Comment by Animats | Hacker News Reader

Comment by Animats | Hacker News Reader

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These new locomotives are from Progress Rail, division of Caterpillar, and from Wabtec, which is Westinghouse Air Brake Technologies, 150 years old. They're just Diesel-electric platforms with batteries replacing the Diesel.

"Replacing" may be just that. Few locomotives are built for yard work today. Most US switchers are old road locomotives, often half a century old. Sometimes they have a new power package. Progress Rail started as a locomotive rebuilder, changing out power packages for new ones, usually Caterpillar Diesels. Their electric seems to be a repower job of a classic General Motors Electro-Motive Division GT. Here's a video of their standard new Diesel repower job.[1]

Lithium iron phosphate batteries, at least in the Progress Rail version. The heavier weight of lithium iron phosphate is a feature, not a bug, in a locomotive. Locomotives are built heavy to improve traction.

The end result is not just a yard locomotive. Some of these are in test elsewhere for short-haul lines. Range maybe 300 miles.

Another boring, but useful, technology, from old-line industrial companies. This is what makes the world go.

[1] https://www.youtube.com/watch?v=6Kth3i2PGE0

> Few locomotives are built for yard work today. Most US switchers are old road locomotives, often half a century old.

Here in Germany, we still build new models of railway shunting engines such as the Voith Gravita [1], and we have nearly a thousand (!) of the old V60 in service [2]. Normal open-track models may have superior fuel efficiency at higher speeds, but commonly lack the from-zero traction capability of a specialized shunting engine.

[1]: https://de.wikipedia.org/wiki/Voith_Gravita

[2]: https://de.wikipedia.org/wiki/DB-Baureihe_V_60

Is the "electric" part of the diesel electric a commoditized technology? Is it a single motor or one per axis?

How expensive is a 10MW electric motor? Asking for a friend

Edit: for context - Tesla Semi is just 4x 250kw motors

> Is the "electric" part of the diesel electric a commoditized technology?

Not really. You can't use the electric side of a locomotive drive train anywhere else than in a locomotive, and for fully electric locomotives you can't even use the transformers in any non-railway setting simply because the frequencies used are generally incompatible with usage on the normal power grid. Old electric locos sometimes are used to provide auxiliary power for parked cars [1], though that has fallen out of fashion here.

What is commoditized is the engine side of a diesel locomotive, that's your run-off-the-mill CAT, MTU or whatever industrial diesel engine. As long as it fits into the locomotive body and accepts a hydraulic or electric generator at the output, it can be used. IIRC there even were some experiments with gas turbines on French high-speed locomotives, but these had atrocious fuel economy.

> Is it a single motor or one per axis?

That entirely depends on the engine model, and can be inferred from the wheel arrangement code [2].

[1]: https://de.wikipedia.org/wiki/Trafostation_(Elektrolok)

[2]: https://en.wikipedia.org/wiki/Wheel_arrangement

The usual setup on newer locomotives is that all the wheels are powered by 3-phase motors. Semiconductors the size of bricks control the power, with an AC to DC to variable frequency AC conversion setup. All the wheels are forced into sync by the control system. Multiple locomotives coupled together synch up their wheels. The motors are down near the wheels on such locomotives. No transmissions, differentials, or clutches.

This locked-together wheel drive is a huge win. No more wheel slipping and spinning. Wheel slip has been a huge headache with locomotives back to the steam engine era. The effect is to almost double drawbar pull. Starting heavy trains on upgrades now works much better.[1]

There are many other classic ways to build locomotive drivetrains, but this won out.

UP 4014 "Big Boy", biggest working steam locomotive: 135,375 pounds tractive effort.

General Electric ES44AC, common road locomotive today, over 3700 units built: 183,000 pounds tractive effort.

Dull, boring, from old companies, and very effective.

[1] http://www.republiclocomotive.com/ac-traction-vs-dc-traction...

> You can't use the electric side of a locomotive drive train anywhere else than in a locomotive, and for fully electric locomotives you can't even use the transformers in any non-railway setting simply because the frequencies used are generally incompatible with usage on the normal power grid.

This is a surprise, because it calls to mind this old story:

https://gizmodo.com/that-time-a-canadian-town-derailed-a-die...

Was this simply an unusual locomotive, and therefore compatible with the grid? What's going on?

A locomotive can still output a transformable voltage if you disconnect the traction motors and instead hook them up to something else. A Diesel-Electric engine really is just a generator riding on top of an electric locomotive.

In this case they took MLW M420W locomotives and just straight hooked them right up to the local grid.

That doesn't sound far off from a PTO generator, assuming you've got the right interconnects exposed seems reasonable. From my limited understanding most diesel electrics go Diesel -> AC -> DC -> AC -> Wheels. If your taking power from the first AC part the engine RPM determines frequency(as with a PTO generator). Most diesels used in these applications with similarly buffered powertrains(some tractors/heavy machinery with HSTs/etc) have good governors to keep the engine from running away.

From the article it sounded like it wasn't ideal(there was damage to the gearbox from driving the engines down the road).

(as an aside this is why I think a diesel-electric tractor or pure electric would be pretty nifty thing)

> (as an aside this is why I think a diesel-electric tractor or pure electric would be pretty nifty thing)

Electric motors on tractors are an absolute rarity (usually, the motors need cooling, which is in conflict with the wheel/tracks being rated for driving through water and mud).

The usual is either direct drive or using the hydraulic generator for the power tools and actuators also for the drive train... and you can get electricity generator packs that you can simply plug in into the hydraulics port for a power tool [1].

[1]: https://hk-hydraulik-kontor.de/de/147440-Hydraulik-Generator...

> What is commoditized is the engine side of a diesel locomotive, that's your run-of-the-mill CAT, MTU or whatever industrial diesel engine. As long as it fits into the locomotive body and accepts a hydraulic or electric generator at the output, it can be used. IIRC there even were some experiments with gas turbines on French high-speed locomotives, but these had atrocious fuel economy.

The diesel prime mover is usually an EMD or Wabtec/GE engine in the US - very few mainline locomotives use anything else. They are medium-speed engines and two-stroke (EMD) or four stroke (Wabtec/GE with some EMD Tier-4), built to be reliable, cheap and nearly indestructible. You can swap other engine makes in, but usually with worse reliability and performance.

Outside the US other engine makers are more prevalent, but interestingly US engine designs are the most numerous (except in former Soviet states and China). In the US, newer non-road engines may use Tier-4 MTU or CAT engines for eco friendly power, but they're still the exception and not the rule.

A relatively-new player in the US is Siemens. They're building new passenger locomotives, including electrics for the Northeast Corridor and diesels for elsewhere. The SC-44 Charger and its derivatives [0] use Cummins QSK prime movers, which are high-speed diesels comparable to Euro designs.

[0] https://en.wikipedia.org/wiki/Siemens_Charger

Very true. I’m a fan of Siemen’s push into the market.

> [2]: https://en.wikipedia.org/wiki/Wheel_arrangement

A bit off topic, but I find it mildly amusing that most of the article is taken by the huge table that is entirely about steam loco wheel arrangements, and moreover all of those various arrangements actually have their own article! Rather thorough for a decidedly obsolete technology.

While you can't use the motors 1:1 from what I understand a lot of the development of VFD AC motors happened in the locomotive space[1].

The traction of a DC drive vs AC drive is significantly different(the below article cites at least 2x better for AC) in part due to the fact that a DC motor will "run away" once it breaks the static friction limit where a VFD(holding a fixed frequency) will self-correct as the wheel overspeeds and is slowed down by the other side of the magnetic field. Since most EVs use AC VFD a lot of that same development can be applied in traction applications.

[1] http://www.republiclocomotive.com/ac-traction-vs-dc-traction...

Union Pacific experimented with gas turbine locomotives also.

https://www.up.com/aboutup/special_trains/gas-turbine/index....

The Tesla semi doesn't exist, those are theoretical specs https://www.inverse.com/innovation/tesla-semi-price-specs

One motor per axle except in the Wabtec/GE ES44C4 and ET44C4 where it is four powered axles and two idle axles (Progress Rail has a similar locomotive that didn't make many sales)

For context, Progress Rail is what became of Electro-Motive Division when GM split them off, and Wabtec bought the locomotive division of GE a few years ago.

How is the reliability on those? The diesel-electrics are incredibly reliable.

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