# Tuk-tuk, from old scooter: Two hub motors?



## remy_martian (Feb 4, 2019)

1. They're death traps if you hit the brakes hard rounding a corner. Southern Asia places no value on the lives of its lower-caste occupants or drivers, which is why you see them in use there and nowhere else.


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## Kato659 (Aug 5, 2019)

My father built a trike out of a Volkswagen Beetle 30 years ago. A less refined version of this:









It was fine to drive right up until you tried to turn it and... it would not do it.

Would this be something you would register and take on public roads?


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## el.puerh (9 mo ago)

In those "prognosises" that you both made there, are you assuming that the shaft does not have differential steering? Like here: 




In any case, with two hub motors in the back, the idea was to bypass this problem -- in theory making the turning unproblematic, as they are independent of each other.

Am I missing something? 

Thanks for your feedback.


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## el.puerh (9 mo ago)

Kato659 said:


> Would this be something you would register and take on public roads?


No, not at all. We're talking relatively pedestrian speeds here. Something like max 30 km/h (18-20mph).


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## Kato659 (Aug 5, 2019)

The issue is not the tires scuffing on the corners, it's the turning all being handled by the front wheel, especially if you are hauling cargo. 

3 wheeled ATVs used to be quite popular, but routinely killed people due to combining steering and braking (or acceleration). 4 wheels is a lot more stable.









That being said, if this is going to be a slow mover, that's less of an issue. So where will it be driven? Private land? Just trying to understand the parameters is all. And you of course can build whatever you like, regardless of if I think it's a good idea.


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## adrianpye2 (9 mo ago)

I have an Atul Gemini tuk tuk that I would like to convert to EV, it has 200cc petrol engine with gearbox and differential, so I was thinking 2 motors too.


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## b1oviv19 (9 mo ago)

El. Puerh, You should go ahead with your project. I'm using a QS 138 mid drive on my project. I haven't try others but I shopped alot before buying. I have nothing bad to say about quality, but their aftersales service is non existant. You should buy from a retailer who can provide good assistance. QS also offer many controllers, some are better then others.

The Votol is not fully mappable. 

Where are you located?


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## order99 (Sep 8, 2008)

So...assuming that you're using two independent motors for the wheels-any reason not to create a Tadpole-style trike, with a free-flowing fixed rear wheel, then use the controllers on the two forward wheels in order to steer? A decent amount of cargo could still be carried, and it would be far safer. Admittedly you would then have to take Ackerman angles into account to avoid wheel scrub, but turning and stopping would be far less dangerous...

For an introductory treatise on steering geometry, I recommend the Link below, it will explain why so many on the Forum are worried for you:







Dynamic Stability of Three-Wheeled Vehicles in Automotive-Type Applications


Design considerations for three-wheeled on-road vehicles.



rqriley.hostcentric.com





And a quick design summary of Delta vs Tadpole:



https://rqriley.hostcentric.com/images/fig-3whl.gif



Having said that, the same designer has-on his own Designs page-several Delta trikes that worked well. Note however, that the single-wheel steer designs are both wide-stance and low-stance, while Tuk-tuks are rather the opposite. If your heart is set on a single-steer Delta (and there are some advantages to its mechanical simplicity) I would recommend:

1) Wide, low stance to prevent overspill upon turning/braking and to keep all weight firmly within the 'magic triangle'.
2) More weight towards the rear (same reason).
3) Really good back brakes and a weaker front brake (same reason).

Best of luck!


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