Category Archives: Swiss Railways and Tramways

The Modern Tramway – February 1951 – Traction Motor Trends in 1951 – and beyond

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The featured image for this article is a line drawing of a drive system from a Hamburg Metro Car, an SKF DT4. [5] … AC traction motors (commonly induction motors) are the standard for modern trams, replacing older DC motors to provide higher efficiency, better reliability, and reduced maintenance. These motors, often running at 60–200 kW, power the bogies and enable regenerative braking to feed energy back into the overhead line. They are controlled by variable-frequency inverters for smooth acceleration.

The Modern Tramway of February 1951 carried an article by ‘Eltee’ entitled ‘Traction Motor Trends’ about the recent changes in electric motors in trams. [1: p33-34]

“The present trend towards the use of lightweight high-speed electric motors for traction purposes, a trend exemplified at its best by the motors used in in the P.C.C. cars in America, and those of similar design now being introduced at Blackpool and and Glasgow and on the Continent, justifiably prompts the query as to why motors were not, in the past, built as they are today. There are actually several reasons for this, some highly technical, but one of the more important is that the need for efficient ventilation of motors was not sufficiently appreciated in the early days.

“When a motor is running and current is passing through its conductors these conductors are heated by the passage of current, just as are the conductors of an electric stove though much less so. The power represented by this heat is lost to the motor, and called the ‘copper loss’. Another source of loss is the rotation of the armature in the motor magnetic field; the alternating magnetism through the armature caused by its rotation brings about power losses in armature iron, which also appear as heat. In running, then, the motor gets heated, and if there were no means of dissipating this heat the motor would get hotter and hotter until something melted.

“In practice this does not happen, as the motor casing is in contact with the air around it, and when the casing is hot it loses heat to this air, doing so all the more readily when the car it is driving is moving and there is a certain amount of draught. Many years ago this was the only way of cooling the tramway motor, hence a large motor had to be used simply to ensure that there was enough casing area to dissipate the heat generated. Some additional armature cooling was given by the provision of axial ducts in the armature, aided by a few radial ducts. In this way some slight fanning action was given by the moving armature, swirling the air in the motor casing and conveying the heat from the armature more readily to the outside casing for dissipation into the atmosphere.

“A later development introduced what is now known as ‘series ventilation’, the self-ventilated motor being introduced about 1910. In such a motor a fan is mounted on the non-commutator end of the armature, and two sets of openings are made in the same end of the motor casing. The fan draws air through the armature axial ducts when the motor is running and expels it through one of the casing openings; this assists to keep the armature cool. This air, in the first place, is drawn in through the other set of openings and over the field coils before turning round and entering the armature ducts; in this way the field also is kept cool, but the ventilation of the armature suffers because the air is already somewhat warmed by its passage over the field coils.

“A further development, common from about 1920 onwards, is known as ‘parallel ventilation’, in which there are two parallel air streams through the motor. A twin fan is fitted to the non-commutator end of the armature, and openings made in both ends of the motor casing. The fan draws a stream of cool air over the commutator, round the armature surface and over the field coils before expelling it. The other half of the fan draws an air stream under the commutator and through the armature axial ducts, thus keeping the interior of the armature cool and dissipating most of the iron losses effectively.

“With a motor as efficiently ventilated as this it is possible to ‘force’ the motor more without its getting too hot; that is, in more technical language, a motor can have a higher rated power. Consideration of the above method of ventilation readily shows that if the motor armature rotates more quickly the attached fan will draw more air through it, ventilate it even more thoroughly, and permit even more ‘forcing’ by the passage of greater currents. This, in essence, explains the present trend towards motors of high rotational speed; the efficient ventilation possible on such motors permits more power to be passed through them than through motors of similar size with less effective ventilation.

“The above being understood, two further points are worthy of emphasis. One is that the greatest losses occur in a motor when it is starting and running slowly; the best ventilation occurs when it is running quickly. Cars on a town route will thus need bigger motors than similar cars on an interurban route on which there is a lot of free running, providing their maximum speeds are equal. The second point is that, if motors have been used on a service on which their capabilities are being fully employed the gear ratio must not be altered, because, although the speed of the cars can thereby be improved, such a measure will not only increase the currents passed through the motor (for more power will be required from the motor) but will also decrease the average speed of rotation of the motor. resulting increased “losses” and impaired ventilation will both tend to raise the operating temperature of the motor. and so reduce its life, unless it was known that hitherto it had been used well below its capacity and was operating at relatively low temperatures.” [1: p33-34]

Since ‘Eltee’ was writing at the beginning of the 1950s, much has changed!

Improvements in the ventilation of tramcar electric motors since 1950 have centred on a move away from traditional forced-air cooling in direct current (DC) motors to advanced, sealed, and integrated systems used with modern AC traction, enhancing reliability and reducing maintenance. [2][3]

Modern three-phase AC motors allow for lighter, more compact, and more powerful motors. These motors are often less sensitive to heat and easier to cool than older designs. [2][3]

Modern tram design integrates motors directly into the bogies, with ventilation systems designed as part of the overall low-floor, compact carriage architecture, ensuring better cooling airflow in restricted spaces. [3]

Many modern motors are now completely enclosed, utilizing improved heat sinking and specialized cooling fan designs rather than drawing in outside air, reducing the impact of dust and water on electrical components. [2][3]

The use of GTO-inverters and modern power electronics reduces motor heat generation compared to older resistor-controlled DC motors, reducing the load on ventilation systems. [2][3]

Improved insulation materials allow motors to operate safely at higher temperatures, reducing the strain on the cooling systems and improving longevity. [2][3]

Modern electric trams utilize motors to generate electricity during braking, returning power to the grid or charging on-board batteries/supercapacitors. The use of battery-power and on-board storage can allow trams to pass through city centres or other sensitive areas without overhead wires. [3][4]

Electric motors are ideal for rapid urban transport because their higher torque at low speeds allows speedy departures from stops on a network. It also allows tramcars to handle hilly terrain better than internal combustion engines.

Electric motors are roughly 90% efficient at converting energy into motion. In contrast, diesel engines lose about 60-70% of fuel energy as heat. [4]

Additionally, unlike internal combustion engined vehicles that consume fuel while stopped, electric trams use virtually no power when stationary. [4]

AC motors have been shown to improve reliability and decrease downtime compared to traditional DC motors. But they have significantly lower maintenance needs than internal combustion engines, having far fewer moving parts and not needing oil changes, spark plugs, filters, and complex exhaust systems. The high torque of electric motors at low speeds eliminates the need for heavy, expensive multi-stage gearboxes common in internal combustion engined vehicles. [4]

Trams typically have a service life of about 30 years, roughly double that of diesel-powered buses. They typically produce no local pollutants like nitrogen oxides or particulates, which is critical for city air quality and meeting climate targets. Electric propulsion is significantly quieter than internal combustion engines, reducing noise pollution in densely populated areas. In addition, electricity can be generated from various sources, including renewable energy (wind, solar, hydro), making the system future-proof as the power grid decarbonizes. [4]

Increasingly in an urban environment public transport is heading underground. Because they emit no exhaust fumes, electric trams can safely operate in tunnels and underground stations where diesel engines cannot.

Internal flexibility is increased as the need for bulky and heavy engines and fuel tanks is eliminated. The net gain is a more friendly user experience, faster loading and unloading at stops and increased passenger capacity. [4]

It is not surprising that many cities around the UK, and across the world, are seeking to reintroduce trams and to increase the size of their networks.

References

  1. ‘Eltee’; Traction Motor Trends; in The Modern Tramway Volume 14 No. 158; The Tramway and Light Railway League, February 1951, p33-34.
  2. https://en.wikipedia.org/wiki/Electric_locomotive, accessed on 12th May 2026.
  3. https://en.wikipedia.org/wiki/History_of_trams, accessed on 12th May 2026.
  4. https://medium.com/@blaisekelly/why-trams-are-cheaper-than-buses-6d929192624a, accessed on 12th May 2026.
  5. https://evolution.skf.com/new-drive-systems-for-mass-transit, accessed on 12th May 2026.

Articulated Tramcars for Basel & Zurich – Modern Tramway, June 1962.

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Modern Tramway and Light Railway Review, June 1962 carried an article based on notes by H.J. Bertschmann, G.A. Meier and M. Frei about then new articulated trams in these two Swiss cities. [1]

Both the Basler Verkehrs-Betriebe and the Verkehrsbetriebe der Stadt Zürich had taken delivery, in the months prior to the article being written, of the first prototypes of a new design of articulated tramcar. The design was a new departure, a double-articulated tram on three trucks. Earlier models of articulated cars had  two sections on two or three trucks, or three sections on two or four trucks, but never before three sections on three trucks.

“Wages costs represent a very high pro- portion of the total costs in the operation of public transport, and in both Basel and Zürich reach[ed] 80 per cent of the total expenditure. Economy in staff [was] therefore the only way in which undertakings [could] remain solvent, and the rapid increase in traffic oblige[d] transport undertakings to use high-capacity vehicles in order to minimise utilisation of the road surface. The development of bogie cars was the first step in this direction, and the delivery of the first articulated cars carries this a stage further.” [1: p19]

The interior of Zürich Tramcar No. 1801. Modern Tramway commented in 1962.”Its clean lines are very attractive, and the styling is in accord with the latest Swiss designs. The Basel cars differ only in minor details such as the arrangement of grab-rails and in the provision of upholstered seats. Even in 1962, Zürich trams have hard seats of moulded reinforced plastic; their riding is so smooth that upholstery is unnecessary! © Verkehrsbetriebe der Stadt Zürich. [1: p19]
Zurich Tram Car No. 1801 sits outside Irchel Depot © Ernst B. Leutwiler Verlag. Entrances to the tram were at either end. Egress was via the two central doors. Number 1801 was built in 1961 as a prototype for the large batch of, what Zurich would call, Mirages that came later in the 1960s. It was scrapped in December 1999. [3]

The very different technical requirements of the Swiss urban transport undertakings had often hindered the development of a Swiss standard tramcar, one of the difficulties was caused by differences in the topography of the towns.

“This … led to a unified effort by the Basel and Zürich undertakings, the two largest tram- ways in Switzerland, to design an articulated car whose basic design was suitable for both undertakings. Whilst a classical (by German standards) two-section single-articulated six-axle car was built for Zürich by SWS (Schlieren), the co-operation between the two systems to find the most advantageous design resulted in an order for three articulated cars, two for the BVB (Basel) and one for the VBZ (Zurich), being placed with SIG (Neuhausen). SIG conceived a new style of construction, departing from the customary articulation over the central bogie (known as a Jacobs bogie) in favour of a short middle section on a two-axle non-rigid truck with an articulation at each end.

There [we]re so many common features in the design for both BVB and VBZ that practically the only differences [we]re in the number of motors and their electrical connections. Basel cars [had] four motors totalling 264 kW, whilst Zürich cars [had] six motors rated at a total of 396 kW. Motor bogie wheels ha[d] a diameter of 720 mm against the 660 mm of the Basel middle bogie wheels. Whilst the Basel cars [would] normally each haul a bogie trailer and the Zürich prototype car will also do this, the production batch of Zürich cars [would] run in multiple-unit pairs, and … (like Basel) have only two power trucks. Zürich has still to decide whether the two leading trucks will be motored, as distinct from the end trucks as at Basel. By confining the differences to these features (apart from minor differences in interior styling), the cars [could] achieve the maximum economy whilst ensuring the best use of the adhesion weight. By means of special mechanisms, it was possible to arrange the axle loadings so that the load on the driving axles was the same in both the four-motor and six-motor cars. Variations in the axle-load on the middle truck induce[d] horizontal forces in the upper part of the articulations; these induce[d] turning movements in the vertical plane, with consequent transfer of load between the outer and inner trucks. As a result of this design, the car [was] better able to start from rest on hills. [1: p19-21]

The advantages of the new design were:

  • The middle truck is not under the articulation mechanisms – so maintenance is much easier.
  • Rotation over each of the two mechanisms is half of that for one mechanism.
  • The body did not obstruct the drivers view of the exit doors which are in the middle section of the tram.
  • Double articulation permits wider front and end designs which allows doors to be built in the parallel sides of the tram.
  • A minimising of internal obstructions for passengers was achieved by the lesser amount of articulation required.
These two diagrams enable a comparison to be made between the conventional articulated car (left) and the new Swiss double-articulated design. The left-hand diagram shows the extensive end-tapering necessary to prevent overhang, whilst the right-hand diagram shows how “squarer” ends are possible and that much less relative movement takes place at the articulations, © Der Stadtverkehr. [1: p188]
Plan and elevation of Basel  Tramcar No. 601. Apart from the livery, the external appearance of the Zürich car differs mainly in the addition of a front coupler, © Der Stadtverkehr. [1: p189]
Basel Articulated Tram No. 601 on Aeschenplatz in 1981, © Henrik Boye and used here by kind permission of the photographer. This tram survived in service until 1991. Its last journey in service was on 5th May 1991 and it was written off on 13th June 1991. [2][4]

Trams travelled at a maximum speed of 60km/h and had a capacity of 42 seated and 123 standing. The empty car weighed 28.3 tonnes. The significant dimensions of the tramcars were:

  • Overall length between couplings: 20.45m
  • Length of body: 19.7m
  • Height of roof over rails: 3.385m
  • Width: 2.2m
  • Distances between king-pins: 7.0m
  • Overhangs: 2.85m
  • Wheelbase of motorised truck: 1.86m
  • Wheelbase of non-motorised truck: 1.7m

The article describes the trucks, braking systems and control systems as follows:

“The motor trucks are swing-link trucks with outside frames and torsion-bar springing. The springing of the torsion bar and the swing-links is combined into a single springing system, and this contributes considerably to noise reduction, in conjunction with the resilient wheels. The longitudinally-mounted motors are held by a three-point suspension to the truck frames, using rubber inserts.

The braking system: … The service brake is rheostatic, augmented with an air-operated disc-brake. A Charmilles brake handle is fitted under the controller wheel (a Volkswagen steering-wheel), … the air brake automatically supplements the electrical brake as the regenerative current dies out, and excessive braking through combined electric and air braking applications is eliminated. In an emergency, the braking effort can be supplemented with magnetic brakes. The parking brake is a hydro-mechanical hand brake. An Electro-pneumatic valve proportions the application of air to the trailer and (on the Basel cars) to the un-motored truck.

The control system has 22 running notches, of which the last three are field-weakening notches; there are 23 notches for rheostatic braking and a 24th emergency notch for magnetic braking in addition. The motors are connected in series pairs, each motor operating at half-voltage, and every effort has been made to keep the number of power cables crossing an articulation to a minimum.” [1: p190-191]

The truck design adopted for the, then, new Basel and Zurich cars, © Der Stadtverkehr. [1: p190]
This schematic drawing illustrates the, then, ingenious link mechanisms at the articulations whereby the load was distributed in the most efficient manner. The upper diagram shows an elevation of the central section, and the two lower diagrams show plans of the car on a curve and on straight track, © Der Stadtverkehr. [1: p190]

The Modern Tramway Journal also reported on a number of other features:

“The exit doors incorporate a device similar to that on the Stuttgart articulated cars. They are operated by the passengers through a push-button, and the opening of a light inner door by the passenger in order to gain access to the step holds the main doors open. The other function of the inner door is to prevent the entry of passengers at the exit doors. In Zürich, passengers would press the push-button to signal to the conductor to open the doors, whilst Basel had intended that passengers should open the doors themselves. However, as Basel experienced some confusion with this arrangement, they changed over to the Zürich system.

Particularly interesting features of the new cars include a “Hesomat” indicator blind, driven by an electric motor. The driver merely presses a “tens” button and a “second digit” button for the code number of the desired destination, and this is automatically set-up. Another innovation is the point-changing button enabling the driver to simulate a “power” signal whilst coasting past the detector. To prevent the current taken by auxiliaries causing a false “power” signal, a push-button in the centre of the controller wheel can cut off all auxiliary power as the detector is passed.

The Zürich undertaking needs new cars urgently and it is hoped that the number of articulated cars will ultimately rise to 200; they are intended to be the basic unit for the planned Tiefbahn (subway) services. The Basel plans are less ambitious for the present, but they hope to operate route 6 entirely by these cars at some date in the future. This route, from Allschwil to the German border at Riehen, is one of the fastest urban routes in Switzerland, and these cars should be particularly suitable.” [1:p191]

In addition to the external jack-knife doors, the exits have a single leaf internal door. The action of the passenger in holding this open keeps the main doors open, and it also serves as a handrail. Its main purpose, however, is to deter passengers from entering by the exits, © Basler
Verkehrs-Betriebe.[1: p191]

Ultimately, tram No. 1801 was a success as a prototype in Zurich. A series of these vehicles were purchased later in the 1960s and were called ‘Mirages’. [4] An online acquaintance tells me that a number of these trams were later sold to the city of Vinnytsia in Ukraine. Details can be found here, [6] and in the YouTube video below. [7]

Ukraine passes trams to Vinnytsia. [7]

Tram No. 601 and its partner were less of a success in Basel. As a result, the two trams ordered by Basel were not followed by a larger order. They remained the only Basel trams of their specific type. [5] Basel did purchase further articulated trams but from different a different source.

References

  1. H.J. Bertschmann, G.A. Meier & M. Frei; New Articulated Tramcars for Basel and Zurich; in Modern Tramway, Light Railway Transport League and Ian Allan, Hampton Court, Surrey, June 2022, p187-191.
  2. https://en.sporvognsrejser.dk/foto/s/basel-articulated-tram-601-on-aeschenplatz-1981.jpg, accessed on 2nd August 2023.
  3. https://en.sporvognsrejser.dk/foto/postcard-zurich-articulated-tram-1801-at-the-depot-tramdepot-irchel-1975, accessed on 2nd August 2023.
  4. https://transphoto.org/vehicle/276178/?lang=et, accessed on 3rd August 2023.
  5. https://ba.e-pics.ethz.ch/catalog/ETHBIB.Bildarchiv/r/690998/viewmode=infoview, accessed on 3rd August 2023.
  6. https://en.m.wikipedia.org/wiki/Trams_in_Vinnytsia, accessed on 10th August 2023.
  7. https://www.youtube.com/watch?v=Gh7sMfSNK08, accessed on 10th August 2023.

The Schynige Platte Railway, Interlaken, Switzerland

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My wife and I visited Switzerland in 2004 and enjoyed travelling extensively by train. One little railway that we enjoyed was the Schynige Platte Railway near Interlaken. The track gauge for this line is 800mm. Trains leave Wilderwil station and run alongside the Berner Oberland-Bahan (BOB) for a third of a mile (0.5km) before turning away, crossing the River Lütschine and climbing the side of the valley. Forest eventually gives way to alpine pasture and views across Lake Thun and Lake Brienz. When the weather is good there are excellent views of the Eiger, Monch and Jungfrau as the train climbs to the terminus at Schynige Platte. In 4.5 miles (7.25km) the line rises 4,659ft (1,420m).[1] The route is shown on the map below.[2]

Close to the station there are a botanical garden,[3] a hotel and a restaurant.

Technical Details: Track-gauge 800mm. Power: 1500 volt DC overhead. Rack: Riggenbach. Maximum Gradient: 1 in 4 (25%). The line’s depot and workshops are located adjacent to Wilderswil Station.

“The line is owned by the Berner Oberland-Bahnen AG, a company that also owns the Berner Oberland-Bahn. Through that company it is part of the Allianz – Jungfrau Top of Europe marketing alliance, which also includes the separately owned Wengernalpbahn, Jungfraubahn, Bergbahn Lauterbrunnen–Mürren, Harderbahn, and Firstbahn.” [1]

Photographs: Except where referenced otherwise, the photographs below were taken by us in 2004. My digital camera in those days was not of the same standard as I am used to now.

Schynige Platte Zahnradbahn.jpg – Wikimedia Commons.[4]

Taken at Schynige Platte Station by Uve Mockel in 2004.[5]

References

  1. Wikipedia, Schynige Platte Railway; https://en.wikipedia.org/wiki/Schynige_Platte_RailwayRailway, accessed on 21st April 2018.
  2. MySwisAlps.com; https://www.myswissalps.com/schynigeplatte/gettingthere
  3. Schynige Platte Alpine Garden; http://www.alpengarten.ch/en.
  4. Wikimedia Commons – Schynige Platte Zahnradbahn.jpg; https://commons.m.wikimedia.org/wiki/File:Schynige_Platte_Zahnradbahn.jpg, accessed on 21st April 2018.
  5. http://www.familie-moeckel.net/Builder/sonstiges/1280/Zahnradbahn1280.jpg

The Rochers-de-Naye Line

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My wife and I travelled this line in 2004. The views were spectacular and the weather wasn’t bad at all! My camera, in those days, was not able to produce high resolution photos. But these give a very good impression of the line and the views from the top. The first image is a map of the line. Trains depart from Montreux station and climb steeply on a rack railway, first in tunnel, and then through the village of Gilon (300m above Montreux) which was historically the start of the steam railway when opened in 1892. The line is known as the MGN (Montreux, Gilon, Rochers-de-Naye) Railway.

242T66 on the Passions Metrique et Etroite Forum has pointed out to me that in 2004 I was fortunate to enjoy a ride on a steam driven service on the higher reaches of the line (pictures below). It was apparently only for a few summer seasons that the steam service was operated on this line between Caux and Rocher-de-Naye.

242T66 comments that the MGN line was electrified since 1938. It was the early 1990s when the former SLM company at Winterthur built a few modern oil fired steam locomotives for the Brienz Rothorn Bahn and for a couple of Austrian rack railways (Schneeberg and Schafberg Bahnen). At that time, they also built one for the MGN line.

This was H2/3 n° 1 Rochers-de-Naye which features below. A nostalgic steam train was in operation for just a few years before the steam loco was eventually sold to the Brienz Rothorn Bahn.

The next few images show the views from the top of the line.

And finally a few images at the bottom of the line, in Montreux

The Brienz-Rothorn Bahn, Switzerland

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My wife and I travelled this line in 2004. The views were spectacular and the weather was in our favour! My camera, in those days, was not able to produce high resolution photos. But these give a very good impression of the line and the views from the top. The first image is a map of the line.

242T66 on the Forum Passions Metrique et Etroite, very kindly, pointed out that the pictures that I originally posted on this blog came from another Rack Railway – the MGN (Montreux, Gilon, Rochers-de-Naye) Railway. Those have been moved to another blog post (https://rogerfarnworth.wordpress.com/2018/04/16/the-rochers-de-naye-line) and photos from 2004 of the BRB now follow below!

The link below takes you to an excellent video of the line: