Key takeaways
- The wheel arrangement is the fastest feature there is: counting axles works from a distance and in poor light.
- Letters stand for driven axle groups: B means two, C means three coupled axles.
- An apostrophe marks a bogie, a subscript o marks individual axle drive.
- Type code 98 marks diesel shunting and small locomotives, 92 marks diesel main-line locomotives.
- Location, keeper and livery change constantly – always check the current status.
Contents
Fact file
| Vehicle type | Small narrow-gauge diesel locomotive |
|---|---|
| Manufacturer | Lokomotivbau Karl Marx Babelsberg (LKM) |
| Designation group | Ns – LKM's type series of narrow-gauge shunters, with a digit for the type stage |
| UIC type code | 98 (diesel shunting and small locomotive) |
| Reliable way to identify it | Count the axles, then check the builder's plate |
Identifying features
Is this really the class in front of you?
- Small build with a low body and a very short wheelbase
- Axles in a rigid frame – no bogies, as usual for this size class
- Builder's plate reads LKM, or Lokomotivbau Karl Marx Babelsberg in full
- Type marking of the Ns series with a trailing digit
- Runs on narrow-gauge track, mostly on light, industrial or museum railways
Updated: August 2026 – Counting axles is the fastest identification step in the whole railway hobby: it works from two hundred metres away, against the light, and with no prior knowledge at all. On the LKM Ns 3 and its relatives, it leads straight to the right vehicle group. This page explains how wheel arrangement notation is built and what it reveals about a small locomotive.
Count first, then log it
Wheel arrangement, works number and location in one sighting – so the find stays traceable later.
What is the LKM Ns 3?
The LKM Ns 3 is a small diesel locomotive for narrow-gauge track from the range of Lokomotivbau Karl Marx in Babelsberg. The Ns series groups together the manufacturer’s narrow-gauge small locomotives; the trailing digit marks the type stage.
What matters for identification is which operating category a vehicle like this falls into. The UIC type codes – the first two digits of the twelve-digit vehicle number – draw a clean line here: 98 stands for diesel shunting and small locomotives, 92 for diesel main-line locomotives. A small locomotive, then, isn’t simply a small main-line locomotive, but its own vehicle type with its own approval logic.
Reading wheel arrangements: the shorthand system
The wheel arrangement describes, in a few characters, how many axles a vehicle has, how they’re grouped, and whether they’re driven. Four rules are enough for everyday use.
Letters count driven axles
A is one, B is two, C is three, D is four driven axles in a group. The letters follow the alphabet and the count.
Numbers count carrying axles
A digit stands for unpowered axles. That's rare on diesel shunters, but constant on steam locomotives.
An apostrophe means a bogie
B'B' means two bogies with two axles each. Without the apostrophe, the axles sit rigidly in the main frame – the normal case for small locomotives.
A subscript o means individual drive
Bo means two individually driven axles with no mechanical coupling between them. On mechanically driven small locomotives, you won't find this.
Which type stands before you?
Small locomotive in a rigid frame
Few axles, no bogie, narrow track: that fits the group of narrow-gauge small locomotives, which includes the Ns series too. Check the builder's plate.
Standard-gauge shunter
On standard gauge with few axles in a rigid frame, you're looking at a classic shunting locomotive – wheel arrangement B or C, type code 98.
A larger locomotive
Four or more axles in bogies point to a heavy shunting or main-line locomotive. In the latter case, the vehicle number starts with 92.
How to decode the full twelve-digit number is explained in the article on the UIC number and its check digit; the overall order of identification steps is described in the guide to identifying rolling stock.
Where it fits into railway operation
The wheel arrangement isn’t an end in itself – it reveals the intended use. Few axles in a rigid frame mean a short wheelbase, tight curve radii, low weight – in other words, industrial, light and siding operation.
| Wheel arrangement | Typical vehicle group | Operational meaning |
|---|---|---|
| B | two-axle small and works locomotive | shortest build, tightest radii, small groups of wagons |
| C | three-axle shunting locomotive | more adhesive weight while staying compact |
| D | four-axle rod-driven locomotive | heavy shunting and transfer duty in a rigid frame |
| B’B’ | four-axle bogie locomotive | higher power output, suited to longer runs too |
| Bo’Bo’ | modern locomotive with individual axle drive | electric or diesel-electric power transmission |
Practise wheel arrangements in the field
Log your observations and compare them with other people's sightings – the notation sinks in after just a few outings.
Within the series, it’s worth comparing with the LKM Ns 2 and the LKM Ns 4. What the same notation looks like on standard-gauge vehicles is shown on the page for the MaK 240 B / MaK 240 C, whose type name even carries the axle count directly in the letter.
Only count from a safe position
Count axles from a distance, not next to the track. In shunting and industrial railway areas, vehicles are moved without warning and without a signal, often propelled. Industrial, harbour and light railway sites are private property – track areas are strictly off limits.
From wheel arrangement to vehicle type
The wheel arrangement is the starting point, not the destination. It tells you which group to search in; other features deliver the final match. In practice, this order has proven itself.
First, the axles. Number, layout and the question of bogies. This works from a great distance and already delivers a rough category.
Second, the gauge. It decides whether standard-gauge types come into question at all. With narrow-gauge vehicles, the vast majority of all types drops out immediately.
Third, the drive. Coupling rods, chains, or an empty gap between the wheels narrow the type further and often reveal the era it was built in.
Fourth, the markings. The builder’s plate, type marking and – where present – the twelve-digit vehicle number make the identification certain. Exactly where on a vehicle which numbers are marked, and how to read them off quickly in service, is shown in the guide to finding train numbers and vehicle numbers.
This order has a practical advantage: it moves from features you can recognise at a safe distance towards ones that need proximity or a telephoto lens. That way you never need to approach a track at any step.
For small locomotives, there’s a fifth point that’s easy to underrate: the setting. A vehicle on a light railway museum site is highly likely to belong to a different group than one on a harbour siding. Context is a legitimate clue for poorly documented vehicles – as long as you treat it as a clue and not as proof. A 600-mm small locomotive on the circuit of the Parkeisenbahn Cottbus (Cottbus park railway) stands in a completely different context to the same type behind a works gate.
Common mix-ups
It points to an LKM small locomotive when …
- you count two or three axles in a rigid frame
- the vehicle runs on narrow gauge
- the builder's plate names LKM or Babelsberg
- a type marking from the Ns series is present
Look more closely when …
- frame plates or skirts hide the axles
- the vehicle has been overhauled and freshly marked
- you only have a front view
It's not an Ns 3 when …
- the vehicle has bogies
- it stands on standard gauge
- the vehicle number begins with 92 – then it's a main-line locomotive
In short
One last practical note: the wheel arrangement describes the vehicle, not its condition. A locomotive can be stabled, uncoupled or partly dismantled and still carry the same notation. So always note, alongside the wheel arrangement, the condition and the setting you found the vehicle in. Especially for small locomotives, that’s the information that later separates a proper sighting from a bare type note – and it costs you no extra minute.
Anyone who can read wheel arrangements has a starting point for any unfamiliar locomotive. With the LKM Ns 3, counting leads to the group of small locomotives in a rigid frame, the gauge narrows things further, and the builder’s plate decides. This order works for any industrial vehicle – regardless of how little is publicly known about the specific type.
In short
Count the axles, check for bogies, judge the gauge, read the builder's plate: these four steps reliably place the LKM Ns 3 – with no data sheet needed at all.
Bundle your small-locomotive finds
Wheel arrangement, gauge, works number and date in one place – your overview grows with every sighting.
Summary
- Wheel arrangement notation is an international shorthand system that describes the number, layout and drive of a vehicle's axles in a few characters.
- Small locomotives are dominated by simple forms in a rigid frame, because bogies make no sense on short vehicles.
- The builder's plate, with maker, type and works number, still gives you the final match.
- Light railway and museum sites are private property; access and photography are set by the operator.
Frequently asked questions
What is the LKM Ns 3?
The LKM Ns 3 is a small diesel locomotive for narrow-gauge track, built by Lokomotivbau Karl Marx in Babelsberg. It belongs to the Ns type series, in which the trailing digit marks the type stage. In the numbering system, vehicles like this belong to the group with type code 98.
What does wheel arrangement B mean?
B stands for two driven axles, coupled together in a shared frame. The letter counts the axles in a driven group: A is one, B is two, C is three, D is four. Numbers instead of letters denote unpowered carrying axles.
What does the apostrophe in a wheel arrangement stand for?
The apostrophe marks that the axle group sits in a bogie rather than rigidly in the main frame. B'B' therefore denotes two bogies with two driven axles each, whereas BB denotes four coupled axles in a rigid frame. On very small vehicles, bogies practically never occur.
What does the subscript o mean?
It shows that each axle in the group has its own drive and the axles aren't mechanically coupled to one another. Bo'Bo' therefore describes two bogies with two individually driven axles each – typical of modern locomotives with traction motors, atypical of mechanically driven small locomotives.
Why don't small locomotives have bogies?
Because they're too short for them. Bogies only pay off from a certain vehicle length onward, once a rigid wheelbase would otherwise be too large for tight curve radii. On a small locomotive with two or three axles, a rigid frame does the same job more simply, more lightly and more cheaply.
How do I count axles correctly?
Count the wheelsets, not the wheels – each wheelset consists of two wheels and a shaft. Look at one side of the vehicle and work your way from front to back. Hidden areas under skirts or frame plates can be misleading; a view from slightly ahead helps.
Why do shunting locomotives carry type code 98?
The first two digits of the twelve-digit vehicle number give the vehicle type. 98 stands for diesel shunting and small locomotives, 92 for diesel main-line locomotives. The classification follows the intended use and approval, and so is a quick pointer to the operating category.
Where can you see the Ns 3 today?
Mostly at light railway museums, heritage society railways and in private collections, some still in industrial service. Stock and locations change constantly, because small vehicles are often sold or put into storage. Current sightings are more reliable than older inventory lists.
Log your sighting of the LKM Ns 3
Date, location and vehicle number logged in seconds – and visible to the community.
Related classes
LKM Ns 2
The LKM Ns 2 is a narrow-gauge small diesel locomotive from Babelsberg. Its most fascinating feature is power transmission – and you can actually see it on the vehicle.
ShunterLKM Ns 4
The LKM Ns 4 is a narrow-gauge small diesel locomotive from Babelsberg. If you want to see it moving, plan around running days – not timetables.
ShunterMaK 240 B / MaK 240 C
MaK 240 B and 240 C share the same power class but differ in their running gear. The letter in the type name tells you how many axles are at work.
ShunterKHD DG 1500 CCM
The KHD DG 1500 CCM is a heavy industrial locomotive built in Cologne. The type name and the vehicle number together give you everything you need to place it.
ShunterKrauss-Maffei M 1200 BB
The Krauss-Maffei M 1200 BB is a heavy diesel shunting locomotive on two bogies. The type name reveals power class and wheel arrangement – here's how to read it correctly.
ShunterKrauss-Maffei M 400 C
The Krauss-Maffei M 400 C is a three-axle diesel shunter with a rigid frame. Coupling rods and a jackshaft are the number-one feature to look for.
Who is behind it
Groups, brands, manufacturers and operators – who owns whom and how to recognise them out in the field.
Related guides from the blog
