Technical parameters of railway vehicles: Legendary Y25 bogie

Technical parameters of railway vehicles: Legendary Y25 bogie
photo: bogie
06 / 01 / 2021

The two-axle Y25 bogie was adopted by the International Union of Railways at the turn of the 1960s and 1970s. It was adopted as a standard bogie to be used for freight wagons. This happened after long-term research. The parameters of this chassis were determined by UIC 510-1. In addition to the standard Y25 chassis, the Y25Cs variant was also introduced.

In our territory, then within the Československé dráhy’s fleet, these chassis appeared thanks to cars that were purchased abroad. An example is the Kas cars, which were delivered between 1974 and 1978 from Hungary. Another example can be wagons from Romania, Na 67 group, which were imported from 1977 to 1983. However, they had the already mentioned variant of the Y25 chassis, i.e. the Y25Cs chassis.

Production of the Y25 chassis did not start in Czechoslovakia until the 1980s, at the workshop in Česká Lípa and in Poprad. At first, it was only the assembly of already imported components. However, a production line was soon built in Vagonka Poprad, which enabled the complete production of these chassis. Thanks to this, it was possible to produce chassis, which were installed, for example, on cars Uae 51, 52 and 53 group.

The Y25Cs and Y25Rs are among the most used Y25 chassis in the Czech Republic. The biggest difference with the Rs chassis is that it has preparation for fitting a load cell from the DAKO manufacturer. Larger diameter springs are also mounted on it. We will not deal with other minor technical details here.

All parts of the Y25 chassis, such as bushings and pins in the brake part, are hardened from the Rs variant and, in contrast to the previously used 26-2.8 chassis they enable a reduction in the number of maintenance interventions and, last but not least, repairs in wagons.

The disadvantage of the Y25 chassis is the higher guiding force on the wheelset in the curve. Due to the way the wheelset is guided, there is more wear on the wheelset into the rim. The already mentioned Na 67 group cars, which were imported from Romania and had a Y25Cs chassis and 409 wheelsets, were parked en masse. At the end of 1996, České dráhy had 1,119 of these wagons in its fleet. These vehicles began to show defects in the chassis. These were mainly cracks in the frame, the cause of which was poorly made welds. For this reason, parts of the cars were replaced at the time. Other cars showed only partial shortcomings and, for example, cars with a Y25Cs chassis and a reinforced Rs type were described as operationally reliable.

Ypsilon chassis was further developed, especially in France. From the Y25 chassis, they were further developed, modified and improved. Now we can meet, for example, the chassis Y27 or Y33. This is due to the fact that nowadays trains on the railway reach higher speeds. Therefore, technical and design parameters are further developed. In France, for example, a steel frame is used instead of a welded frame. Frames without fronts are also used, which are only equipped with internal braking. Another modern type of ypsilon chassis is the Y25Lss, whose manufacturer is Vagonka Poprad. Its front is tubular and is equipped with, among other things, two-disc brake units from DAKO, internal brake pads and a cylinder 8.

The Y25 chassis can certainly be described as legendary. Although developed at the turn of the 1960s and 1970s, they are the most widely used chassis to date across Europe - from Scandinavia to the Balkans.


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