If you can take your hub motor apart it means the interfaces between bearings and their shafts and housing are slide fitted. I’ve found even with all steel parts, both 1020 and even 1144 steel, the shaft and housing will deteriorate due to the shock loading of a skate wheel. In the past I’ve use the best high heat retaining fluid available, loctite 620, this stuff is bearing glue and stops “creep” within the housing and on the shaft, which slowly eats away at them as the bearing bangs around, it’s an epoxy, but it can’t handle the loads and heat and deteriorates and you’re back to loose metal on loose metal and the creep continues. Simply put loose keeps getting looser and any machinist can look at these slide fitted motors and tell you it won’t last
If, worse, the motor uses an aluminum bearing housing or shaft, the deformation values of even 7000 series aluminum are way under even the softest steel, and they also have huge thermal expansion. if anything rattles it’ll keep rattling and get worse till the motor is done.
After selling 140 motors and them being out there for a long time I can tell you this from my own experience and feedback. I wouldn’t sell a hub motor anywhere there’s a mandatory guarantee on products because if someone actually rides a decent amount of time on a slide fitted motor it’s likely to be a paperweight before the year is over.
This goes for what I sold, Jacobs, raptor2, Carvon, and everything I’ve ever seen.
Even hardened steel skate axles deteriorate and they aren’t subject to the loading of a hub motor.
Loose always gets looser was obvious but also galvanic corrosion between the shaft and bearings was an interesting surprise. Just like a battery the slightly disimmilar metals touching produces an electrical reaction which also eats away at the metal. When ur playing with an airgap between rotor and stator that’s .4mm things must be precision and slide fittings ain’t it
It likely is subject to less shock loading with the motors out of the wheel and that’s a big plus. I imagine it would do much better but don’t know for sure of course and we will have to see. It’d be nice to hear feedback from people who’ve had hub motors for a long time and get their experience with the mechanical side of things.
I see a lot of promise in direct drive motors, (outside the wheel). This also allows you to use your own choice of wheels with plenty of urethane for dampening and riding comfort, never having to worry about finding replacement urethane for your hubmotor. This would probably help in solving some issues with the slide fit you mentioned.
Ti alloy can be better than steel at avoiding creep with slide fittings but expensive and much harder to machine. Steel is good though and the easier solution is a motor with interference fittings. I think the scorpion shaft is much more so there for weight savings.
I think so too, but it will take so many Amps to drive a direct drive pneumatic tire. I’m interested to see how their V3 motors with pneumatics will perform. I’m have an EVO2 and an extra pair of V3’s on preorder and will be testing out their pnuematics as soon as they are available :).
I’d love to see someone apply a downsized full floating rear axle design. This would have to be a departure from traditional skateboard designs but would allow for 2wd boards with a single more powerful motor. There are already people exploring the use of helical gearing in direct drive satellite motors. This is great because it takes the motor away from direct road vibration like in hub motors. I also had a thought about a hub motor design where the wheels were much larger and there is an air gap between the motor and outer urethane. This would require some kind of suspension that would essentially “float” the motor in the wheel and limiting road vibration. The motor shaft would still be under the same loads but vibration to the motor would at least be eased.
Have you seen the rear drive on the CARVON REV EVO? is a rear single motor dual belt drive with freewheel to allow the rear motors to spin at lower speed when the front hub motors pass the max speed of the belt drive rear.
With a floating axle that axle still experiences the same loads and would need to be an interference fit or the same issues. Two wheels on one axle and one wheel floats and the other is driven would be nice and work but then it’s an inrunner and hard to get the torque. All those gearing methods take up space that could be motor and are all noise making parts that will wear down as well. The easy solution, which is the typical way shock loaded shafts and housings are dealt with… Interference fittings on steel
As just said I guess u could use a single motor to drive two wheels just can’t brake
This? Yep. Low torque helper motor. Def will defeat the low torque issue. But in my opinion, the dual doesn’t suffer from low torque…at 10s the dual hauls ass and fast, can’t even imagine what it would be at 12s. Prob pretty insane. But that motor will help lessen the start up stress and low speed stress.
But at discussion here is abt the longevity of hub motors…and based on @Hummie real world experience, hubs will eventually fail because of the vibrations. But is there an ideal design to combat issue? Is it an issue with the hubs out now and coming out soon?
The solution is the same the world round for heavily shock-loaded shafts and it’s steel shafts and interference fittings. dont know about ti but from what I read it doesn’t do well with interference fittings but maybe could be kept as a slide fitting if it had high deformation number
I didn’t just come to say everything sucks without saying I have something better! I’ll be shrink fitting and winding the new motors, which will match the abec11 centrax wheel size/shape at 83x78. loooong wheel with a long motor over double the size of the old stuff I sold. Interference fitted steel housings AND shaft, as appropriate for heavy shock loads. also nice as there’s no rattling noise. The sound of a motor deteriorating.
and also sit on a 12mm skate axle. Which brings up all these hub motor put a lot more leverage on an axle to say nothing of torque. a typical axle has (2) 7mm bearings and an 8mm gap between so there is …22mm of lever possible. Hub motors on the other hand, all of them, are going way beyond that and still staying with an 8mm axle. I’ve heard of them bending and I’ve heard of them breaking
http://www.liquidnitrogenservices.com.au/shrinkfit.htm
The Acton hub motor that decided to commit suicide did so while I rode it at a slow 3-5 mph pace, do you think that’s what killed it? I never go fast on that thing
@Hummie it just makes sense to over engineer it so that we can’t break it. But cost comes into factor. Is it possible to basically build an indestructible hub at a reasonable price? Is such a motor possible?
I definitely think there is a market for a durable hub that is easily fixable. I think people will extra pay for that.
I would love it if @Mellow could chime in on this thread as they seem to think their German designed and made drive would be superior in performance and durability. They are priced high due to extensive R&D and quality…but be honest, will Mellow’s motor suffer the fate of what @Hummie described eventually? what is the tested/predicted durability of the motors?
carvon has been selling slide fitted motors for a long time. A hardened axle/shaft will take a lot before it wears enough to allow the stator to hit magnets if there’s a big airgap especially, and maybe even slide fitted aluminum housings for the bearings will last a long time too due to the large surface area loads can be distributed through, but if you want things to last years and you don’t want to hear it rattling more and more, and you want the small airgap precision that allows a stronger motor I doubt there’s another way than pressed steel. (Going with ti and slide fittings maybe but that has other obstacles in the making and cost) If it’s pressed steel I believe it could last forever because the shafts and housings don’t suffer in use when they are pressed. If they aren’t then they’re always deteriorating.
