Looking for dual shaft motors

[JRP3]

I'm looking for dual shaft motors for an Eboard, similar to this one used by @Stielz I don't know what motor that is, the build thread seems to be gone.



Ideally I'd prefer a sealed inrunner for water proofing. So far I've only found a few outrunners, not many choices.

This is an EZ Run but they don't show a dual shaft on their site

EZRUN series

Discover the power and performance of the HOBBYWING Ezrun series. Experience next-level speed and control with our advanced electronic speed controllers (ESC) and brushless motors. From the Ezrun MAX4 for high-voltage applications to the compact Ezrun 18A Combo for smaller vehicles, our Ezrun...

www.hobbywingdirect.com

I've been told these guys might do a custom dual shaft motor, though this isn't sealed

APS 56115 Inrunner brushless motor 100KV 5000W

APS 56115 Inrunner brushless motor 100KV 5000W

alienpowersystem.com

 

[Chalo]

What are you going to do to let the wheels turn at different rates? Freewheeled driven sprockets?

 

[JRP3]

It will be mostly for off road use so shouldn't be an issue. Doesn't seem to be a problem for people who have done it in the past, even on pavement.

 

[Papa]

I'd mirror Chalo concerns.

My experience decades ago in the Baja 1000, dictated LSD rear and/or front axles, not locked or spools. Lockers and spools (e.g. 'live' rear axle on gocarts), negatively impacts steering off-road), and promotes axle breakage. The links below solve the problem with individual brushed motors (one for each wheel). All you need is one budget controller and 2 or 4, very inexpensive motors:

Gnarboards Electric Skateboards — Boards

Gnarboards Gnarly Electric Skateboards. <br /> Boards: Specs and Pricing

www.gnarboards.com

 

[JRP3]

I've driven many solid axle ATV's without issues. I don't think the HP and torque will be high enough to break things. As for steering, here's a video of that EZ Run on a Stooge board running on pavement:

Moe B Biggs on Instagram: "Introducing the SRB-TripleS Superspine Single. 15kw single motor dual drive #stoogeraceboards"

238 likes, 10 comments - stoogeraceboards on August 7, 2023: "Introducing the SRB-TripleS Superspine Single. 15kw single motor dual drive #stoogeraceboards"

www.instagram.com

 

[JRP3]

Stielz told me in a PM that off road turning was OK but on the pavement it was difficult. Probably because the tires were much larger than on the Stooge raceboard.

 

[JRP3]

I'm toying with an idea using Bellville washers as an overload clutch to allow some slippage and speed differentiation in high traction situations.

 

[scianiac]

The slipper clutch idea is interesting but I can't help but ask why not just use multiple motors like everybody else? With modern ESCs being so small and the much wider availability of smaller motors the weight and efficiency would probably be pretty comparable. Either solution though may be difficult to find innruners in that size that don't have KVs that are way too high. Small diameter inrunners generally have very high KV due to the small rotor size which is probably why most e-boards use outrunners. I do agree though I never liked the idea of using open outrunners due to dirt and water ingress and these new enclosed outrunners are worse in my opinion because they don't cool well. I always figured if I was going to use a outrunner on such a build I would just get an open one and build a vented case for it with an intake filter and fan.

 

[JRP3]

The slipper clutch idea is interesting but I can't help but ask why not just use multiple motors like everybody else?

Traction. On my current 4 motor Atlas when I'm in a low traction high torque situation, like climbing a steep hill, the motor with the least traction starts spinning first and if that doesn't get the board moving the other motors don't kick in unless I give it more throttle, which causes either more wheel spin or a jerky take off.

 

[scianiac]

You may want to look at the traction control feature of VESC controllers then. I think the implementation is still pretty simple but it's designed for that exact purpose to stop a low traction wheel from spinning on a multidrive e-board. Since the controllers knows the RPM of all motors at all times it can just watch for a motor that is spinning up faster than the others and reduce current to that motor. And because the connection is done over the CANBUS I believe it works with as many ESCs as you have connected so 4 wheel traction control is possible. Again you should do some research and see what people say about it who have tried it as I have not. I've been working on a slip based traction control for the VESC based on rpm change as my vehicles (so far) only have 1 motor.

 

[JRP3]

People I've asked don't seem to think much of the VESC traction control function, I guess it needs more work.

 

[scianiac]

Yeah I think how it currently works is rather simplistic so probably not ideal in many circumstances. The two motors with a friction coupling may be an option but another option would be to use one of those single sided shaft innrunners with a two stage reduction and a jackshaft that distributes power to the two wheels. This also solves the issues with the very high KVs of most inrunners, like those hobbywing motors you linked that have a KV 3-5 times that of most eboard outrunners.

 

[JRP3]

How does the jackshaft solve the wheel speed differentiation issue?

 

[scianiac]

It doesn't, just gets you back to your original plan of a solid axle but with a lot more motor options and potentially more power from a given motor.