{{Short description|Automatic railway coupling}} [[File:Voith_DAK_(2).jpg|thumb|Voith's DAK product 2024]] '''Digital automatic coupling''' ('''DAC''') is a type of [[railway coupling]] developed in the 2020s to replace [[buffers and chain coupler]]s, initially in Europe.
It resembles the [[Scharfenberg coupler]] with extra contacts to join electrical circuits (power, detection and control) and air hoses.<ref> [https://rail-research.europa.eu/news/digital-automatic-coupling-dac-the-backbone-for-full-digital-rail-freight-train-operations-in-europe/ DAC] DAC </ref>
The DAC project is backed by Europe's Rail, a body of the [[European Union]].<ref name="aa">{{cite web | url = https://rail-research.europa.eu/news/digital-automatic-coupling-dac-the-backbone-for-full-digital-rail-freight-train-operations-in-europe/ | language = en | title = Digital Automatic Coupling (DAC) – the backbone for full digital rail freight train operations in Europe | website = Europe's Rail | date = February 28, 2022 | access-date = April 11, 2023}}</ref> The system is among several innovations being developed within European working groups to harmonize the rail network and aims to boost freight traffic by 2030.<ref>{{cite web | url = https://www.sncf.com/fr/innovation-developpement/innovation-recherche/espace-ferroviaire-europeen/dac | title = L’attelage automatique digital de fret (DAC) | website = SNCF | lang=fr | date = March 30, 2023 | access-date = April 12, 2023}}</ref> Although not a member of the European Union, Switzerland is associated with the project and wants to subsidize the transition to digital automatic coupling on its territory.<ref name="Cormon 2">{{cite web | author = [[Pierre Cormon]] | url = https://entrepriseromande.ch/web/er/w/des-centaines-de-millions-pour-le-fret-ferroviaire-suisse | title = Des centaines de millions pour le fret ferroviaire suisse | publisher = Entreprise romande| lang=fr | date = April 25, 2024 | access-date = November 5, 2025}}</ref>
== Advantages == * Longer trains up to 750 m. * Brakes remotely controlled like [[electronically controlled pneumatic brakes]]. * Monitoring of train and wagon performance. * Safety. No need for [[shunter]] to climb between buffers.
== Function levels == {{anchor|DAC|DAC-3|DAC-4|DAC-5|DAK-3|DAK-4|DAK-5}} [[File:Voith_DAK_(3).jpg|thumb|DAK e-coupler (placed atop)]] Automatic couplers are categorized into five different levels in general. * no automation * Level 1: automated mechanic coupling (air pipes manual coupling) * Level 2: Level 1 plus automatic coupling of air pipes (partial uncoupling with a lever) * Level 3: Level 2 plus automatic coupling of power cables (allows uncoupling with switch) * Level 4: Level 3 plus automatic coupling of data cables (allows uncoupling at a signal) * Level 5: Level 4 plus remote automatic uncoupling
For the DAC the function levels are narrowed down to specific functions. The function level DAK-3 must connect the [[electronically controlled pneumatic brakes]]. The function level DAK-4 must connect the e-coupler including electric supply (400 V) and digital sockets. The function level DAK-5 must allow for [[#Uncoupling|remote uncoupling]] using an electric motor (the DAK does not use uncoupling air pipes as defined in EN 16019 for high-speed trains). Rollout plans may use function level DAK-4 when prepared for an update to DAK-5.<ref>{{cite web|url=https://blog.railcargo.com/en/artikel/dak-faq1|title=Part I: What is Digital Automatic Coupling and what are its levels?|date=2021-01-20|publisher=Rail Cargo Group|work=DAC Question & Answer}}</ref>
== Safe remote uncoupling == {{Anchor|Uncoupling}} In addition to uncoupling from the driver's cab, the DAC must also enable uncoupling while moving on the [[Classification_yard#hump|shunting hump]]. In addition to a mechanical device using a cable pull/uncoupling lever, the demonstrator also had an electrical device with switches on a control panel attached to the side of the car. Further development should enable electrical uncoupling both from the train and from a tablet or hump computer. This is essentially software development with high safety requirements.<ref>{{cite web|url=https://www.bav.admin.ch/dam/bav/de/dokumente/verkehrstraeger/eisenbahn/gueterverkehr/konzeptbericht-dak.pdf.download.pdf/Konzeptbericht%20DAK.pdf|title=Konzeptbericht - Automatisierung im Schienengüterverkehr der Schweiz, beginnend mit der Migration zur digitalen automatischen Kupplung|date=2022-10-24|author=Wolf-Dieter Deuschle|publisher=Bundesamt für Verkehr BAV (Schweiz)}}</ref>
== Other systems == Couplings based on [[AAR coupler|AAR]] and [[SA3 coupler|SA3]] already have automated mechanical couplings, so some of the advantageous features of DAC are lessened. These have a maximum draw gear load well in excess of that possible with the DAC, say 1800 m instead of 750 m.
== Makers == * [[Dellner]]<ref>[https://www.youtube.com/watch?v=AW-9wHoBab0 Dellner]</ref> * [[Knorr-Bremse|Knorr Bremse]]<ref>[https://www.railwaysafrica.com/news/automated-rail-freight-knorr-bremse-tests-digital-automatic-coupler-on-real-freight-train Knorr-Bremse]</ref>
== See also == * [[Railway coupling]] * [[Railway coupling by country]]
== References == {{reflist}}
== External links == * {{cite web | url=https://www.youtube.com/watch?v=TQ7HlmPljyA | title=Digital Automatic Coupling | website=[[YouTube]] | date=6 September 2021 }} * {{Cite AV media |url=https://www.youtube.com/watch?v=5y1ESfnkXac |title=DAC4EU - Operational Tests |date=2022-01-13 |last=DAC4EU Digital Automatic Coupling for Europe |access-date=2025-05-07 |via=YouTube}}
[[Category:Rail technologies]]
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