The bogie is a key component of any tram: as noted by Belarusian manufacturer BKM Holding, bogies account for almost half of a vehicle’s production cost. This is why possessing an in-house bogie design and domestic manufacturing capability is a matter of sovereignty for any tram builder. In recent years, BKM Holding has been expanding its tram production in response to increased demand from Russia. A key milestone for the company has been the launch of completely low-floor tram models and, consequently, the development of proprietary running gear solutions.
In an exclusive interview with ROLLINGSTOCK, BKM Holding’s Deputy General Director for Innovation Development, Oleg Bytsko, details the bogies developed by the company.
Oleg Bytsko, Deputy General Director for Innovation Development at BKM Holding. Source: BKM Holding
Mr Bytsko, in 2011 BKM Holding received a patent for a low-floor motorised swivel bogie. Is the current bogie based on this patent, or has it been improved?
No, it has practically nothing to do with our current bogie design, which is produced in series and used on fully low-floor trams. That earlier bogie did not allow for a 100% low-floor configuration in the passenger area for standing passengers, and there was still a step above it. Therefore, the 843 platform fitted with that bogie offered 70% low-floor area for standing passengers (referring to BKM-84300M trams supplied to Minsk, Kazan, Saint Petersburg and other cities between 2008 and 2014 – Ed.).
Has the new technology been patented?
We returned to tram development only recently, in 2022, when demand for trams in Russia increased and we realised that the market would be sufficient for us, too. Against this backdrop, we took on the development of new tram vehicles which required 100% low-floor interiors. At present, BKM Holding has not patented its new tram bogie solutions.
Did you take into account experience from the Metelitsa trams (V85600M), which BKM Holding had previously produced jointly with Stadler?
The bogies used in the Metelitsa trams were of a slightly different design. There was no requirement at the time to create a maximally wide aisle in the area above the bogie to enable a ‘two plus two’ seat layout (two seats on each side of the aisle – Ed.). This allowed for a conventional low-floor bogie featuring the motor and reduction drive mounted externally to the wheelset.
In contrast, our current bogie also has the reduction drive mounted externally to the wheelset, but the motor is positioned within the bogie frame. This became possible once small-diameter motors began to be produced in Russia; these, within existing standards for floor gradient in the passenger area, allow for enough space above the bogie to accommodate such a motor.
Work on the Metelitsa certainly provided some experience (at that time, Mr Bytsko was Head Designer for trolleybuses and trams at Stadler Minsk – Ed.). The colleagues involved in that tram’s development are now working at our scientific and technical production centre. The team that specifically handled the Metelitsa bogie now works at Stadler.
Does BKM Holding’s portfolio include a non-swivel low-floor tram bogie?
One example is the T856 tram project — our three-car tram manufactured in 2024 and sent to Nizhny Novgorod, where it underwent acceptance testing. It is equipped with three bogies of a unified design: all are motorised, and the central bogie located beneath the middle section is non-swivel, although it is mounted to the body via the same kingpin used in the swivel bogies. The only distinction is that its rotation is limited by special buffers, since in this layout, used in the T856 tram, the middle bogie cannot be a swivel type in order to ensure stable motion.
The T856 MiNiN tram undergoing testing in Nizhny Novgorod. Source: Belka_NN/transphoto
What is the minimum curve radius traversable by BKM Holding’s low-floor bogies?
The minimum curve radius is determined not by the bogie, but by the carbody design. In designing the body, we took into account that some tram networks in Russia feature curves with a radius of just 14 metres. Accordingly, the body was designed so that the bogies could turn at an angle sufficient for the tram to negotiate such curves.
How many motors are fitted per bogie, and what is their rated power output?
A bogie is fitted with two motors, each rated at 72 kW. At the same time, we are currently working with our Belarusian supplier to produce a motor rated at 75 kW, in line with the requirements of one of our projects. Nevertheless, the existing 72 kW motor provides the required acceleration time — no more than 11 seconds to reach 40 km/h — for both single-unit trams with four motors and articulated three-car vehicles fitted with six motors.
What proportion of the bogie’s components are from Belarus and what from Russia?
We haven’t calculated the exact percentage of components by origin. Let me explain why. If the proportions are calculated by item quantity, it would be meaningless. Calculating by value is also of limited use, as prices are unfortunately on the rise. Moreover, different materials and components increase in cost at different rates: for example, metal may become more expensive, as may various raw materials. Prices for purchased units also vary depending on exchange rates for the Russian and Belarusian rouble. So overall, these are constantly shifting figures that aren’t especially informative.
In terms of key components, all bogie frames and metal structures are currently manufactured in Belarus. Our principal motor suppliers are Russian, although equivalent motors have now also been developed by Belarusian manufacturer Mogilevliftmash. The first four of these motors have been fitted to a tram for Minsk, where they are currently undergoing trial operation under real-world conditions. Should any issues arise, the motors will be refined and serial production will then be launched. The eventual supplier will be whichever company wins the relevant competitive tender — we procure all equipment for our vehicles on a tender basis.
The low-floor T811 tram in Minsk. Source: tralik_v_stepyanku/transphoto
The reduction drive is also manufactured in Belarus, although the main parts for its assembly — gears and housings — may come from various enterprises both in Belarus and in Russia. The choice depends on current conditions: in terms of price and quality, we may opt for either a Russian or Belarusian manufacturer.
We procure wheels from Russia, as production has not been established in Belarus. Hydraulic dampers are Belarusian-made, while suspension dampers come from Russia. The bogie design does not include any cast parts — all elements are fabricated using welded construction.
The situation is similar for the braking system. For magnetic track brakes, we have both a Russian supplier and a Belarusian one. As magnetic track brakes from European manufacturers have become unavailable to us, we have developed technical documentation jointly with the V. I. Kozlov Minsk Electrotechnical Plant. It has already launched serial production of these brakes.
As far as mechanical brakes are concerned, our primary supplier is currently Russian. However, we have already developed engineering documentation and completed bench testing for an in-house brake model. In-vehicle testing is planned shortly, after which a decision will be taken on launching serial production. Again, we plan to retain versatility in choosing brake suppliers.
What are the key advantages of BKM Holding’s bogie over competitors’?
I would emphasise our success in fulfilling the design objective — enabling the manufacture of a tram interior allowing for a ‘two plus one’ seating layout (two seats on one side, one on the other, with a central aisle – Ed.). In other words, we ensured that both passengers and fare collectors can comfortably move through the area above the bogie.
Under the previously mentioned ‘two plus two’ configuration, the space between seats is barely over half a metre. Two large people — and, unfortunately, that now accounts for the majority — cannot pass each other without difficulty. Our bogie has enabled clearance in the area between the wheels and widened the aisle.
Today, we manufacture trams in both ‘two plus one’ and ‘two plus two’ layouts, depending on customer requirements. This flexibility in configuration is, I believe, one of the principal advantages of our bogie.
What are BKM Holding’s short-term plans for developing tram bogies and their production?
There is always room for improvement. Analysis of the needs of passengers — including the elderly, mobility-impaired individuals, and those with prams or bicycles — shows a need to increase standing area while maximising seating in the low-floor zone. To achieve this, we must minimise raised platforms over the bogie. This is, of course, simpler to implement on articulated trams with non-swivelling bogies. With swivelling bogies, the challenge is greater, but viable solutions do exist. This is the direction in which we are currently moving.
Interview by Sergey Belov
