Differential on a 2 Wheel Drive Trike?

[Uncle Ron]

Spheroids,

A post by Papa on another thread reminded me of something that I've been curious about and wonder if any one(s) can shed some light?

Who will be the first to try these little cuties? I'd like to see dual cute motor packages run by a single controller 8)

Had I not already sprung for a GM mini, I'd be whipping out the plastic. Still unlaced, the 'mini' sits on my bench in pieces, awaiting a stub shaft for single sided mounting. If all goes as planned, I'll pair this little guy with another and bolt them on the rear of a delta trike. No comment on the 'single' controller for both... yet

With the frame still in the jig and parts strewn all over the floor, it's a safe bet it won't see asphalt 'till spring.

First I'm wondering whether Papa is just ignoring the differential thingy in his build, whether he's using two controllers or a double (dual) controller and just what will be the results in terms of turning at various rates depending on how the trike is set up.

I'm sure I read somewhere here that there are double controllers that can handle two hub motors from a single box, or is my certainty misplaced? If there are such devices, how relatively easy or difficult would it be to initiate an electronic differential controlled by a steering sensor such that power to the inside wheel of a two wheel drive trike would be reduced appropriately on a turn of any radius? This could apply to 2 wheel rear drive on a delta or 2 wheel front drive on a tadpole trike. I don't have the skills or knowledge to answer this question, but it seems like, in my defective mind, that it would be a relatively simple dual controller modification. If it's possible, this would be a far easier and lighter version of 2 wheel trike drive, than moding a trike with a motorcycle trike differential as BLUESTREAK has done?

Papa, if you see this, what is a stub shaft, how does it work, where do you get one, and can it be installed without machining? Quite a question, eh?

 

[Rassy]

There have been a number of discussions concerning differentials and their need on two wheel drive trikes. I have made and used three two wheel drive push trailers and my opinion is there is no reason to bother with any type of differential, mechanical or electrical. Of course both motors should be powered from the same battery pack and use a single throttle. Both the controllers (unless just one controller is used), and motors should also be the same.

I even had a third controller and motor on the front of a delta trike at one time for a total of three motors running off of one throttle. There was never any pulsing or jerking, etc. No problems at all in turns at any speeds. Well, any reasonable speed that is for the trike or bike involved

I realize directly powering the wheels of a trike is different than using a push trailer, but I'm also quite certain that a delta trike would not present any problem. I thought a couple of ES guys (FreddyFlatfoot from Australia and Recompence) were going to try powering the front wheels of their tadpoles, but to my knowledge no one has posted any yet.

 

[Uncle Ron]

There have been a number of discussions concerning differentials and their need on two wheel drive trikes. I have made and used three two wheel drive push trailers and my opinion is there is no reason to bother with any type of differential, mechanical or electrical. Of course both motors should be powered from the same battery pack and use a single throttle. Both the controllers (unless just one controller is used), and motors should also be the same.

Rassy, I sort of suspected that might be the case, but don't have the resources to prove it one way or the other. Thanks for the input.

I even had a third controller and motor on the front of a delta trike at one time for a total of three motors running off of one throttle. There was never any pulsing or jerking, etc. No problems at all in turns at any speeds. Well, any reasonable speed that is for the trike or bike involved

I had imagined that the slower and sharper the turn, the more chance of a non-differentialed 2 wheel drive being a problem in terms of the non powered 3rd wheel not wanting to follow the planned turn? I guess the force must not be that great or the characteristic actions of electric motors on each wheel indendently rather than driven through a single drive train, but might a problem manifest itself in icy situations? Any thoughts on that.

 

[Rassy]

No experience with ice or snow. In a normal year we don't get either here, but we did have 3 inches of snow one night this year.

I don't think the two wheel drive would cause a problem on ice, and of course you wouldn't be going too fast in such conditions. With studs or such, it should work very good. I think it should work more like positraction in that if one wheel slipped a little, the other would continue to be powered. If the front wheel couldn't get any traction, you might have to get off the throttle to make a turn. Might be a lot of fun to play with in an iced over parking lot or pond.

Another thought might be to have individual (steering) brakes on the rear wheels of a delta. I don't think this would be necessary, but it would allow you to slow either motor a bit during turns. I really believe just getting off the throttle a bit would always allow the rear wheels to just follow the front wheel, but as long as you are just talking about sane riding under 20 MPH I wouldn't anticipate any problems.

It'd be nice to see you do this. Then we will really know how it works.

How would you set up the delta trike for pedal only or pedal assist if it had two hub motors? I have only been around delta trikes that had just one rear wheel pedal powered, which would probably be okay even if both wheels had hub motors.

 

[Hillhater]

Rassy, was your set up using brushless motors or brushed with a common controller ?
Brushless i can see as working OK, but i would expect some issues with a common controller on a brushless 2 motor set up.

 

[Rassy]

HH, I must not have been real clear, but I never ran multiple motors from a single controller. I understand the problem with brushless controllers, since the relative positions of the two motors will never stay the same. I think they do make controllers that can power two brushless motors, but they are esentially the same as using two separate controllers.

One of my two motor pushers did use brushless hub motors and a single throttle, but each motor had it's own controller. It worked great.