Multi-Speed Electric kart?

[brandongeiger2]

I was wondering if anyone has ever considered running a gearbox from an electric motor to power a kart or buggy.. I'd assume it is possible like maybe running a mower trans-axle from an electric motor...Just a thought or two. i've never understood why people dont have multi speed gearboxes for electric projects...

 

[scoten7]

I like this idea. But how do you do it?

 

[exenos]

The main advantage of having a electric kart is the even power band. The motor creates equal power and torque across all rpm ranges, so there is no need for a transmission like there is on combustion engines, that unlike electric motors have a uneven power band and create max torque and power at a certain speed.

 

[r97]

Actually, that isn't quite true. With an electric motor power stays about the same throughout the range of rpm, but as the number of rpm increases, torque decreases. The same is true the other way around, as the number of rpm decreases, torque increases. It's actually impossible to keep torque and power constant while varying the rpm.

Electric motors usually can get away with no transmission, saving weight and mechanical losses due to friction. It might also be less expensive to produce just a larger motor than a smaller one and a transmission. That said including a transmission can certainly make better use of the available power in many situations. Applications like ours would benefit significantly from this, providing better acceleration and a higher top speed.

One example of an electric motor paired with a multi-speed transmission can be seen on the Brammo Empulse electric motorcycle.

 

[exenos]

Actually, that isn't quite true. With an electric motor power stays about the same throughout the range of rpm, but as the number of rpm increases, torque decreases. The same is true the other way around, as the number of rpm decreases, torque increases. It's actually impossible to keep torque and power constant while varying the rpm.

Electric motors usually can get away with no transmission, saving weight and mechanical losses due to friction. It might also be less expensive to produce just a larger motor than a smaller one and a transmission. That said including a transmission can certainly make better use of the available power in many situations. Applications like ours would benefit significantly from this, providing better acceleration and a higher top speed.

One example of an electric motor paired with a multi-speed transmission can be seen on the Brammo Empulse electric motorcycle.

Ok, I guess I should have worded it better. By "even power band" i was meaning that there was no torque cure, just that it was a straight linear relation between torque and rpm. I do agree that while it can be done with the size of motors that we are talking about it would probably result in a lot of mechanical loss, unless it is a very good transmission.

 

[r97]

I would like to see someone on here attach an electric motor to a motorcycle transmission, could work very well and still be compact. Maybe I will give it a shot someday, ideally I would try to remove the engine crank and put the motor in between the two main bearings.