# does anyone use wheel motors?



## Manntis (May 22, 2008)

as Lexus said, the cost is very high. I looked into some promising ones out of the UK, but they wanted £20,000 per motor. And they didn't even have a mechanical brake, meaning when power was off there was no way to provide braking power for the car. Their demo Mini conversion had to chock all 4 wheels when parked so it wouldn't roll away!


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## coleman (May 27, 2008)

how about from a diy standpoint? I'm thinking something more along the lines of a lower powered (galf cart) motor on each wheel. Mount them inboard connected to the wheel via axle/cv. Use four seperate controllers as well (something like the curtis 1206 or 1204). Use a microcontroller to determine how to best power each motor (ie, run all four motors on acceleration then cut back to two, etc).

Thoughts on that sort of approach?

Chris


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## aeroscott (Jan 5, 2008)

from the metric mechanic.com ,site rear ends loose 20 to 25% of power . that's plus motor and controller loses . so 30% for the rear end .how about a hallow shaft motor with the spider at one end of the motor . a short cv shaft at that end and a longer shaft going through the other end .


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## coleman (May 27, 2008)

The eliica is kind of interesting. I'd say it look s as though they took a fairly standard motor and added a planetary gear housing/wheel mount to the end.

But, again, I'm thinking motor's mounted in the chassis with the same sort of eliica like planetary reduction (or possibly some sort of variable sheave) to an cv/axle/cv drive at each of four wheels. Independently controlled via a "smart" control module, that does some calculation of how and when to apply power to the various motors. Aside from the control module and gear reduction it seems like comparably inexpensive off-the-shelf goodies.

4 x 15hp golf cart motors = < $2000
4 x 400amp motor controllers = <$1000
2 sets paralleled of 4x12v(series) batteries or 2 sets of 8x6Volts or even 3 sets of 4 x 12v

whereas, everything I've seen about a single motor/speed control seems to point to a $2000 advanced dc motor and a $2000 zilla controller and that's just too simple!

Anyhow, does any of this sound reasonable? why/not? or is it just ignorant (cuz I'm an ignoramus when it comes to this stuff)?

It sounds like there are a few folks interested in this general kind of question, with the thread about open source wheel motors and direct drive efficiency. As for the open source thread, I gotta say while I whole-heartedly support the idea of open-sourcing software, taking that to a hardware level (especially something like a wheel motor) is quite, uh, ambitious.

thoughts? comments?


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## electric_soarer (May 12, 2008)

I like your idea. No, I think it's awesome! Smaller motors connected to each wheel. Seems like it could reduce the load on each motor? And you'd potentially have the advantages of all wheel drive. So the control module you're talking about (I envision a low powered pc/pda)would need some means of measuring the individual wheels speed/motor load and alter the throttle input to each of the controllers? It could frequently recalibrate the throttle output to each controller based on the motor load feedback. The only downside is that you now have more moving parts but given that electric motors are relatively reliable that's not a big deal. I'll be thinking about this...


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## major (Apr 4, 2008)

coleman said:


> I'm thinking motor's mounted in the chassis with the same sort of eliica like planetary reduction (or possibly some sort of variable sheave) to an cv/axle/cv drive at each of four wheels.
> <snip>
> thoughts? comments?


Hey coleman,

When you mount the motors in the chassis, then they're not "wheel motors". I'm not a fan of the wheel motor anyway, so this sounds better. But what you'd didn't consider in your parts list is the reducer (you mention planetary) for each motor. This is not a trivial part. Nothing off-the-shelf I know. A show stopper for most.

Regards,

major


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## aeroscott (Jan 5, 2008)

automatics all have little planetary gear sets .i see them at the junk yard all the time . they make some heavy ones for the diesel pickups


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## major (Apr 4, 2008)

aeroscott said:


> automatics all have little planetary gear sets .i see them at the junk yard all the time . they make some heavy ones for the diesel pickups


So you're going to put an automatic tranny on each wheel? Yeah, I know, you're saying to use just a planet set. That will get you about 3 to 1. Chances you'll want more reduction. And how are mounting the planet set? Lubrication? Just not as easy to do as dropping parts into a bucket. But hey, go for it.

Regards,

major


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## Manntis (May 22, 2008)

major said:


> So you're going to put an automatic tranny on each wheel? Yeah, I know, you're saying to use just a planet set. That will get you about 3 to 1. Chances you'll want more reduction. And how are mounting the planet set? Lubrication? Just not as easy to do as dropping parts into a bucket. But hey, go for it.
> 
> Regards,
> 
> major


The HMMVW, sold to civilians as a Hummer H1, has gear sets in each wheel hub as the axle enters the hub at the top, not the center as with virtually every other road vehicle wheel.

Of course, this is among the reasons why HMMVWs are so brutally heavy and have such high maintenance costs...


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## coleman (May 27, 2008)

Granted, nothing is as simple as simple as dropping parts in a bucket.
But, in the grand scheme of things, finding/scrounging/building a gear reducer is trivial. What I'm more interested in is folks response to the general concept. 

What would be the drawbacks to running a 4 motored 48V system?

BTW, how about a small cvt (gear reduction and variable output = low-end grunt and a top end???) at each wheel. or just a simple timing belt affair.

Chris


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## coleman (May 27, 2008)

electric soarer,
Yep, that's the general thought... add a little smarts to the system.


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## jnissen (Apr 1, 2008)

i'll preface this with I have not built an EV yet... So take what I say with a grain of salt!

First 48 volts sounds fairly anemic to me. Will be very high current to make up for lack of voltage.

Second the wheel motor concept sounds great but the devil is in the details. The guyys in the UK who hopped up the mini did it right. They probably invested a couple million on the development of that system. It does antilock, regen braking, anti slip take off, etc... Yes this all can be done but using four off the shelf controllers and then trying to get a microcontroller to manage the interaction sounds like a lot to bite off. I also like to dream but reality has to start someplace. Unless you have tons of time and lots of money I wouldn't go down this path. Sure it would be cool but again I point back to some fundamentals of starting with 48 volts...


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## Manntis (May 22, 2008)

jnissen said:


> i
> Second the wheel motor concept sounds great but the devil is in the details. The guyys in the UK who hopped up the mini did it right.


No, they didn't. There's no allowance for a mechanical braking system at all in the PML Flightlink system. You have to chock the wheels when parked, and if your system loses electrical power you lose all braking ability.


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## SuperChuck_A11 (May 29, 2008)

I bet the MINI is a "push mobile" has anybody seen an article where it is actually driven ??
and in their specs they list enough torque to power a dragster.


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## jnissen (Apr 1, 2008)

Agree PML dropped the ball with the brakes. I had to laugh when I saw the chocks in use as well. You have to admit they did a superb job on the drive and regen brake operation but the zero MPH brake that does not use electricity was not addressed. I do see they now offer an option of incorporating a brake into the design. 

The problem is even with this their system it is still very expensive. I could pay for a lot of gas at that cost.


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