Key takeaways
- A 3/5 isn't a number, it's a description: A stands for the fastest speed class, 3/5 for three powered out of five axles.
- No lower-case letter means steam: an e would mean electric, an m an internal combustion engine – A 3/5 has neither.
- The locomotive is historic: it dates from before the electrification of the Swiss network and today only runs as a museum piece.
- Counting axles gets you a rough classification: three large driving wheels plus two small carrying axles at the front.
- Sightings are a matter of dates, not locations – museum steam locomotives run on announced days, not to a regular timetable.
Contents
Fact file
| Vehicle type | Express steam locomotive |
|---|---|
| Railway administration | Swiss Federal Railways (SBB) |
| Classification system | A = highest speed class, 3/5 = three driving axles out of five |
| Wheel arrangement | 2'C – three coupled axles, preceded by a two-axle leading bogie |
| Engine type | Four-cylinder compound locomotive |
| Manufacturer | including the Swiss Locomotive and Machine Works (SLM), Winterthur |
| Current status | Museum stock – no scheduled service in regular operation |
Identifying features
Is this really the class in front of you?
- Three coupled driving wheels of large diameter – typical of an express locomotive
- Leading bogie with two smaller carrying axles ahead of the driving wheels
- No lower-case letter in the designation: A 3/5 without an e or m means steam traction
- Separate tender – the locomotive doesn't carry its own coal and water
- Strikingly long, slender boiler compared with squat freight engines
- Markings in Swiss style with a fraction instead of a four-digit class number
Updated: August 2026 – A locomotive whose name already reveals what it can do: the SBB A 3/5 is an express steam locomotive from the era when Switzerland still moved its long-distance traffic with coal. Today it stands for two things – the era before electrification, and a classification system you can learn in five minutes and then apply across the whole country.
Document historic vehicles properly
Museum sightings are rare and date-dependent. Record them with date, occasion and location while the memory is still fresh.
What is the SBB A 3/5?
The A 3/5 is an express steam locomotive of the Swiss Federal Railways with three powered out of a total of five axles. It was built for heavy, fast passenger service on main lines – the job that electric locomotives would later take over.
As an engine, it belongs to the category of four-cylinder compound locomotives: the steam is used twice, first in high-pressure cylinders, then in low-pressure ones. Around the turn of the century that was the state of the art for economical express engines. The type was built, among others, by the Swiss Locomotive and Machine Works (SLM) in Winterthur, the manufacturer that shaped Swiss traction for decades. Steam locomotive construction in Switzerland is carried on today by Dampflokomotiv- und Maschinenfabrik AG (DLM), which grew out of that same environment.
Important for context: the A 3/5 is today no longer an operational vehicle. Anyone who encounters it does so in a museum context – at a museum, with a heritage society, or on an announced special excursion.
The Swiss classification system in five minutes
German class numbers have to be learned by heart. Swiss designations can be read. That’s the biggest difference between the two systems – and the reason the effort here really pays off.
First capital letter: the speed class
A stands for the fastest category, followed by B, C, D. E marks shunting locomotives, T tractors, X service vehicles. An A right at the front means: built for speed.
Lower-case letter: the type of traction
A lower-case e means electric, a lower-case m internal combustion. If there's no lower-case letter at all, as with A 3/5, it's a steam locomotive.
The fraction: the axle ratio
The numerator equals powered axles, the denominator total axles. 3/5 means: three of five axles are driving axles. With 4/4, all four would be powered.
Roman numeral: the production series
An appended I, II or III distinguishes successive series of the same basic type – for example the Re 4/4 II versus the Re 4/4 I.
With these four rules you can read a Re 4/4 I just as easily as the shunting locomotive Ee 3/3 or the freight locomotive C 5/6. How to approach an unfamiliar system in general is described step by step in the guide to identifying classes.
How to recognise an express steam locomotive in the field
With steam locomotives, the axle arrangement almost always reveals the intended use. Anyone who knows what to look for can tell an express locomotive apart from a freight locomotive without reading a single data panel.
| Feature | Express locomotive like the A 3/5 | Freight locomotive like the C 5/6 |
|---|---|---|
| Driving wheel diameter | large, designed for speed | smaller, designed for tractive effort |
| Number of coupled axles | few (three) | many (five) |
| Carrying axles | leading bogie for smooth running at speed | usually just one leading axle at the front |
| Letter in the name | A (highest speed class) | C (slower class) |
| Typical historical train | heavy express and passenger trains | freight trains, mountain lines |
The trick with wheel diameter
Compare the driving wheels with the height of a person standing next to them. If they reach well above hip height, it's an express locomotive. If they stay below that, think freight first.
Save steam sightings with context
Occasion, weather and route all belong with a sighting of a historic vehicle – log them all in one entry in Traintrack.
Finding and photographing special excursions
With museum vehicles, it isn’t the photo spot that decides success, it’s the date. An A 3/5 doesn’t run on just any Tuesday – it runs when a heritage society or museum lets it. The Blonay–Chamby heritage railway in western Switzerland shows how regularly historic operation can take place.
Research dates before spots
Event calendars of heritage railways and societies are the real source. Only once the date is fixed is it worth searching for a location.
Favour cold weather
Steam becomes visible when it condenses. On cold, damp days you get the full plume; in high summer you often get almost nothing.
Think about wind direction
If the wind is unfavourable, the smoke settles over the whole train. Choose the side so the plume drifts away from the vehicle.
Work from public areas
Tracks and operational railway land are off-limits – even during a special excursion. Platforms, paths and bridges offer plenty of usable angles.
The concrete technique – exposure, shutter speed, handling smoke and backlight – is covered in the guide How to Photograph Steam Trains. Where dates for museum excursions actually get published is shown in the heritage railway guide. And anyone who wants to get involved rather than just photograph will find a starting point in the overview of railway societies in Germany, Austria and Switzerland.
What made an express steam locomotive work operationally
To understand why the A 3/5 looks the way it does, it helps to look at its job. Before electrification, an express locomotive had to do three things at once: deliver consistently high output over long distances, run smoothly enough not to become dangerous at speed, and do so economically with coal and water.
Each of these requirements produces a visible design feature. Large driving wheels keep piston speed within limits at high speed. The leading bogie guides the engine through curves and prevents rough riding. And the compounding of the four-cylinder engine uses the steam twice, which lowers coal consumption per unit of work done.
The separate tender fits the same logic: a locomotive that has to run long distances needs to carry supplies that won’t fit on the engine itself. That’s why tank locomotives without a separate tender are found on local services and shunting duty, not in front of express trains.
Reasoning from feature to task
With historic vehicles it pays to turn the question around: not "which class is this?" but "what was it built for?". Wheel size, axle count and tender type almost always answer that question – and the class follows from there by itself.
Common mix-ups
It points to an A 3/5 if …
- you count three large coupled driving wheels
- there's a two-axle leading bogie in front
- a separate tender is attached
- the markings show a fraction without a lower-case letter
Look more closely if …
- the locomotive is standing in a museum without markings or freshly repainted
- you only see it from the side with the carrying axle hidden
- a similar express locomotive from a private railway is standing next to it
It isn't an A 3/5 if …
- you count five coupled axles – then you're looking at a freight locomotive
- there's a pantograph on the roof
- the designation contains a lower-case letter, such as Ae, Re or Ee
Conclusion
The A 3/5 is two things at once: a specific historic vehicle and the best introductory lesson in the Swiss classification system. Once you understand that A means the speed class, 3/5 the axle ratio, and a missing lower-case letter means steam traction, you can read any Swiss locomotive designation afterwards without looking anything up. For the sighting itself: date beats location, and patience beats luck.
In short
Three large driving wheels, two carrying axles in front, a tender, and a designation without a lower-case letter: that's the A 3/5. Today it's pure museum stock – plannable only via announced dates, not the timetable.
Museum vehicles in your collection
Special excursions, museum days, anniversaries: Traintrack helps you keep track of which historic vehicles you've already seen.
Summary
- The A 3/5 was one of the express steam locomotives the SBB used to haul premium passenger services before widespread electrification.
- The Swiss classification scheme of letter plus fraction gives you the vehicle description directly – no need to know a class list.
- Surviving locomotives are museum vehicles; their runs depend on special excursions, overhauls and the condition of the individual example.
- Anyone wanting to photograph steam plans around dates and weather rather than photo spots alone – cold air makes all the difference in the picture.
Frequently asked questions
What does the designation SBB A 3/5 mean?
It describes the vehicle directly. The capital letter A stands in the Swiss system for the highest speed class, i.e. an express locomotive. The fraction 3/5 indicates that three out of a total of five axles are powered. Unlike German class numbers, the designation is therefore self-explanatory.
How can I tell it's a steam locomotive?
By the missing lower-case letter. In the Swiss scheme, a lower-case e stands for electric traction and a lower-case m for an internal combustion engine. A designation without any such addition – like A 3/5 – marks a steam locomotive. The tender confirms it instantly in the field.
Does the A 3/5 still run today?
Not in regular service. The class dates from before the network's full electrification and was withdrawn from scheduled service long ago. Surviving engines belong to the museum stock and can, at most, be seen at special excursions, anniversaries and museum events. Whether and when a locomotive is operational changes with overhaul deadlines.
What sets the A 3/5 apart from a freight steam locomotive?
Mainly the wheels and the axle arrangement. An express locomotive has few but large driving wheels and a leading bogie for smooth running at high speed. A freight locomotive like the C 5/6 has more, smaller coupled axles – designed for tractive effort on gradients rather than speed.
Why does Switzerland use a fraction instead of a class number?
Because the system grew out of visual description: the numerator equals the powered axles, the denominator the total axles. Anyone who counts the axles can derive the designation without knowing a list. Only with more modern vehicles did additional number series such as Re 420 or Re 460 come along.
Where can I see a surviving A 3/5?
In museum settings – at railway museums, heritage societies, and announced special excursions. Fixed locations and operating schedules change, so it's worth checking current event notices rather than older lists. There's no regular service in which you'd simply come across the locomotive by chance.
What's the best way to photograph a steam locomotive?
With backlight or side light and cold air. Steam only becomes visible once it condenses – in warm, dry air the plume stays thin. Also plan your position so the smoke doesn't obscure the train, i.e. with the wind blowing across rather than straight into the camera.
Is the A 3/5 comparable to a German class?
Functionally, yes: it filled the same role as the express steam locomotives of other railway administrations, namely heavy passenger trains on main lines. Systematically, no – Germany numbers classes sequentially, while Switzerland describes the vehicle through a letter and an axle ratio. Both systems reach the same goal, just by very different routes.
Log your sighting of the SBB A 3/5
Date, location and vehicle number logged in seconds – and visible to the community.
Related classes
SBB C 5/6 (Elefant)
The C 5/6 'Elefant' was the SBB's heavy freight steam locomotive. This page explains the designation, axle arrangement and today's surviving museum stock.
Electric shunterSBB Ee 3/3
The Ee 3/3 is the classic electric shunting locomotive of the SBB: three powered out of three axles. Here's how to read the designation and identify it reliably.
Electric locoRe 4/4I
The Re 4/4 I was the first series of the Swiss Re 4/4 family: a light four-axle express engine. Today you mostly meet it at private railways and heritage societies.
Who is behind it
Groups, brands, manufacturers and operators – who owns whom and how to recognise them out in the field.
Dampflokomotiv- und Maschinenfabrik AG (DLM)
The Dampflokomotiv- und Maschinenfabrik AG in Winterthur is one of the few businesses worldwide still delivering brand-new steam locomotives after the end of the steam era. Its approach isn't replica building but further development: oil firing, enclosed cabs, modern controls.
Heritage railwayMuseumsbahn Blonay–Chamby
The Blonay–Chamby museum railway links two active metre-gauge networks over the slopes above Lake Geneva across just a few kilometres. The association runs steam and electric traction on its own line – and alongside that maintains one of the most extensive collections of historic narrow-gauge vehicles in Switzerland.
Related guides from the blog
- How Do You Photograph Steam Trains? The Ultimate Guide to Steam Train Photography (Equipment, Settings, Light, Spots)
- Drehscheibe Online & heritage railways explained: finding special-working dates, top heritage railways and photo tips
- Railway Clubs in Germany, Austria & Switzerland: Types, Membership, Costs, Tips
