braking hundredths
- up to 160 km / h 208 braking hundredths
required. More than around 170 brake hundredths are not permitted for vehicles in international traffic with wheel set brakes (e.g. block brakes , disc brakes or electromotive brakes ). If the load is even higher, there is a risk of the wheel slide protection system responding excessively .
The magnetic rail brake acts directly on the rail and is independent of the coefficient of static friction between wheel and rail. It is therefore used in Germany on all cars and multiple units that are PZB-guided and approved for speeds over 140 km / h. In wagons of locomotive-hauled trains and long-distance trains, the magnetic rail brake is switched off below a speed of 50 km / h due to the high braking forces and to protect routes that are usually only allowed to travel at 40 km / h. In Germany, the magnetic rail brake may not be used as a service or parking brake.
Only the ICE 3 , approved for 330 km / h , is the only high-speed series train of Deutsche Bahn to have eddy currents instead of magnetic rail brakes. In contrast to the magnetic rail brake, this brake system is wear-free, more efficient and can also be used as a service brake.
Use on trams
Since January 1, 1960, road-dependent trams in Germany have generally had to be equipped with a brake that is independent of the frictional connection between the wheel and the rail, which is usually achieved by magnetic rail brakes in order to achieve the prescribed braking deceleration of up to 2.73 m / s 2 in the event of emergency braking to deliver, so that the short braking distances necessary in road traffic are guaranteed even on slippery rails. According to the technical rules for BOStrab, a deceleration of at least 0.3 m / s 2 to 0.4 m / s 2 (depending on the speed) must be achieved with this brake . Tram vehicles not used to transport passengers are exempt from this rule, but may only travel at a reduced maximum speed.
In contrast to mainline railways, the magnetic rail brakes on trams are mounted very close to the rails (0.8 to 1.2 cm distance) and therefore usually do not need a pneumatic lowering device.
literature
- Supplementary regulation No. B 012 for the technical design of magnetic rail brakes in rail vehicles - Status: Rev. 5.4, May 22, 2012 . In: Supplementary regulations on the brake . No. 12 . Federal Railway Authority, May 22, 2012 ( eba.bund.de [PDF; 1.8 MB ]).
- Announcement 07 - AK EMC: requirements for the arrangement of the PZB vehicle magnets in bogies with magnetic brake (Issue 1.0 September 7, 2016) (= trade message . No. 24/2016 ). Federal Railway Authority, September 7, 2016 ( eba.bund.de [PDF; 193 kB ]).
- German Institute for Standardization V. (Hrsg.): Requirements for the function and performance of magnetic rail brake systems for rail vehicles; German version EN 16207: 2014 . Beuth Verlag , Berlin August 2014.
Individual evidence
- ↑ Martin Karr: Multi-system concepts for railways in Europe. Chapter 2.2 Clearance space and platform profiles . 1998, accessed February 17, 2017 .
- ↑ Martin Karr: Multi-system concepts for railways in Europe. Chapter 3.4 Karlsruhe - Project II , Section Safety System and EMC (Electro-Magnetic Compatibility) . 1998, accessed February 17, 2017 .
- ↑ Ril 810.0200A02 Section 6 Paragraph 2
- ↑ Ril 915.0101 Section 4 "Types of braking, braking with additional braking equipment" Section 10 (status 2006–2009)
- ↑ Ril 810.0200A02 Section 6 Paragraph 3
- ↑ Explanation on Ril 810.0200A02 Section 5 Paragraph 2
- ↑ BOStrab § 36 paragraph 6 point 1
- ↑ Udo Stahlberg: Technical rules for the dimensioning and testing of the brakes of vehicles according to the regulation on the construction and operation of trams (BOStrab) - Technical rules for brakes - (TR Br) . State committee for light rail vehicles and other track-bound local traffic systems (LSO), December 19, 2008, Appendix 2B, Table 3 Limits for the design of braking (rail brakes) that is independent of the traction wheel / rail , p. 36 .