{{Short description|Automatic railway coupling}} 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 couplers, 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}} 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 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 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 and 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<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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