Dual Drive single motor MTB

[Eratrace]

Hi guys,
As I'm new in this forum don't hesitate to correct mi if I do something wrong about the presentation etc.

So now let me explain you my project, I'm working on a mountainboard truck that would have one motor to make the two wheels turn.
To do this im planning to remake the lower section of an MBS Matrix truck with a shaft in the middle.
The motor I want to use is the 6374 with the controller from Alien Power systems, I will also use his 10S 10Ah Lipo Pack with BMS.
So now let me show you where I am on the project:

This would be the prototype looks bulky but doesn't need to be pretty since it is only a prototype.
The bottom part (in green) Is only for the reference as I will use the plastic one from the MBS Matrix.
All the parts except for the axle will be made out of 6061 T6 Aluminum. The axle itself will be in hardened steel with 12mm diameter ( dont yet know what type of steel I still have to talk about it with the one wo will make it for me)

The wheels are 8" Kheo Kicker wheels that where on my mountainboard and i will use the existing holes to mount the plate that connects them to the axle.

In the inside part im planning to use 4 "5201-2RS" bearings and a belt drive system.

I still have to wait a bit to get my cnc mill to start to build so I have some time to think about it.
Now i need some opinion, do you think it would hold with all the vibration and bumps it will take? or should i stop right now and find an other solution?

 

[Squad]

With single 6374 motor is gonna be kinda weak... I wouldn't bother unless You plan to use larger motor, like 80100. For the cost of developing Your own custom parts, next motor and esc can easily be bought to use conventional dual rear drive.

Also have a look here (I don't know german, but photos are cool ) http://www.elektro-skateboard.de/fo...tatt-48/tr-amp-trampa-e-mtb-eigenbau-3999.php This is similiar solution to Yours, might help You a bit.
And use 7075 alu instead of 6061, it's better for machining and tougher.

Anyway, good luck!

 

[Eratrace]

Thanks for that quick answer !
Yeah I also already tought it would be weak but I already have one with esc so it should be good for the test ( if the whole thing blows up with this tiny motor i give up :lol: )
if my system works i planned to buy 2 80100 and make one on each truck ( front and back).
and the point is that i don't want to make the conventional system because it's........... conventional :lol:
This man is using very big belts but his system looks really cool
Still have to figure out if I let the "tiny" pulley on the axle or if I put it on one of the wheels, i think on the axle it will be a bit tiny unless i find A planetary gear reduction that would fit a 80100
And thanks for the alu tip I was thinking about taking 7075 has its also easyier to find but tought it was weaker than 6061 (reading datasheets at this time of the night is quite hard :lol: )

 

[bobfandango]

Nice drawings and design! Leaving aside the power issues (or rather a lack of power), I also notice there doesn't appear to be any differential. So both wheels are forced to turn at the same speed which may only work well in low traction environments where one or both wheels can slip a bit. On grippy surfaces, and especially at extreme turn angles where the outside wheel is turning through a much larger radius, you would end up with some unwelcome effects....

 

[Trampa]

Hi Eratrace,

Putting the motor in the center is not a good idea. It's exactly the spot where you want to have a lot of ground clearance. Try to put your pulley as close to the wheel as possible. The Reduction I can see is not enough. You would end up with a board super fast but not able to take a hill. 14/60 or better 14/70 would be needed for using a 150KV Motor.
The Tr-amp-a from Bruce Lee is using a double reduction. His belts are quite wide, but he needs that strength to cope with the power of his very strong, fast spinning single motor.

Frank from Trampa

Ps.: When you invest a lot of money and effort in such a project, you don't want to mess around with plastic truck parts. My advise would be to choose proper parts right from the beginning. Saves time and money.

 

[Eratrace]

Hi !
Thanks for the reply's
I'm still looking for the best solution so I thanks for the information's.
For bobfandago ( don't really know how tu use the quotes...) : my first idea was to put a differential but it's a lot more complex to design one that would fit and its like with a car you have more fun with a blocked differential (drift car) has with a normal one
@Trampa : Yeah i thought it was to little so need to find a solution (think i found one) and for the plastic parts i had to order on a website selling these and for the not even 10 bucks I tought why not only for test purpose has I dont want to buy the aluminium parts until I know it works, I know they won't last long but has said.... 10$....

So to for the reduction problem I came up with something like this:

A 3:1 Spiro-conical gear reduction and a pulley drive to the axle, would allow to tweak the setting by changing the master pulley but still have enough reduction to run it (3:1 gear + 14/22 pulley).
The motor would also be in an upright position so no problem for the ground clearance anymore.

 

[lowrizzle]

Can you make it? It's very well thought out but very difficult to implement.

 

[Eratrace]

@lowrizzle Yes it should be feasable as the spiro-conical gears would come from a manufacturer ( Michaud-chailly, a french company) for the carter it could be possible with the cnc mill if There is to much trouble with the length of the tool I will maybe need to make an aluminum cast (3D printing in PLA then lost cast). And for the bearings for the axle I still have to find a way to make the slots as it is not possible to maque square holes with a round tool

With the mounting bracket and the rims:

 

[stuntmanmike]

Very nice!
Is a differential being used? Or is it positive traction?
If you check out the Lagrange L1 by Red Rocks board shop they did something very similar with a Surf Rodz precision truck.
I built my dual motor mountain board using two 245kv 63mm out runners & it's really fast. One of these motors would be fine on a street build but for off road, grass etc. you need more . A motor like the Neu Castle 2028 although its an in runner, would work out very well for this.