A Jakobs bogie ( JDG , also Jakob frame ) is a type of railway - bogies , two consecutive in the vehicle car bodies are supported on a common bogie. The bogie is located directly under the transition between two wagons (parts) that are permanently coupled to it. It is named after its developer, the railway engineer Wilhelm Jakobs , who applied for his patent on August 8, 1901.
The individual wagons in trains with Jakobs bogies are always shorter than comparable wagons of the classic design, as they have no external overhang. The weight advantage that can be achieved by saving one bogie per car transition is therefore lower. However, since the bogies are relatively heavy components, the savings should not be neglected; In addition, the relatively heavy couplings between the cars are saved. One disadvantage of Jakobs bogies is that the vehicles can only be separated in workshops, while they form a non-separable unit during operation. To do this, one side of the separation point must be jacked up and an auxiliary bogie inserted. The saving of one bogie per wagon leads to a reduction in the number of wheels, which in turn limits the constructively possible wagon weight compared to standard wagon types.
Was the first successful use of Jakobs bogies in fast rail transport in Germany in 1932 the Flying Hamburger and in 1935 it entered service speed rail cars of the Hamburg Design and the 1938-built Multiple Unit 137155 construction Kruckenberg . In 1934, this design feature was used in the first American streamlined trains M-10000 and M-10001 of the Union Pacific Railroad and the Pioneer Zephyr on the Burlington Route .
Current vehicles with Jakobs bogies are, for example, TGV , AGV , Talent , Lint 41 , Flirt , the German ET series 422 , 423 , 424 , 425/426 and Alstom Coradia Continental as well as the type IC3 from DSB , which is also used in Sweden and Israel is used.
Compared to the previous 420 series, the 423 series is a good example of the advantages and disadvantages of Jakobs bogies. While a class 420 multiple unit consists of three cars with two bogies each, the class 423 has four shorter cars with a total of five bogies. With the same overall length, a bogie is saved and an additional car body is required to maintain the wheel load. Both trains are the same length except for a few centimeters.
In trams can be found Jakobs bogies - having close cars journals - often because they for the construction of articulated railcars are suitable. The wagon ends of conventionally coupled wagons move heavily sideways as soon as a wagon is in a tight curve and the attached wagon is on a straight line. Due to this pronounced offset, a walkable transition for passengers can only be implemented with great effort.
Due to the design, the pivot spacing of the individual wagons is larger and the passenger area is located completely between the bogies of the wagons, similar to a sedan chair , although the wagon bodies are actually shorter. As a result, horizontal or vertical movements of the car bodies are better balanced than with classic car trains. This leads to an overall quieter driving behavior of the train and is particularly important at high speeds.
As an illustration:
- On the ICE 3 , the length of the car is 24.775 m, but the distance between two bogies of a car is only 17.375 m. The distance between the bogies between two cars is 7.40 m. In the train formation, bogie distances of 17.375 m and 7.40 m alternate continuously.
- With the TGV, on the other hand, the length of the car is only 18.50 m, but the distance between the bogies is 18.70 m evenly distributed over the entire train.
Jakobs bogie on the intermediate car VT 10 551 , a diesel multiple unit from 1953
TGV Jakobs bogie, here at a Euromed unit in Valencia Norte
Alfa Pendular bogie
Articulated trains such as the VT 10 501 "Senator" of the German Federal Railroad (until it was closed in 1960), the first Spanish Talgo trains and the UAC TurboTrain in the USA manage with one axle between or on a car body. In 1942, Talgo used triangular chassis that deflected the wheels of the chassis in front.