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This is quite off topic - but its sort of for a bike concept (in my head).

I am playing with a concept of a supreme range aerodynamic electric motorbike. Electric bikes work ok without transmission but the currents go up and efficiency down on low speed starts and accelerating - or top speed has to be compromised. A simple 2 speed transmission with 1:2 and 1:1 ratios would be ideal remedy for the issue.

As this forum has people of various backgrounds I was wondering if someone would know from what kind of machine one could nick such a transmission.

Planetary 2 speed would be ideal - at cruising the transmission would be efficient 1:1 straight through.

thanks.
 

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What about a belt type torque converter?

http://www.northerntool.com/shop/tools/product_21024_21024

Know that one I linked won't take your proposed power, but there are snowmobile clutches that style that handle big hp.

Actually now that I think more;

Had a skidloader with that style drive belt. The shiv on the the drive pulley was hydraulically actuated so you could push the two halves together to increase the diameter. Fairly simply you could have an infinitely adjustable trans between your top and bottom ratios.
 

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if you have the skills, you could always rob the tranny from a hondamatic like a cb750A or a cb400A (or the suzuki version GS450A suuzkimatic) Since these are shared case trannys you would need to build a case for them but there are only 2 gear sets and anybody handy around a machine shop could work it.

Also, lots of kit airplanes use gear reduction drives with multiple speeds to drive the props with engines not designed with big heavy propellers in mind. Not cheap but not super expensive.

Here is a dumb idea - why not a regular motorcycle tranny with a clutch and everything. 1) they are planetary, 2) older seperate 4 speed trannys are cheap, espically off brit bikes like RE, norton, BSA. would give a more motorcycle feel to it. Personally while I think direct drive is fine, the noise of a 14000 rpm electric motor droning on the highway would annoy me.
 

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Motorcycle transmissions are planetary?

Tell me which ones.

An amc gearbox for various norton, matchless and a few others was actually a box designed for 20 horses. Gearing in and out can result in most any ratios you desire.

Seems to me that the max load would likely be a more important consideration for your exercise.

HP considerations using electric motors are a bit deceptive.
 

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quote:Originally posted by Geeto67

actually I have no idea how brit trannys work. The japanese use planetary trannys in most of their bikes. the 1986 ninja 1000r I have has one....I think....
Wow.
No kidding?
I must be living under a rock, I haven't seen them..............
Glad the internet experts are out there to save us from our ignorance.
 

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I would think the torque rating for the tranny would be more important than hp, since torque is an actual measurement and horsepower is a made up number that comes out of crashing numbers together.

even though it is not planetary I still think a brit 4 or 5 speed isn't a bad idea. it is designed for the torque and hp ratings similar to a small electric motor. having 4 speeds may be a bit much but at least you get up to speed a lot faster.
 

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Again, torque and HP are different ways of expressing the same thing. HP at a given RPM is always the same torque, and vice-versa.
 

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Electric motors can be operated via two controllable inputs

voltage and amps

Heck, they can be coupled to a gear box or final drive sans a clutch and function very well because of this, unlike an internal combustion engine
 

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I didn't even think about it but yeah, if there is no current going through the motor it freewheels so you really wouldn't need a clutch. However, how do you get that to work with regenerative braking where the motor goes from being a motor to an alternator as you slow down?
 

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quote:Originally posted by mlinder

Again, torque and HP are different ways of expressing the same thing. HP at a given RPM is always the same torque, and vice-versa.
Right, but gas v. electric they devolop their power much differently.

On equipment that can be ran either/or the easy rule of thumb is double the electric hp for a gas engine. i.e. 10hp electric = 20hp gas
 

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quote:Originally posted by Geeto67

I didn't even think about it but yeah, if there is no current going through the motor it freewheels so you really wouldn't need a clutch. However, how do you get that to work with regenerative braking where the motor goes from being a motor to an alternator as you slow down?
It's done via the controller.

I'd agree that at least 2:1 would be a good baseline although reasonably irrelevant.
 

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quote:Originally posted by HackAsaw

quote:Originally posted by Geeto67

I didn't even think about it but yeah, if there is no current going through the motor it freewheels so you really wouldn't need a clutch. However, how do you get that to work with regenerative braking where the motor goes from being a motor to an alternator as you slow down?
It's done via the controller and most common ev motors will actually generate dc when motored.

Im not very experienced with the latest ac high zoot stuff and havent studied it due to apathy.

I'd agree that at least 2:1 would be a good baseline although reasonably irrelevant.
 

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quote:Originally posted by Ratty-550

quote:Originally posted by mlinder

Again, torque and HP are different ways of expressing the same thing. HP at a given RPM is always the same torque, and vice-versa.
Right, but gas v. electric they devolop their power much differently.

On equipment that can be ran either/or the easy rule of thumb is double the electric hp for a gas engine. i.e. 10hp electric = 20hp gas
:(

That's like saying 10 gallons of water is the same as 20 gallons of paint thinner...

Horsepower is horsepower. Please don't think I'm trying to come off as a dick, I'm not. But measurements are measurements. They don't change depending on what you are measuring. A cubic foot is a cubic foot, regardless of what's occupying that space.

The issue that's run into with electric motors is that the torque curve over RPM is flat and available instantly, which is completely different than internal combustion engines, which can be hard on attached machinery.
 

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I think you hit on it Mark....

It's perception. That10hp electric hits RIGHT NOW with all the torque it's got to offer.
The gas engine has to spool up, so a transmission that's going to be run with an electric motor must be stronger than what a gas engine needs. At 0rpm and full mechanical load that electric motor can wreak some havok.
 

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Wow..... now the next thing for practical applications that can be thorny

would be bearing speeds

As in very few motorcycle or even cvts are designed to handle 15k input shaft speeds regardless of the load
 

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Oh, good point. Hadn't even considered that far ahead yet.
 

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It can get even stickier when doing gear reduction gear boxes and on the over-run if the motor's bearings are already marginally engineered, if durability is a concern.

EV applications are generally a bit easier when using a motor which operates with shaft speeds more similar to a diesel engine than a F1 engine even though there are ways to make most anything work.
 
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