Britain has largely forgotten that locomotives can usefully pull passenger trains. With most of the TOCs almost exclusively using DMUs and EMUs in various configurations, the humble locomotive has been primarily consigned to freight and work trains.

But that is not true of other countries around the world. Even developed railways such as DB in Germany still use locomotives for passenger services, gaining operational flexibility as they do so. If a breakdown occurs, or major maintenance is required, they just swap the loco – they don’t have the whole train out of service.

So it is not really surprising that a modern range of locomotives can sell in large numbers. Bombardier alone has delivered over 1,500 examples of its TRAXX family for freight and passenger services in the last 12 years.

With the various standards of electrification in different countries, there are naturally different models. The TRAXX AC covers 15kV and 25kV AC systems. The DC model is for 1.5kV and 3kV DC systems, and there is even a Multi System model that will handle all four supplies. And then, of course, there is the diesel-powered DE.

Now, a new model has made an appearance, the TRAXX DE ME – ME stands for multi-engine, as the new locomotive has not one diesel engine, but four.

Four? Why four?

Just because the loco has four engines, it doesn’t have to use all of them all of the time. It does when it needs full power, but when power requirements are low, such as when running light or with an empty train, or downhill, the excess engines can be simply shut down, saving fuel and running time (and hence maintenance costs). Compared to a single engine system, fuel consumption can be reduced by up to ten percent. Over 20 years, this may generate savings of around one million Euros in a single locomotive.

Every one of the four engines in the new locomotive is independent – it has its own generator, its own coolers, and its own fuel supply. So when one or more engines are shut down, the rest keep running.

It’s even cleverer than that. When more power is needed, and an extra engine has to be started, the computer automatically selects the engine with the lowest running time, so as to keep the usage on all engines as even as possible. A neat touch that keeps maintenance costs down.

Talking of costs, small engines are cheaper than big ones. The ones in the new DE ME are C18s made by Caterpillar, which makes them in large volume on a production line.

By the way, large and small are still relative terms. The single-engine TRAXX DE locomotive uses an MTU 16V 4000 R41L engine – 64 litres capacity and with an output of around 2,200kW (2,950bhp). The “small” engines are 18 litres each (72 litres in total) with a total rated power of 2,252 kW. By way of comparison, a standard car diesel engine is doing well to get up to 100kW.

Another advantage of going for a high-volume engine is that they are produced to the latest emissions specifications. The Caterpillar C18s are certified to the Stage IIIB EU emission standard. The use of a sealed particle filter system makes the TRAXX DE ME one of the cleanest diesel locomotives worldwide.

And of course, volume-produced industrial engines are mature designs, reliable and quick to repair. The maintenance costs are approximately two thirds less than those of a comparable modern single-engine locomotive.

And using smaller engines, of which one or more may not be running at any one time, makes the whole thing quieter and reduces emissions.

Nothing is new

Having several engines in one locomotive is not actually new. Bombardier has done it before, in various forms.
Between 1998 and 2003, 36 twin-engined locomotives were delivered to the Greek national railway OSE which still uses them for passenger transportation.

Bombardier also produces a TRAXX AC Last-Mile. This is a conventional AC-powered electric locomotive, but which has an onboard diesel engine as well. While it normally runs underneath overhead lines, the additional engine allows it to bridge short distances, for example in cargo terminals or in harbours. The locomotive actually has three power sources, as it also recovers braking energy to its batteries and then reuses it.

And in North America, the TRAXX ALP- 45DP dual power locomotives operate on partly electrified routes in urban areas, where emissions are most annoying. Therefore, its two diesel engines are only started where there is no overhead line, saving both diesel fuel and emissions wherever possible.

And it’s a TRAXX

As well as having the new engine configuration, the new locomotive benefits from being part of the TRAXX family. Ulrich Jochem, the president of Bombardier’s locomotive business unit, explained why.

“It can be configured for operation in different countries with the same modules as our TRAXX electric locomotives. As a platform product, the TRAXX DE ME offers operators the benefits of long-term spare parts availability. Further, it offers savings due to commonality within a mixed fleet of TRAXX locomotives and a high residual value beyond the service life of the locomotive. Our TRAXX customers also benefit from the fact that we have a successful service network which extends throughout Europe.”

Future possibilities

Mr Jochem described how he saw this and other concepts developing in the future. “Modern drive technology will permit us to offer a completely different combination of various sources for the output and storage of energy,” he commented. “For example, we could imagine replacing the fourth engine of the TRAXX Diesel Multi-Engine with a battery storing re-utilised braking energy.

“Another important project on the way towards the locomotive of the future is the Eco Rail Innovation (ERI) Platform, which is intended to help achieve the zero emission target of DB by 2050. The largest project within the ERI initiative is the Energy Tender Project which addresses electrification without overhead contact lines. We are extremely proud that this project will, from now on, be carried out with our support. One of our DB class 146.2 locomotives (a TRAXX P160 AC2) will serve as a test locomotive.”

That sounds like another project which the rail engineer will be covering in the coming months.