Electronically controlled pneumatic brakes

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Electronically controlled pneumatic brakes are a type of modern railway braking system which offer improved performance compared to traditional pneumatic (compressed air) brakes.

Overview[edit]

Traditional systems apply the brakes sequentially from car to car along the train, meaning that up to two minutes can elapse between operation of the control valve on the leading locomotive and the application of brakes on the last car of a 150-wagon freight train.[1] In contrast, ECP braking uses electronic controls which make it possible to activate air-powered brakes on all the wagons throughout the train at the same time. Applying the brakes uniformly and instantaneously in this way gives better train control, shortens the stopping distances, and leads to a lower risk of derailment or of coupling breakage.

The ECPB can also apply the brakes on the rearmost wagons, slightly before the brakes on the front wagons are applied, which reduces the shock and noise of the wagons bunching up.

Testing[edit]

During initial testing the ECP equipment had software glitches, and problems from the ingress of moisture into the equipment. These have now been resolved.

Greater intervals between brake tests are also likely because of the ability of ECP brakes to self-diagnose which should generate large cost savings that will help pay for the system to be installed.[2]

The benefits are better control of braking, less equipment wear from pushing and pulling between cars, shorter stopping distance and improved headways.[3]

Control and power[edit]

When first developed, ECP brakes needed a number of wires along the train to control solenoids on each wagon to release the brakes, and were not considered economic for freight. This has changed with the introduction of electronic controls, allowing data to be transmitted by two-conductor wire or radio from the locomotive to a microprocessor on each car, where locally powered valves hold the desired pressure in each brake cylinder.[1]

Use on Fortescue Railway[edit]

ECP can use axle-generated power or wire-distributed power. The Fortescue railway uses wire-distributed power at 200 V DC. The Fortescue line also places the two brake pipes and single control/power cables on one side of the wagons only, as trains operate only as block loads and the wagons are not normally reversed.[4] Having the wires on one side avoids the need for crew to stoop under the coupling, as would be the case with the normal configuration where the hose and wire cross under the coupling.

Compatibility[edit]

ECP brakes by the two manufacturers are meant to be mutually compatible.

In the case of the Fortescue railway, the new ECP brakes are incompatible in several ways.

  • The wagon-to-wagon pipes are straight and are on one side of the wagon only, and do not cross over to the other side underneath the coupling.
  • Wagons are one-sided, though locomotives are dual-sided for flexibility. The wagons are one-sided to suit a rotary tippler.[5]

Progress and examples[edit]

  • United States 1990s- first trials on BN in the 1990s TSM of Kansas City operated more than eight coal and intermodal trains using their "EABS" ECP for BN, CP and Amtrak. TSM was purchased by Wabco in 1998.
  • United States The first ECP-equipped Norfolk Southern train in the United States began operating on October 11, 2007 with the Norfolk Southern Railway.[6][7]
  • South Africa Testing of ECP braking on Spoornet's Richards Bay heavy haul line in South Africa was also expected to begin by the end of 2007, for service in 2009.[8][9]
  • United States January 24, 2008:- first trials on BNSF [10] BNSF retrofit 300 Powder River Basin coal cars with Wabtec ECP-4200.[11]
  • Australia ECP braking is also being tested in Australia.[12]
  • Australia May 2008: new Fortescue iron ore railway has ECP.[4]
  • Canada September 2008: Canadian Pacific Railway has begun testing ECP-equipped coal trains on its coal haul route in British Columbia.
  • United States November 2008: According to RGI [13] the two systems from NYAB and Wabtec are meant to be interoperable, but testing to confirm this has yet to be carried out. Federal rules limit normal air brake inspection to once every 1600 kilometers, but with ECP this increases to 5600 kilometres, allowing a coast-to-coast return trip on a single inspection at home base.

Distributed power[edit]

Main article: Distributed power

Distributed power is a system where locomotives are coupled in the middle and/or end of a heavy train and remotely controlled originally via radio from the locomotive in the front. Amongst other advantages, this reduces coupling stresses in long and heavy trains. The ECP wiring can also be used to control these intermediate locomotives.

Parameters[edit]

  • Standard = Association of American Railroads S-4200
  • Train Length = 3,658 m (12,001 ft) maximum
  • Wagons (Network Devices) = 180
  • Wired Distributed Power (WDP) = 230 V DC

See also[edit]

References[edit]

External links[edit]