Looking for a reverse freewheel

[sobriety22]

I have been searching for a freewheel for an 8fun/Befang SWXU front hub motor which spins in the opposite direction to normal (anti-clockwise instead of clockwise) and I was wondering if anyone knows where I can get one? It is so that I can mount two motors on a cart and have them freewheel in the same direction. Cheers!

 

[Deleted member 4366]

Send a message (start a conversation with) directly to Mechaniker.

 

[trex]

dangerous. What'd happen if one motor fails?

 

[RobF]

At the risk of appearing stupid...

If the two wheels are mounted on the same axle - side by side with the cart in between - don't you want them to drive and freewheel in the same direction?

 

[sobriety22]

Send a message (start a conversation with) directly to Mechaniker.

Have already done so, just waiting on him!

 

[Deleted member 4366]

I think he's your only chance. I've never heard of anybody else having them.

 

[sobriety22]

At the risk of appearing stupid...

If the two wheels are mounted on the same axle - side by side with the cart in between - don't you want them to drive and freewheel in the same direction?

Not a silly question at all. Yes I do, but for my particular application I want to have a drive motor in each wheel and because I want the wiring facing inwards that means that one effectively is in the reverse direction of the other. It is fine to reverse the phases for the DC motor but the freewheel action is now in the wrong direction, hence I am looking for an opposite spinning freewheel.

And by cart I actually mean wheelchair, it is for a project of mine. Hence a single axle would not be ideal as the user would like some control over direction by altering the speeds of the wheels.

 

[trex]

what kind of wheelchair that requires TWO WSXUs???
How about this easy to make design:

 

[Deleted member 4366]

Just in case you're interested, Golden Motor have some nice stuff for wheelchair applications. They have a joystick two-motor controller. Conhismotor sell a small direct drive motor that's reversible. I have one of them that I've never used.

http://www.conhismotor.com/ProductsList.asp?iPage=4&id=122

 

[sobriety22]

what kind of wheelchair that requires TWO WSXUs???
How about this easy to make design:

I was thinking something more along these lines (and which can still fit in a house, train, office building, etc.)

 

[trex]

...
Conhismotor sell a small direct drive motor that's reversible. I have one of them that I've never used.

http://www.conhismotor.com/ProductsList.asp?iPage=4&id=122

Good find.

 

[trex]

I was thinking something more along these lines

then SWXU is the wrong choice because of the built in gearbox.
two small direct motors will do this.

 

[sobriety22]

Just in case you're interested, Golden Motor have some nice stuff for wheelchair applications. They have a joystick two-motor controller. Conhismotor sell a small direct drive motor that's reversible. I have one of them that I've never used.

http://www.conhismotor.com/ProductsList.asp?iPage=4&id=122

Thanks for the source.

then SWXU is the wrong choice because of the built in gearbox.
two small direct motors will do this.

The xtender wheelchair shown in the picture actually has a geared drive as well, and I agree a direct drive is optimal but unfortunately weight is a factor. The SWXU is under 2 kgs whereas the DD golden motors are around 4.5 kgs. Also not having resistance to the user when pushing forward when the motor is not running would be a benefit.

 

[RobF]

Not a silly question at all. Yes I do, but for my particular application I want to have a drive motor in each wheel and because I want the wiring facing inwards that means that one effectively is in the reverse direction of the other. It is fine to reverse the phases for the DC motor but the freewheel action is now in the wrong direction, hence I am looking for an opposite spinning freewheel.

And by cart I actually mean wheelchair, it is for a project of mine. Hence a single axle would not be ideal as the user would like some control over direction by altering the speeds of the wheels.

So the wheels are to be mounted on stub axles.

The wiring needs to face inwards on both because routing it across the outside of a wheel would be messy.

Makes sense - assuming my assumptions are right.

My next question would have been steering.

Looks like you've ruled out a differential axle.

Is it possible to alter the speeds of the motor wheels to a fine enough degree to steer?

I had a twist and go hub motor on my Brompton.

The throttle worked fine in that application, but I doubt it would have been gradual enough to steer a two wheel drive vehicle.

 

[sobriety22]

So the wheels are to be mounted on stub axles.

The wiring needs to face inwards on both because routing it across the outside of a wheel would be messy.

Makes sense - assuming my assumptions are right.

My next question would have been steering.

Looks like you've ruled out a differential axle.

Is it possible to alter the speeds of the motor wheels to a fine enough degree to steer?

I had a twist and go hub motor on my Brompton.

The throttle worked fine in that application, but I doubt it would have been gradual enough to steer a two wheel drive vehicle.

Your assumptions are correct. My plan for this wheelchair is for it to be "power-assist" which means that it is not a fully powered wheelchair where the user's only operation is to push a joystick. These kinds of wheelchairs have the user still continuing the action of pushing on the pushrims with the hub motors providing assistance to get up inclines or when the user is tired. Sensors in the pushrim "sense" when the user is pushing and activate the motor, hence steering would just be a matter of slowing down one wheel or pushing more on one wheel.

 

[RobF]

Your assumptions are correct. My plan for this wheelchair is for it to be "power-assist" which means that it is not a fully powered wheelchair where the user's only operation is to push a joystick. These kinds of wheelchairs have the user still continuing the action of pushing on the pushrims with the hub motors providing assistance to get up inclines or when the user is tired. Sensors in the pushrim "sense" when the user is pushing and activate the motor, hence steering would just be a matter of slowing down one wheel or pushing more on one wheel.

Nicely thought out.

Your design relies on two motors, but I think they will be needed anyway.

My mother is an occasional wheelchair user - pushing her up even a modest incline takes some grunt.

I doubt I could manage what one might term a hill.

 

[sobriety22]

Nicely thought out.

Your design relies on two motors, but I think they will be needed anyway.

My mother is an occasional wheelchair user - pushing her up even a modest incline takes some grunt.

I doubt I could manage what one might term a hill.

Thanks! I completely agree with you, I have tried going up a steep incline in a manual wheelchair and it is very hard work. I understand that two motors would be considered overkill but I would be using them at the lower end of their capacity. It is just the cheapest, lightest and most readily available bldc motor that I can think of and which I actually currently have and know the insides of.

 

[Deleted member 4366]

Won't a Bafang SWX motor be too fast? You need one with about 150 rpm or less in a 20"wheel, even lower if the wheel is bigger. I suppose you could reduce the speed a bit by running a 36v one at 24v.

 

[sobriety22]

Won't a Bafang SWX motor be too fast? You need one with about 150 rpm or less in a 20"wheel, even lower if the wheel is bigger. I suppose you could reduce the speed a bit by running a 36v one at 24v.

That's exactly what I'm doing, I already ran a test of a SWXU on a 700cc wheel at 24V and it could have very low rpm. The wheels on the wheelchair will be 24"