Jacobs bogies (named after Wilhelm Jakobs, 1858–1942, a German railway engineer) are a type of rail vehicle bogie commonly found on articulated railcars and tramway vehicles.
Instead of being underneath a piece of rolling stock, Jacobs bogies are placed between two carbody sections. The weight of each car is spread on one half of the Jacobs bogie.
Jacobs bogie Wikipedia
The first fast train using this type of bogie was the German Fliegender Hamburger in 1932. In the United States, such configurations have been used throughout the twentieth century with some success on early streamlined passenger trainsets, such as the Pioneer Zephyr in 1934, various Southern Pacific Daylight articulated cars, and Union Pacific Railroad's M-10000. Dallas Area Rapid Transit rail trains originally used a center bogie in a two unit car but have been modified to add a lower center section for handicapped level entry making a 3 unit car with two Jacobs bogies.
Vehicles featuring Jacobs bogies include the Alstom-made TGV and Eurostar trains, the Bombardier Talent series of multiple units, the LINT41, the Class 423 S-Bahn vehicles, the Canadian CN Turbo-Trains, several FLIRT trains, IC3 by Adtranz and the Škoda ForCity tram.
In Australia, Jacobs bogies were first used in 1984-5 on the B class Melbourne trams, used on two former suburban railways which had been converted to light rail operation.
Intermodal freight trains, such as Pacer Stacktrains, use container well cars in groups of three to five cars, connected as a unit with a connector assembly on top of a standard North American trucks between the individual well cars.
Some triple-bogied two-section electric locomotives such as the NZR EW class have an articulated body supported on the centre bogie. Other types of Bo-Bo-Bo locomotives instead use a body shell that has enough allowance for sideplay in the central bogie.
The Jacobs bogie can be found in trams (streetcars) such as the Tatra K2 and Oslo's SL79. The only 100% low floor tram with pivoting bogies, the Škoda ForCity, also uses modified Jacobs bogies.
On this crossover between the tram (streetcar) and the high-speed train, Jacobs bogies occurred on the latest equipment of any significance, the two Electroliner trains (1941–76). They were suited for streets with tight curves, the Chicago El and running through the countryside at approximately 140 km/h (87 mph). They served the Chicago–Milwaukee line and later the Philadelphia area.Safety, because the trains are less prone to collapse like an accordion after derailing. TGV have derailed one time at near 300 km/h, without death or severe injuries among the passengers
Lower weight and simpler and cheaper construction because bogies are heavy, expensive, and complex structures.
Less rail squeal and other wheel-to-rail noise because of fewer bogies.
The vehicles are semi-permanently coupled and can only be separated in the workshop. However, some flexibility may be achieved by coupling two or three trains together.
Fewer bogies and fewer wheels mean greater axle loads – if everything else is equal.
As cars are only supported at their ends, the middle of each carriage will describe a wider path on curves than independently-supported cars, thus requiring a wider loading gauge.