Things that may be overrated

"Cé hé sin" (michael-m-mouse)
09/10/2018 at 15:14 • Filed to: Voith Maxima

Power to weight ratio.

Here we have 5,000 bhp starting 3,200 tonnes (claimed) so less than 2 bhp/tonne. One fixed gear, a torque converter and 12wd is all it needs.

DISCUSSION (6)

eftalanquest > Cé hé sin
09/11/2018 at 12:52

ah yes, the ugly yet glorio us mofo that is the maxima. my employer almost bought the lower powered version if it wasn’t for the unusual engin e. and according to the voith technicians who are attached to our workshop this thing is also a beast to maintain.

here’s how the above looks like when there’s electricity available:

12800 kW (6400 x2), 5000 tons, 16 wheels, wet tracks

Cé hé sin > eftalanquest
09/11/2018 at 18:59

Are those Voith hydraulic transmissions as inefficient as they sound? The latest diesel trains in the UK have ZF six speed conventional automatic gearboxes and our rail operator, which uses Voit h equipped trains extensively, had started an experiment by re equipping one unit with ZF boxes to see by how much they reduce fuel consumption.

bhtooefr > Cé hé sin
09/20/2018 at 08:59

Huh, I figured that a diesel-mechanical locomotive of that scale would be utterly impractical, and if it’s torque converter-based, less efficient than a diesel-electric maybe?

What’s the benefit, really?

Cé hé sin > bhtooefr
09/20/2018 at 11:33

DMUs, at least here, are usually diesel/hydraulic. It’s cheaper, lighter and was at one time more efficient. Modern AC equipment might be better though.

Diesel/hydraulic locos aren't so common nowadays - that one wasn't a commercial success. They were quite a thing in Germany once

bhtooefr > Cé hé sin
09/20/2018 at 14:49

DMUs don’t really exist here.

(Basically, the problem with them is that if they share any rail with heavy service, exactly where you'd want to use them, they have to be built to the full-on crash safety standards of heavy service here. This means that any DMU designs for the US market have to be US-specific, and not many operators want them badly enough to do that. So, instead, we drag passenger cars around with locomotives in those situations.)

Cé hé sin > bhtooefr
09/20/2018 at 15:49

Not a matter that operators here have to worry about as the overwhelming majority of rail traffic is passenger. Interestingly even though their passenger trains have to be built so heavily the safety record on US railways isn’t I believe very impressive by developed world standards.

Also interestingly, the Voith loco I pictured has one gear but two speeds. First speed involves a torque converter driving the gear and then once a reasonable speed has been built up the converter is exchanged (by draining and filling) for a fluid coupling with a lot less slip. DMUs have a three speed where you add a high gear driven by a second fluid coupling.