O&K MB 170 N

Updated: August 2026 – A small diesel locomotive with a hood and cab, no class number, but a code like O&K MB 170 N on the frame: vehicles like this can’t be identified from timetables or diagrams. The way in is through two things – the wheel arrangement and the builder’s plate. This page shows you how to read both reliably.

What is the O&K MB 170 N?

The MB 170 N is a diesel shunting locomotive from the Orenstein & Koppel range. For decades, O&K was one of the major German suppliers of industrial, works and light railway vehicles – from small narrow-gauge tractors right up to full-size standard-gauge shunters.

The designation follows a works key: the leading M stands for motor locomotive, and the letters and numbers that follow assign the vehicle to a type and size class. The trailing N is usually read as marking the standard-gauge version, because O&K offered many basic designs in narrow-gauge variants too.

What the key doesn’t give you is reliable output figures or production numbers. Industrial locomotive designs were continually adapted, so two machines carrying the same type designation can turn out quite different. That’s why, for this group of vehicles, the builder’s plate is the real source – just as it is for the O&K MB 200 N or the DIEMA DVL 150. Add to that later rebuilds carried out by independent workshops such as Railtec Eisenbahntechnik in Marl, which refurbishes used shunters and leases them on.

The wheel arrangement notation: the most important tool in the field

When you’re standing in front of an unidentified shunting or light locomotive, the wheel arrangement is the one thing you can work out yourself – no database, no signal, no prior knowledge needed. It appears in almost every type designation and can be checked directly on the vehicle.

Notation	Meaning	Typical for
B	two coupled axles in a rigid frame	light shunters and small locomotives
C	three coupled axles in a rigid frame	medium-weight shunting and works locomotives
D	four coupled axles in a rigid frame	heavy industrial and steelworks locomotives
BB	two groups of two axles in underframes	larger, main-line-capable shunting designs
Bo’Bo’	two bogies with individual axle drive	main-line and general-purpose locomotives

The full system behind the twelve-digit vehicle numbers, in which these features reappear, is explained in the article on reading the UIC number and its check digit. The general approach to identification is covered in the guide to identifying classes.

Where vehicles like this stand in railway operations

Shunting and light locomotives work wherever wagons are moved but no trains are run. That fact alone determines where you’ll find them and how visible they are. It applies to the smaller designs such as the O&K MV 6 a just as much as to the three-axle machines in the same works range. Such works and siding tracks are often looked after by service providers like AnschlussBahnProfis, who organise railway operations behind the works gate.

Setting	Visibility from outside	Note
Private siding of a business	often good, since the track crosses roads	movement only on delivery, irregular
Port and industrial railway	fair to good	often publicly visible sections
Works site behind the fence	poor	private property, no access
Heritage or society railway	good, plannable on event days	vehicles are maintained and lettered there
Storage after withdrawal	variable	locomotives often stand for years

Why the wheel arrangement tells you more than the power output

For main-line locomotives, spotters are usually interested in power output first. For shunting and light locomotives, that’s the wrong place to start – for a very practical reason: the figure is usually not readable on the vehicle at all, and lists often show the as-delivered condition, not today’s.

The wheel arrangement, by contrast, is an observable feature. It hardly ever changes over a vehicle’s working life, it can be read off from almost any half-decent side view, and it narrows down the candidates immediately. Anyone looking at a two-axle machine can rule out every three- and four-axle design from consideration – that’s more sorting power than any estimated output figure will ever give you.

On top of that, the wheel arrangement correlates with the duty profile. Two axles mean a short wheelbase, tight curves, low weight and therefore light works track. Three axles in a rigid frame mean more adhesive weight while the wheelbase is still manageable. Four axles in bogies mean heavy rakes of wagons. A counted number turns into a statement about the operation.

Photographing without getting in the way of operations

Shunting areas are the most dangerous place in the entire railway operation. Vehicles are moved there without signals, without warning and often propelled; the driver frequently cannot even see the leading end of the movement. For spotters, that means there is no situation in which entering the site would be justified.

In practice, this order works well: find a vantage point on public ground, check your sightline, adjust your focal length, then wait. A fence isn’t an obstacle but a compositional tool – with enough focal length and a wide-open aperture, a wire-mesh fence in the foreground all but disappears.

How far you can take this technically, and where the limits lie, is covered in the guide on focal length in railway photography. The legal side – public space, private property, operational railway land – is covered in the guide Are you allowed to photograph trains?.

Common mix-ups and how to rule them out

Verdict

For industrial locomotives like the O&K MB 170 N, there’s no route via timetables or class lists. The wheel arrangement, which you can count yourself, is where you start; the builder’s plate provides the confirmation. Everything in between – colour, lettering, keeper – is a snapshot in time and belongs in your sighting together with the date.