Diesel multiple unit

[citation needed] In a diesel–mechanical multiple unit (DMMU), the rotating energy of the engine is transmitted via a gearbox and driveshaft directly to the wheels of the train, like a car.

The transmissions can be shifted manually by the driver, as in the great majority of first-generation British Rail DMUs, but in most applications, gears are changed automatically.

In a diesel–hydraulic multiple unit (DHMU), a hydraulic torque converter, a type of fluid coupling, acts as the transmission medium for the motive power of the diesel engine to turn the wheels.

Some units feature a hybrid mix of hydraulic and mechanical transmissions, usually reverting to the latter at higher operating speeds as this decreases engine RPM and noise.

With diesel–electric transmission, some DMU can be no other than an EMU without pantograph or contact shoes (for use on the former British Rail Southern Region), which "is substituted" by one or more on-board diesel generators; this kind of DEMU can be potentially upgraded to electro-diesel multiple unit (EDMU), becoming a bi-mode multiple units train (BMU), just adding one or two pantographs or contact shoes (with opportune converters,[clarification needed] if necessary) and related modifications on the electric system.

The country's two largest towns, Zagreb and Split, are connected with an inter-city service that is provided by DMU tilting trains "RegioSwinger" (Croatian series 7123) since 2004.

While DB and regional transport authorities generally prefer electric power for commuter rail, many local and rural lines remain un-electrified, and DMUs are invaluable in providing services to those areas.

The national railway company CFR still uses, along with other DMU models, Class 77 and 78 DMUs, locally built by Malaxa between the 1930s and 50s and refurbished in the 70s.

The first significant use of DMUs in the United Kingdom was by the Great Western Railway, which introduced its small but successful series of diesel–mechanical GWR railcars in 1934.

At that time there was an urgent need to move away from expensive steam traction which led to many experimental designs using diesel propulsion and multiple units.

[5] These were few in number and relatively short-lived,[5] but they paved the way for the very successful InterCity 125 or High Speed Train (HST) units, which were built between 1975 and 1982 to take over most principal express services on non-electrified routes.

Commencing in the mid '80s, British Rail embarked upon its so called "Sprinterisation" programme, to replace most of the first generation DMUs and many locomotive-hauled trains with three new families of DMU: Following the impact of the privatisation of British Rail in the late 1990s, several other DMU families have been introduced:[citation needed] In 2018, the first bi and tri-mode electro-diesel multiple units were introduced: Canada generally follows similar buffer strength requirements to the US,[19] but new services are evaluated on a case-by-case basis.

As a result, several types of lightweight DMUs have been used: Costa Rica has purchased several Apolo 2400 series DMU railcars from the former narrow gauge operator in Spain, which are run in commuter service.

This has greatly restricted the development of DMUs within the U.S. as no other country requires the much heavier FRA compliant vehicles, and no export market for them exists.

[38] By January 2025, after 10 years of service, Bangladesh Railway announced its intention to sell the DEMU trains as scrap.

(キハ183系オホーツク・大雪) Speed: 110 km/h (max) Type: 特急　(Limited Express) Started: 1986 ............ End of Service in Japan 17 March 2023 DMUs (particularly DEMUs) are widely used in India.

These old trains had the loco controls duplicated in the Driving Trailer coach and all the actuation information reaching the locomotive through thin communication lines.

In Japan, where gasoline-driven railbuses (on small private lines) and railmotors (Kihani 5000 of the national railways) had been built since the 1920s, the first two streamlined DMUs came in service in 1937, class Kiha 43000 (キハ43000系).

[39] The service of several hundreds (in sum even thousands) of diesel railcars and DMUs started in 1950s following the improvement of fuel supply that was critical during World War II.

Initially built as gasoline-powered railmotors, the locally assembled Manila Railroad RMC class of 1929 was the first to be powered by diesel traction.

[49][50] From 2022 onwards, the PNR will purchase standard gauge DMUs for its upcoming inter-city rail network in Luzon and Mindanao.

On 14 January 2014, CRRC Changchun Railway Vehicles announced that hybrid electric multiple units were put into production.

0506 train, which uses an internal combustion engine and a battery hybrid, was used as a vehicle during the initial operation of the Xi'an-Huxian Railway.

The DHC (Diesel Hydraulic Car), which made its debut for the 1988 Seoul Olympics, was able to reach speeds up to 150 km/h (93 mph) and served Saemaul-ho trains.

The aim of this was connecting minor railway stations and stops on the main line where most express trains don't have a halt.