Advice needed for a wheel/motor mount design

Question

Advice needed for a wheel/motor mount design

MrAtkinson (Mechanical)

(OP)

4 Jul 19 07:33

Hi all,

Im new to this forum so please forgive me if this is not the correct place to ask this question.

Im working a 2 wheel scooter type project and im looking at having a small brushless motor within each wheel. The back wheel is perfectly fine, frame/axle through bearing mounted to the wheel base with the motor mounted to the axle to drive the wheel. My questions is what would be your opinions on the best way to do the same at the front wheel but give it the ability to pivot so i can steer?

I only have an 203mm wheel base diameter and 100mm depth from the wheel base to the outside of the wheel to fit the pivot point, 45mm axle and the motor which has a 60mm diameter and is 103mm in length. Id ideally like to keep it all within the wheel base but cant seem to work it out.

Hoping you guys may have a solution i haven't thought of. Quick google sketchup mockup attached (to scale)

Thanks in advance

rothers (Mechanical) · Answer 1 · 2019-07-04 08:42:52

Why do you need to power the front wheel at all ?

MrAtkinson (Mechanical) · Answer 2 · 2019-07-04 09:01:33

Hi Rothers,

Im only using small brushless motors and with the wheels being large + the frame and me one single motor wouldnt be sufficient enough.

Stick. (Mechanical) · Answer 3 · 2019-07-04 09:32:47

Do you have access to rental scooters from one of the new startup companies (bird, lime, etc)? I think at least one of those companies has front wheel drive scooters so you might be able to get inspiration from that design (unless it's patented).

MrAtkinson (Mechanical) · Answer 4 · 2019-07-06 19:54:13

Hi all,

I think i may have cracked it but im not sure on whether the joint will be strong enough to hold the weight. What do you think about the design and do you think i would be strong enough to hold my weight as a pivot point?

This image shows the mechanism without the wheel

RolMec (Mechanical) · Answer 5 · 2019-07-09 08:24:33

some issues
- with that gap shown at pivot point (red circle) the gear shall have much play --> needs to be minimized
- full cover of the gears is a must
- motor being on lower side makes it vulnerable for the next curb, stone or so
- strength is a function of good design, so purchase of external competence in design & analysis are what you might consider at this point

Best of luck in your endeavour!

Roland Heilmann

BUGGAR (Structural) · Answer 6 · 2019-07-10 00:45:08

For your pivots, I'm thinking of bicycle parts. They have little radial load and axial thrust bearings that you could maybe cut down to fit into your design. A bicycle pedal by itself has bearings that resist the load of a huge person pushing in all directions (and then slamming the bike down on top of them).

MrAtkinson (Mechanical) · Answer 7 · 2019-07-15 07:08:24

Hi all,

Thanks for the help with this. I actually found something called a stub axle from a go cart which does basically exactly what i need so have ordered one of those.

I have a follow on question though regarding materials. The wheel is not big enough for me to put a ready made flanged bearing inside as the bearing mounts are huge. Therefore i need to custom make one. I was toying with the idea of using delrin rather than aluminium but not too sure on the strength as ive used delrin before but not in this capacity.

Also, if anyone knows of anywhere that has ready made flanged bearings that dont have a huge mount let me know.

Thanks

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Advice needed for a wheel/motor mount design