We’re familiar, and becoming more so, with the electrification of motor vehicles. Tesla, Musk and so on at great length.
There’s also a concept of becoming less electric.
First, a bit of background. Several railway companies working near London use the Class 319 multiple unit, one of those trains which has power under the floor rather than using a separate locomotive. They were built by the then British Rail in the late 1980s. Time moves on and they’re being replaced in most cases by the Class 700, which is controversial in some quarters because it’s made by Herr von Siemens in his factory in Krefeld and the type who voted for Brexit is unhappy with this state of affairs and would have preferred that the contract had been given to a Canadian company whose European HQ is in Germany and would have assembled their units in the UK from mostly imported components. But I digress.
The 319 runs on a diet of electrons, which it gathers from a third rail at 750 V, or from an overhead cable as in the picture which supplies electrons at a more bracing 25,000 V. It uses a transformer, an incomprehensible device ( I find all electric things incomprehensible and suspect witchcraft) to reduce the 25 kV to 750 V to make the motors provide power.
There are, incidentally, a whole lot of reasons why you’d use EVs on your rail network. If you can justify the considerable cost of wiring up, electrics are cheaper to buy and run, more refined, more reliable, more durable and have a better power to weight ratio so better acceleration and reduced journey times. They also move the emissions elsewhere.
The 319 is becoming surplus then and as there’s still plenty of life in the units after less than thirty years of use (remember, EVs last longer) they’re being transferred to less onerous duties. But there’s a problem. Electrification has been delayed or cancelled for some lines so the 319s find themselves with fewer places to go.
Problems beget solutions and it’s been decided that if 319s aren’t going to have electrons supplied, they’re jolly well going to have to supply their own. Job for diesel engines and alternators then. Fortunately several companies make just the thing.
Here’s one, a six cylinder power pack from MTU. It weighs about three tonnes so not an insignificant item to bolt in under the floor.
If that proves insufficient, they do a much more impressive looking and sounding V12, because V12s are always good. Weighs more than four tonnes and is around 21 litres.
So there we have it. How to regress from an EV to one running on diesel (although they’ll retain their mains capability).