Talk:Diesel–electric powertrain

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Quantify "recent development"
It would be nice if the "Ships" section quantified what it means by "recent development". There have been diesel-electric/prop ships in the US since at least the 1950s (Puget Sound ferries), and diesel-electric/paddles in the UK since 1934(search for ferry). That doesn't seem all that much more 'recent' than the dates being compared, 1912 and 1920s. (Of course, there's also the problem that ship doesn't mention "diesel-electric" at all.) Seattlenow 08:31, 9 February 2006 (UTC)

Finnish navy also had two coastal cruisers which had diesel electric propulsion. These both ships, Väinämöinen and Ilmarinen, had four Germania diesel engines and two Leonard electric motors. These ships were laid down in 1929, launched in 1931, commissioned in 1932 and 1933 respectively. *Nappula 13:38, 2 March 2006 (UTC)


 * Yes, but how does diesel electric work exactly? — Preceding unsigned comment added by 86.143.234.154 (talk • contribs) 22:26, 22 August 2006 (UTC)

Concerning the advantages of diesel-electric locomotive or DEMU power
"...direct-drive diesel locomotive would require an impractical number of gears to keep the engine within its powerband; coupling the diesel to a generator eliminates this problem." This should explain how. It should be emphasised that power still needs to be transmitted to the generator or alternator via a simple gearbox but this is advantageous because;
 * 1) Mere cables transmit the power to the axle traction motors, not a complex system of rods
 * 2) Sending power to a generator via a low powerband (i.e. diesel) is analogous to sending power to a propeller, in that one gear ratio is enough, unlike sending power to wheels, where several ratios are necessary. This is because the high friction between wheels and contact surface requires a low gear for takeoff to avoid stalling, and higher gears thereafter, since the output shaft moves relative to vehicle speed and would over-rev the engine if just one gear was available.  In a generator or alternator, the force is magnetism, not a high friction surface so a high gear is fine since the magnetism is not great enough to stall the engine.  The result is that the diesel-electric system puts the diesel’s low powerband to best use.

I really want an engineer to check the above! — Preceding unsigned comment added by 89.242.247.137 (talk • contribs) 18:22, 1 August 2007 (UTC)


 * The explanation is essentially correct. However, the article would benefit greatly from a block diagram or pictorial representation of a Diesel-electric powertrain, preferably rendered as a SVG drawing. &mdash;QuicksilverT @ 22:02, 18 February 2011 (UTC)

I worked as a design engineer in one US locomotive factory in the 1970s.
 * Now the technology has evolved, but the older designs illustrate the underlying principles. That is, the diesel engine turned a DC generator, which turned at crankshaft speed, without gearing. That generator's output fed the traction motors, which were DC series-wound motors. At low train speed, the generator operated at low voltage and high current, and the traction motors did also. At higher train speed, the generator operated at higher voltage and lower current. Of course, the product of voltage and current is the generator's electrical power output, which is the engine's output, reduced by any inefficiencies. In short, the generator and the set of motors are the transmission. They are an infinitely variable transmission in that voltage and current can change gradually as the train speeds up. For the motors, high current implies high torque, and that suffices for them to deliver high torque at low speed, the job of any transmission. The generator needs a control system to give it the right voltage-current characteristic as load varies. Overall control requires varying the generator's magnetic field, as well as engine speed.


 * At the factory, engineers referred to textbooks on the design of motors and generators. I do not have good library access at present and I do not recall ever seeing a book on diesel-electric transmission design as such. From inside the factory, the basic idea that voltage and current variations play the role of gear-shifting was pretty obvious. Nowadays the picture is complicated by the use of electronics and AC induction motors. Not only the voltage and current vary, but also the frequency of the AC power to the motors. But the underlying principle is the same: electrical changes take the place of gear-shifting. Somebody with better library access might find these ideas in a book or periodical. Orthobasis (talk) 03:37, 20 October 2011 (UTC)

"Gulping" fuel
Under 'Buses' - Is this really the most formal way to word it? What about "Would be running at it's least efficient point?", or similar? - THD TommyD (talk) 13:08, 4 January 2008 (UTC)

Restored the word "transmission" and the citation
The training msword document was provided to meet a request for a citation for the statement about a mechanical transmission being more efficient than the diesel electric. The document discusses the reasons electric is used instead of mechanical, etc.--68.35.158.218 (talk) 09:05, 18 July 2008 (UTC)

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Redirect
I've moved the page to Diesel-electric transmission, as well as creating a redirect from Diesel-electric powertrain for those who use that term. It's a much better and more correct title - "diesel-electric" is just an adjective.FengRail (talk) 19:59, 8 April 2009 (UTC)

Page move
Reverting my change and following page move proceedures...FengRail (talk) 20:40, 8 April 2009 (UTC)

Hybrid vs Diesel-electric
In the vehicles area listing diesel-hybrid and diesel-electric in the same area could be misleading or confusing. It may be worth only listing diesel-electric vehicles in the area. Benjipc (talk) 02:03, 21 June 2013 (UTC)benjipc


 * I completely agree. Having been a victim of the notorious Wikipedia edit wars, I am not going to change the article. But the automobiles listed do not belong here. They are not "diesel electric" by definition. A diesel-electric transmission uses the diesel engine to power an electric generator, which in turn supplies motive power.


 * The automobiles use a diesel engine to supply motive power and use regenerative braking to recharge a battery that supplies power to an electric motor to supply supplementary motive power. At no time does is the diesel engine involved in the supply of power to the electric generator or to a battery. These cars simply do not qualify as "diesel electric." But, as I've noted, I am going to retrict myself to commenting here, given the nature of the Wikipedia enterprise. Moynihanian (talk) 03:21, 30 December 2013 (UTC)

Cleanup
Added cleanup tag


 * Lists of vehicles need some text to go with them
 * There is an article hybrid vehicle - that some info may be moved to.
 * inline references

I will attempt some of this, but am not volunteering to do all.FengRail (talk) 20:13, 8 April 2009 (UTC)

Under Ships there is a reference to the Queen Mary II: " Queen Mary 2 has a set of diesel engines in the bottom of the ship plus two gas turbines mounted near the main funnel; all are used for generating electrical power, including those used to drive the propellers."

It is not clear from this that it is diesel-electric - it seems to suggest that the diesel engines power the propellers. my thinking was that the propellers should be powered by electric motors powered by electricity from a generator powered by the engines (or turbines in this case) for it to be diesel electric - otherwise it merely has generators attached to its engines. — Preceding unsigned comment added by 78.147.68.211 (talk) 21:53, 21 November 2017 (UTC)

Moving Chevy Volt to Production Ready Cars
Hasn't it been in production for a while now? David1544 (talk) 04:32, 29 March 2012 (UTC)

Full torque at 0 RPM
Why can't an internal combustion engine provide full torque at 0 RPM of the engine-output shaft?

Once the fuel-air mixture is ignited in any cylinder, it should exert a force on the corresponding piston (higher pressure of compressed combusted air, across the area of the piston head) - irrespective of whether the piston yields to this force and moves. The sustenance of this force then depends on the gas pressure inside each chamber. The latter is a function of two things: 1) How long the burnt fuel-air mixture stays hot - thereby maintaining the positive pressure on the piston 2) The timing/sequence of opening and closing of the exhaust and fuel-air intake valves.

Sure - given that 2) is driven by piston rotation (passive valve operation), an ICE will stall at startup if there's a sizeable load resistance; but this is nothing that can't be mitigated by independent active electronically operated valves.

It's a nuance that I thought should find mention on the talk page, if not somewhere in the article. — Preceding unsigned comment added by 220.224.246.97 (talk) 10:07, 7 October 2013 (UTC)
 * The Paxman Hi-Dyne engine was an attempt to produce high torque at low rpm, but not at zero rpm. To start from zero rpm you need an auxiliary power source such as steam, compressed air or electricity. Biscuittin (talk) 19:59, 12 August 2015 (UTC)
 * It is possible to use a Free-piston engine as a gas generator for a gas turbine so I see no reason why it should not be used as a gas generator for a second piston engine. The second piston engine could then start from zero rpm. Biscuittin (talk) 09:19, 13 August 2015 (UTC)

Petrol-electric transmission
There is a growing petrol-electric content in this article so I am thinking of moving it to a separate article. Biscuittin (talk) 20:03, 12 August 2015 (UTC)
 * Created article Petrol-electric transmission. Biscuittin (talk) 20:56, 13 August 2015 (UTC)

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