Conclusive proof gearboxes are awesome.

[Martin A]

I think the main problem here is a question of semantics or definition of what a gearbox is, which is why this topic seems to be going on and on.

To my mind a gearbox is a device that will enable more than one gear ratio to be selected between the motor and the wheel rim while the vehicle is in motion. i.e the distance travelled per motor revolution is variable. The Tesla does not have this facility, Luke's deathbike (and other single stage reduction bikes) don't and neither do those bikes with gearless hubmotors, but all vehicles must have some sort of gearing even if that is just the distance between the motor shaft and the tyre/road interface.

With an electric road vehicle there are other factors that come into play, namely packaging and unsprung weight, that may result in a necessary compromise of removing the motors from being directly in the wheel, due to the undesireable effects they have on ride and handling.

It is the excess weight of variable gear ratios, devices to enable changing of ratio and all the attendant packaging, in a badly designed electric vehicle drive system that means they are not the best solution (unlike in a diesel or petrol vehicle). The excess weight would be better used in an electric motor designed for the machine and producing more power.

What does make them seemingly awesome is when the excess weight and bad system design is ignored.

Having said that, there may be a case for a fixed length chain from chainwheel to hub that would allow the drive and driven gear to be interchanged when stationary. As this would involve no extra weight, it may be that such a solution may provide a compromise for vehicles with distinct different service duties and a large overall speed range, but you'd have to ask the maths and physics guys about that.

 

[Hillhater]

So I guess the Tesla is a 'geared hub motor' with it's 9.73:1 ratio. Not very direct drive. So the Tesla motor designers
are 'out to lunch' regarding true efficiency. So if you took the Tesla motor and made it larger in diameter to the point
that it was a 1:1 ratio with the motor directly connected to the wheels, LFP would be happy and the motor diameter
would be 9.73 divided by Pi which would result in a motor that is 3 times the diameter and have somewhere in the
neighborhood of 10 times the segments. I guess it's just a matter of cost and size vs. using gears.

Not quite .
There is also the question of weight, and "packaging"
Could you make that motor 3 times the diameter for the same weight as the small motor with the reduction box ?
...and would that bigger motor fit in the space available etc.?

 

[sss]

how is "compensating" lack of torque on EV by using bigger motor any different to using the same method for ICE ?
so if i have x car with 1000cc motor , i need more torque , so i put 2000cc motor inside .
magical solution isn't it ?
whats extra 1000cc to a motor ? its a size increase of approx 3 soda cans to the cylinders .
or you can just strap a huge turbo , or a supercharger . the added weight will be the same as using bigger motor for the EV .

what is often forgotten is with bigger motor , you need bigger EVERYTHING else on the bike or car . you need beefier chassis , drive train components , wheels / chains etc .
of course , you can do whatever you want with your own E-rat bike . you can strap 100kw motor to a bicycle frame and break 1/4 mile records / whatever
or you can push 300A of current with 70c discharge on the poor battery , who needs a gearbox
this is what most of you (me included) are doing with their own creations , pushing motors to 10 times more then rated current , making lightweight 20hp e bikes with a poor bicycle frames etc .
i saw how those poor motors are pushed on Australian ttxgp . some bikes a barely finishing the race with parts blowing all over .
push that much through the motor and the heat destroys the magnet properties , the battery cycle life will go down the drain etc .

this is the EV revolution at its early stage . but once EVs will be more established , imho most of them will use some kind of gearbox , even if its only 2 gears .
bmw i8 uses gearbox , formula e use gearbox . and some day tesla will use gearbox too .

 

[liveforphysics]

how is "compensating" lack of torque on EV by using bigger motor any different to using the same method for ICE ?
so if i have x car with 1000cc motor , i need more torque , so i put 2000cc motor inside .
magical solution isn't it ?
whats extra 1000cc to a motor ? its a size increase of approx 3 soda cans to the cylinders .
or you can just strap a huge turbo , or a supercharger . the added weight will be the same as using bigger motor for the EV .

what is often forgotten is with bigger motor , you need bigger EVERYTHING else on the bike or car . you need beefier chassis , drive train components , wheels / chains etc .
of course , you can do whatever you want with your own E-rat bike . you can strap 100kw motor to a bicycle frame and break 1/4 mile records / whatever
or you can push 300A of current with 70c discharge on the poor battery , who needs a gearbox
this is what most of you (me included) are doing with their own creations , pushing motors to 10 times more then rated current , making lightweight 20hp e bikes with a poor bicycle frames etc .
i saw how those poor motors are pushed on Australian ttxgp . some bikes a barely finishing the race with parts blowing all over .
push that much through the motor and the heat destroys the magnet properties , the battery cycle life will go down the drain etc .

this is the EV revolution at its early stage . but once EVs will be more established , imho most of them will use some kind of gearbox , even if its only 2 gears .
bmw i8 uses gearbox , formula e use gearbox . and some day tesla will use gearbox too .

There is a difference from ICE. When you use a bigger engine it has more windage loss, pumping loss, friction loss, reciprocating losses, thermal losses etc.

When you use an electric motor scaled to match the applications needs directly, you can have both best efficiency and highest performance for the application.

There is no reason every EV can't both be a high performance and a reliable high efficiency watt sipper. It only requires escaping the paradigms of ICE limitation thinking.

 

[nutnspecial]

Variable gearing IS awesome.
Electric motors' 'efficiency' just allows for broader ranges of use without them. For today and tomorrow.

But wake me up if our 'electricity' storage and application someday negates physics.

 

[Hillhater]

how is "compensating" lack of torque on EV by using bigger motor any different to using the same method for ICE ?
so if i have x car with 1000cc motor , i need more torque , so i put 2000cc motor inside .
magical solution isn't it ?
whats extra 1000cc to a motor ? its a size increase of approx 3 soda cans to the cylinders .
or you can just strap a huge turbo , or a supercharger . the added weight will be the same as using bigger motor for the EV .

what is often forgotten is with bigger motor , you need bigger EVERYTHING else on the bike or car . you need beefier chassis , drive train components , wheels / chains etc . .......

........this is the EV revolution at its early stage . but once EVs will be more established , imho most of them will use some kind of gearbox , even if its only 2 gears .
bmw i8 uses gearbox , formula e use gearbox . and some day tesla will use gearbox too .

...you might want to rewind a few pages to get the feel for this thread a little more.
In the case recently discussed (Tesla S) , we were looking to gain 9.7 times as much torque at the motor (but only with the same power ) , in order to theoretically remove the need for a reduction gear, but leaving the SAME torque and power at the wheels. Theoretically it is possible, but the question is is it practical, if not, why not ?
Not quite the same as forcing more power and torque into the existing chassis.

 

[Martin A]

how is "compensating" lack of torque on EV by using bigger motor any different to using the same method for ICE ?......

We don't need to look at the whole post here, just the first line, because with an EV the "compensating" removes the need for a gearbox and clutch or auto transmission. A bigger ICE needs a bigger, stronger, heavier transmission. The whole premise of the 'gearboxes aren't awesome arguement' is that all the excess weight that is the transmission system would be more usefully designed into the power producing motor. Something that cannot be done with an automotive ICE.

 

[John in CR]

Variable gearing IS awesome...

Having sufficient motor to not need variable gearing is more awesome.

 

[nutnspecial]

^ hardly a disagreement or argument to mine. . .
The physical and the energetic are very likely inexorably linked.
We would do best to learn what we don't know before settling on what we think we do.

....
This thread is about proof gearboxes are awesome. The evidence is physics, but proof is just perception and not very useful when used to exclude the unknown, which in this case is as above. Modern E not being awesome or having potential has not been an argument here I'm aware of, but the thread is (at least) about evidence for "gearboxes" awesomeness, which remains obvious to the point of ridiculousness for many. . .

. . .even still with E because it also should be obvious the efficiency label as used in ice and ev (and real world) shows EV can put more power across more rpms, thus only limiting application necessity of variable gearing more than before. BUT if people think that's somehow proof today or tomorrow that physical variable gearing (gearboxes) can and are likewise not improved/improvable, or that it (and therefore physics itself) becomes magically inapplicable to EV in usefulness and even necessity, they might should check their head/argument. Physical and energetic are most likely the same.....

There are still physical contraints on E.
Therefore physical benefits from physical variable gearing will remain.
So like I said -wake me when it's over and physics is negated

 

[John in CR]

There are still physical contraints on E.
Therefore physical benefits from physical variable gearing will remain.
So like I said -wake me when it's over and physics is negated

You must mean the benefit of sharply decreased torque at the wheel with each shift in gear. That's why I don't worry about the launch when a gasser pulls up next to me. Even if they get the jump, when they shift to 2nd I wave bye bye as I blow by.

 

[nutnspecial]

Not really, (what I 'meant') . Although sure it's a valid point and it's included in my own point as a notable factor. I said my piece, so unless there's some sort of argument against. . . thanks for reading it!

 

[Warren]

Turns out the SMESH is used in the Trefecta,

https://www.trefectamobility.com/

and the Storm Wave.

https://www.storm-eindhoven.com/STORM_Wave

 

[macribs]

I never seen or read about SMESH before, thx for bringing that up.
That just seems to be too good not to try it out. I wonder what price and if they do sell to individuals or only in bulk?

Turns out SMESH has been debated before in this thread like a year ago, guess I got old mans memory but in a young, strong & amazingly fit body :lol:

 

[liveforphysics]

That just seems to be too good not to try it out.

SMESH is one of the most appealing of the variable speed options.

A fine solution to a problem that is only a byproduct of picking the wrong initial motor geometry for the applications drive needs. Every added moving part losses and failure modes, this type has fewer than most types of gearboxes, and planetary stages are very strong if done well. Adding the same added mass of this gearing mechanism and using it to grow the radius of the motor and increase pole count and decrease tooth size and the same output torque can be had without added friction and moving parts to add losses until eventually wearing out.

 

[Ypedal]

is that an insult disguised as a compliment ? :lol:

 

[macribs]

LF you are right, I agree. But real life is not always black and white.
There can be various reason why a bigger stronger motor is not applicable for a certain build. It could be real estate, cost, etc.
And for those special occasions it seems SMESH is the better choice of what is available.

If we all could ride ebikes with a light weight 30- 40+kw motors we would never need crouches. But we don't so the debate continues. Guess there is only one way to know for sure, to get one and test it out. From design point of view it would seem such a gearbox would be both light weight and probably not terrible expensive, but then who knows as they don't seem to have competitors.

Purely from a building point of view it would seem like tons of fun using that gearbox. Shift gear at full throttle, pneumatic, electric via buttons.
I am sure it will be a feast to play with.

The results clearly show the differences in acceleration and top speed.
Blue : Motorcycle with SmeshGear® – low gear only
Red : Motorcycle with SmeshGear® – top speed 117 km/h
Green : Motorcycle without SmeshGear® – top speed 80 km/h


It is remarkable that during gear changing (between 33 and 42 km/h) the red line does not fall below the electric motor power output and certainly does not drop to 0 HP. This means that SmeshGear® continues to deliver power to the rear wheel, even during gear changing. Acceleration is also continuous.