Motor-in-wheel Crawler?

[heinz357]

....is it just me, or does anyone elses head run off on one when thinking of the possibilities of a motor in wheel setup?

Especially when kit like this is being made...

Radio Control Planes, Helicopters, Cars, Boats, FPV and Quadcopters - Hobbyking*

[BC-Brian]

Those are neat motors but they don't have the torque required for a serious comp rig :\

not that I looked into it or anything

[heinz357]

Still, for something designed for a different purpose to come so close to being suitable for our purpose, I'm sure that a bit of re-designing and research could come up with wheel motors perfect for the task.

...Imagine a zero transmission gear car, with no shafts, low CoG, no pumpkin, huge axle clearance and 180deg of steering. Add to that the ability to turn wheels in opposite directions on the same axle, and it sounds like a great reason for further investigation!

[axial 4x4 crawler]

That would be different, imagine having no torque at all when trying to rock crawl or even drive on a flat surface..

[redsawacs]

I like what you're thinking! MOW rig.....nice!

[Gula]

You wouldn't need a big motor at all to do this. Just put a planetary gear set into each wheel. And attach to motor

[JesterSpec]

Originally Posted by Gula

You wouldn't need a big motor at all to do this. Just put a planetary gear set into each wheel. And attach to motor

Then you'd have no wheel speed.

[BC-Brian]

Originally Posted by JesterSpec

Then you'd have no wheel speed.

Depends on the motor gear combination. 5000 rpm (500kv) and a 30:1 reduction would put you in the right ballpark

[heinz357]

I was thinking that the coil winding pattern, and the sequence with which each coil switches would make a vast difference to the torque output? Also the width of the stator and magnet ring would play a huge part too?


also..

[jason]

Motor in wheel would be awesome and open up a whole new game, not only could you front and rear dig, but skid steering would come into play.

[EeePee]

I could take the time to look for a post JasonInAugusta made a looong time ago about him working on a design like this, but I don't feel like it. Had a drawing for it also.

I guess what I'm saying is, the idea has been there for a long time, but has yet to come around. Maybe because it can't be applied to our little world, or maybe just because no one has been able to pull it off yet, so it'd be sweet to see.

[heinz357]

Exactly! We need shed-loads of torque to get Out of the situation we get Into because we Dont have this level of control. If you have very little in the way of mechanical losses ie, drivegears, CVD's at high angles, UJ's etc, and have the manuverability to avoid bind-up situations, then you dont need as much torque to begin with.

I'm thinking 24 to 36 poles, 3 inch O/D, 30/40Kv, with a simple 2-1 reduction in hub?

[EeePee]

Alright, I have an idea.

I have egressor knuckles for a Losi and they have a flat, aluminum face. Bolt the motor to that via countersunk screws from the inside to the mounting plate of the motor. Make an outer axle bearing knuckle bearing motor wheel and nut sandwich. Then bolt the wheel to the motor. Leave everything else out of the axles.

I think the wheel will be relying on the bearings in the motor to take abuse, and there will be the problem. But maybe the bearings in the knuckle will share the load. Haven't been able to picture it yet.

[heinz357]

Agreed, that specific motor was'nt designed for radial loading, so crawl specific one should have more stator/magnet ring width for greater torque, thus allowing for a wider bearing, or even narrow axial load bearing in combination with an outer thrust bearing, seated on, and tensioned by, a static stub axle on flat faced knuckle?

[EeePee]

How about mini angular contact or even maybe angular roller bearings in the motor.

[heinz357]

Yes, though a full width needle roller would save on cost, weight and space! ;)

[danielk]

Independent Wheel Drive 1/10 Scale RC Car | Project Aelith - YouTube

[wings_of_fire]

Motor in wheel can be done for rc crawlers.

Instead of using complex gearing to match the speed and torque requirement, a micro hydraulic system can give the flexibility and achieve both speed and torque in a small package. A brushless motor is the right power source. All this can easily fit in the small space of a 2.2 crawler wheel.

[jason]

With no shafts to bind you'd be able to turn the wheels as far as you'd like. I could really see this being the next evolution in comp crawling. Holmes needs to get in here and talk motors...

[JohnRobHolmes]

Using a outrunner with 14 poles, the sweet spot for the geardown is 49:1. If you can't get at least 30:1 reduction, the system will not run efficiently or have enough torque compared to what we are used to. I designed a MIW for 2007 nats and scrapped the idea after building one gearbox.



Who is ready to spend $800 in just ESCs and motors? I do know there is a person working on just this idea, because they have to get somebody making the motors ;)