Siemens Combino Budapest

Or a tramcar-purchasing in the engineering perspective...

By the end of 2003, it seemed that the final color scheme and design was fixed for the new Combino Budapest trams. Design drawings appeared. The new Combinos, derived from the models made for Düsseldorf, would receive a front with a gopher's face:
Source: BKV
According to the design drawings on the BKV homepage, I started to redraw one of Hamster's photos from Düsseldorf, see the result below:

Fate struck again: cracks have been found on a Combino, a car from Freiburg which was on a testing in the Czech Republic. The problem is quite big: this time the roof structure cracked. Due to the tonnes of electric equipment is on the roof, it threatens the passenger room from falling in. All Combinos of the World with a running performance of more than 120 000 kilometres were withdrawn from service to be checked. News exposed that a safety modulus of a double load was skipped at the time of dimensioning the aluminium structure, so it can stand only the half of the neccessary load! It is no wonder that fatigue cracks showed up on various parts of the trams.

It became quite clear that Siemens has to deliver a completely newly designed tram for Budapest. Knowing that Siemens is well out of contract terms and the rival companies have also many problems with their own models, BKV has not resiled the contract - Siemens has to pay a large amount of penalty due to the late (by now we already know that BKV is going to purchase additional Volvo articulated buses with this help). Now, what shall Siemens offer? Due to its tramcar manufacturing is mainly based on the former DUEWAG factory (Krefeld-Uerdingen, Germany) and partly on the SGP in Graz (Austria), they have a large selection:

DUEWAG has been on the low-floor market since 1990, from the beginning. It has built these cubic shape tramcars for Kassel for the first time, but this is not the solution for Budapest as we need 100 percent low-floor cars, this car has middle height floor above the bogies on both ends.

This is the same reason why the models for Karlsruhe (left) and the Mannheim region (right), which are also developed from the Kassel model, are not adaptable.

But there was a branch of the family tree, a 100 percent low floor tram made for Frankfurt, although they wanted to sell them because of the many early problems: namely to Budapest. Outgrown these failures (about which I don't know too much, so if you know it, please send me an !) they remained here in service. Its structure is quite interesting: it is a three-section articulated car, but it has only three bogies, and they are all underneath the sections, not the articulations. This requires the two-axle car sections to be coupled together by springs enabling them to go in different directions in curves, then make them follow each other in the same direction when going straight again. Going in the same curve, the car sections may move in different directions at the same time, making the car go winding like a snake. But the rival firm has built a same kind of tramcar:

AEG-MAN (later ADtranz) has built same looking cars in three and four section livery (on the picture you can see a car from Nuremberg). Due to their snake-like movements they have a nickname -as I heard- Sambawagen (a car dancing samba). Their movement is similar to the KT4's, as the first, the third (and on the coming Budapest version the fifth) car section turns into the curve, behind them the second, the fourth (and on the Budapest version the sixth) car section starts to turn to the opposite direction of the curve, because it follows the swinging back of the car section ahead. And a fact we shouldn't pass by: Siemens obtained the licence of these cars! Now we have the solution: they will build a new type for Budapest using this technology!
Source: BKV
As the four-section trams in Nuremberg and Munich are built up of two short, two-section parts coupled together (with a double length articulation in the middle to enable wider range to move sideways as it was a normal coupling between two independent cars), the required tram for the Budapest Grand Boulevard lines 4 and 6 with a length of 54 meters (the longest tramcar of the World) will be built up of six sections (3x2 sections), see the drawing above.

The short two-section parts are coupled together by a double length articulation, as seen on the picture. Oh yes, the passenger tunnel is a bit narrow.
Source: BKV
Two design drawings appeared on the BKV homepage again. Unfortunately, this time they didn't let the people to vote which design they prefer. My humble opinion says the one on the right is better (at least because the livery on the left can be already seen in other towns like Bern, Nordhausen, Erfurt etc.). They also made a new, constrained name for the new type: Siemens Combino Supra Budapest NF 12B. Okay, if they are like that, I'll tell them its short name should be SCSBPNF12B, no doubt! :-)


I don't know if Siemens is still undertaking to bring a test car to Budapest, but if they are, they can only bring the normal gauge, bi-directional cars from Frankfurt or Berlin (on the picture you can see a one-directional car from Berlin). But only the Berlin cars are avaible to couple two cars together in passenger traffic (this makes their capacity similar to those on the Budapest lines 4 and 6). The point is that the Berlin cars are not made by Siemens but the rival Bombardier. :-)) If they bring cars from Frankfurt, they won't carry passengers because of the half capacity.

If I know well, one of the conditions of the contract is to bring a well-tried type, not a prototype. However, because of the door- and seat arrangement, the running gear (the bogies) are going to be a novelty. To see why, let's take a look at the running gear of the original tram, the AEG-MAN one, in details!
Source: Tramvaje
There is a running- and a powered axle in each bogie, so the axle arrangement of the three-section cars is 1A'+1A'+1A', and of the four-section cars is 1A'+1A'+1A'+1A'. The two wheels of the powered axle are driven by a common motor installed in the length, on one side, coupling the two wheels together by a coupling axle (yellow part on the picture).

The motor is installed underneath the side seats. But this drive arrangement can not be adopted for the Budapest trams, because 8 axles are have to be driven from the total twelve...

Layout of the original drive arrangement (left) and a possible layout with two motors (right)

...and because the doors are facing each other, the two motors can not be installed on the two ends of the bogie (see the layout on the right). Unfortunately, due to the Grand Boulevard Line, since the reconstruction, has having stations with platforms on both left- and right sides, inordinately, you shouldn't put the doors on the two sides far from each other. So they have to find another solution.

Source: Tramvaje
For example, they could install the wheel-hub motors of the Frankfurt cars. Now, they seem to be working well, even, together with the company ELIN, they have installed a newer version of them into...

...the ULF's (Ultra Low Floor tramcar) in Vienna, Austria. A small problem: this is a Siemens invention, if they build this one into the Budapest cars, Kiepe, the other firm of the winner Siemens-Kiepe consortium stays out. Kiepe had made the electric equipment of the conventional Combino cars. The easiest way is not to invent a brand new electric and drive equipment for the new trams...
Source: Tramvaje
...but to install the conventional Combino equipment. This is developed from the good old DÜWAG monomotor drive from the sixties. You can see this kind of drive for example underneath the older DT-8 cars of Stuttgart:

A motor is installed in the length, in the middle of the bogie, between the two axles, with a drive on both ends, into a bevel-drive house (the box in the middle of the picture is this house). The two bevel-drives move a tube-axle on each end. These tube-axles are connected to the wheel axles by rubber rings (on the older models for example type E1 of Vienna and Miskolc or TW 6000 of Hannover and Budapest) or sandwich-springs (like on the picture, these are rubber and metal plates above each other). The smaller, more compact livery of this was developed for the conventional Combino tramcars. Due to the lack of space, the four wheels of the running gear is driven by two, 100 kW (136 HP) strong, longitudinal motors on each side, each motor drives two wheels on one side, the wheels on the opposite side are independent.
Source: Tramvaje
One problem remains: the running gear of the conventional Combinos are not bogies, they don't turn under the car bodies. It works as short two-axle cars, with a middle section without wheels hanging on them (for example the late "Schüttelrutsche" in Germany). To enable the car doing its "samba" movements the running gear actually has to turn under the car body (the running gear has to work as a real bogie), or else the car would stuck in the curves and derail. I hope this novelty will not mean serious modifications - and more problems in maintenance.

One thing is certain though: interior will be even tighter at the running gears because now the new running gears (bogies) has to turn under the car body while the conventional Combino running gear has been running in the same direction as the car body.

Now, that's enough for a while about how our Combino derives from another Combino through a Sambawagen. Let's hope they will work well. Then, three-section Combinos might relieve single car ICS articulated trams, and four-section Combinos might relieve the three car UV trams in the future. But until then, a long-long time will pass us by...

Text and photos by András Báti, except where otherwise mentioned (C) 2003-2005

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