Degrees Kelvin is not the approved SI unit. The kelvin is, as is K. So water freezes at 273.15 kelvin or 273.15 K. Not degrees Kelvin, nor Kelvins nor even kelvins (which I wrongly used in an earlier post).
(SI = Somewhat Inconvenient, but there it is!)
The developers of the engine I mentioned see the main transport use to be in commercial vehicles in third world countries, where its multi-fuel capacity would allow more flexibility than a conventional ICE.
Ah. Like a traction engine.
To go with the windmills.
I have also noticed that sound and imagined it to be due to exactly what you have described. A neat way of 'changing gear' electrically instead of mechanically. Robert
Robert
Having listened to Tube trains "changing up" as they accelerate out of the station, and assuming that they can't possibly have mechanical gearboxes, I found this quite interesting!
The Germans and Austrians have tuned some of theirs.
G.Harman
snipped-for-privacy@yahoo.co.uk wrote in news:ghmrfcljv2ht1tatj7naphdvsids8g10l8@
4ax.com:
Great!
It's "just" playing a scale, not the "do-ra-me song". I wonder if that's a side-effect of how they work.
Sounds like we're going back to charcoal burners towed behind the car!
I think they used to run pairs of motors in parallel on starting and switch over to series at higher speeds. That was some time ago and I don't know if they still do.
Me neither, since I have no interest in trains, 'per se', merely in the service they (supposedly) provide.
That description fits with this for older trains.
I think this is what they use now.
Tim
Indeed so - the old DC machines with series resistors and series/ parallel switching. Simple, but inefficient. Somewhere in the loft I have a copy of my calculations for the Class 313 notching curves.
Now slowly passing into history.
Chris
I think that charcoal is one of the things their catalytic burner couldn't handle. However, almost any flammable liquid or gas would work.
Its because vaccines carry a small risk and the twerps can't workout that the risk from the illness is many times more. So they put their child in danger and endanger others that can't have the vaccine for reasons other than stupidity.
Don't worry we are going back to degrees F, foot-pounds, etc. after brexit.
OK, I'm not a physicist.
But I'm enough of one to know that while one kelvin is equivalent to one degree celsius, it isn't a degree. It's just a kelvin.
Andy
Well, I suggest you go and look at your nearest power station.
There's a nice model of one in the Science Museum.
Andy
What? Are you really trying to suggest the temperature of combustion is independent of incoming air temperature?
There are even recuperative furnaces for smelting. I suggest you look up 'recovery boiler design' before showing any more ignorance.
If true, the sequence would have been series for starting, then paralleled for 'cruise speed'. Effectively a two speed "Electric Gearbox" created out of nothing more sophisticated than a cleverly sequenced bunch of contactor switches.
The same trick can be used in hydraulic drive trains where the motors
*are* fed in parallel from the pump to double the starting torque at half speed (they get the full pump pressure at half pump flow rate each) before being 'valved' into series for full/cruise speed (each operating at full pump flow but only half the pump pressure).For passenger cars, I doubt such an 'electric gearbox' technique would be applied (other than as a fixed ratio matching between motor and road wheel speeds in the fashion of a rear wheel differential reduction box as part of the optimisation of the design of the whole power train).
Since an electric motor is, like a steam traction engine, capable of providing high torque from a complete standstill, the necessary voltage controller to control the vehicle's speed can also effectively function as a combined accelerator and automatic gearbox in one when fabricated using modern heavy duty switching converter technology thus neatly saving on the need for an additional box of contactors to switch between series and parallel motor arrangements (or effective poles in a single motor).
A box of contactors in addition to the electronic speed controller would most likely be more at home with rolling stock and heavy duty goods wagons and specialised military vehicles (and possibly off-road 4WD vehicles) otherwise why embellish an already effective switching converter solution to speed control with the additional expense of another box of contactors?
I'm no expert on how the manufacturers *actually* apply these basic laws of physics as they relate to electric (and hydraulic and gross mechanical) power trains[1], just someone who has a comprehensive understanding of the principles the manufacturers are constrained to work with. :-)
[1] When all is said and done, the basic function of a power train is just a specialised application of Archimede's Principle of levers.HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.