Steel-geared hub motor?

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circuit
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Steel-geared hub motor?

Post by circuit » Sep 25, 2013 1:16 pm

Anyone seen those anywhere?

I am planning a 2kW+ build with 12" wheels. Apparently nylon gears will not work. My desire is to find something similar to MAC motor, but with steel helical gears and oil-filled.
* steel means strength and reliability
* helical means silence
* oil means good lubrication and cooling

I have searcher for a few months now, and was able to find only one such motor:
Image

More photos: http://imgur.com/a/9HnRB#0

It is listed in alibaba, seller "Wholewide ..something". Price starts at $60. I got into talking and after three days of chatting they say that they no longer make this motor because of many problems, such as high noise and oil leaks. It was quite difficult to get to meaningful answers while battling through all of the Chinglish.

So I'm stuck. If anyone knows a source of 12" (OD with tire) hub motor with steel helical gears, please let me know.
Or, maybe, it will be easier to take a MAC motor, toss out the gears and machine new ones?
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Re: Steel-geared hub motor?

Post by neptronix » Sep 25, 2013 1:56 pm

You can forget oil cooling most geared motors as they use a type of clutch that will be slippy when oil filled :/

Oil cooled plus metal gears means for eventual metal shavings circulating from the gears. These metal shavings will be in contact with the stator and will collect on the neo magnets if that gear metal is ferrous.. with the BMC and MAC motors, the planetary gear set isn't really separate from the stator, so that could be a source of problems.

The modern plastic/glass impregnated gears are pretty good. If you could deal with welding the clutch to be permanently fixed, you could probably pull off the oil cooling bit.
My first major build: 8T MAC motor on a Trek 4500.
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Re: Steel-geared hub motor?

Post by circuit » Sep 25, 2013 2:18 pm

Yes, I forgot to mention that I do not need clutch, I will weld/replace it.
Good point on ferrous gears and magnets. Maybe brass then?.. Still harder than plastics, not ferrous and should make less noise than steel.

I don't quite get the separate stator part. You mean rotor? Are you saying that sun gear is non-removable, same steel piece with rotor? :shock:
Image

This surely looks like it is welded or something. Anyone have a picture from other side of the rotor drum?

By the way, about motor drag. I have two different 12" wheels/motors and they have very different drag in reverse. Both geared. One is almost unnoticeable and the other is quite loud and drags a lot while bike is pushed backwards. What is the case with BMC/MAC? Will it freewheel freely enough to be compared to, for example, crystalyte x5, when clutch is welded?
Last edited by circuit on Sep 25, 2013 2:42 pm, edited 1 time in total.
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Re: Steel-geared hub motor?

Post by neptronix » Sep 25, 2013 2:40 pm

Maybe what i said could be misunderstood... but basically, there is no seperation between the motor stator/magnet ring and the gear assembly anymore. If you put fluid into the gear assembly, it will get on the stator and magnet ring too.
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Re: Steel-geared hub motor?

Post by teklektik » Sep 25, 2013 6:15 pm

neptronix wrote:You can forget oil cooling most geared motors as they use a type of clutch that will be slippy when oil filled :/
Do you have evidence of failures doing this?

BMC clutches have grease in them from the factory (the clutch - I am not talking about the gears) largely because they share the same cavity with the open bearing between inner and outer clutch components. There are others who have run ATF with no difficulty - for instance - this post. The only difficulty I have experienced greasing the BMC sprag clutch is using a very high content moly lube - using unusually high lubricity lubes (e.g. moly lube - not a characteristic of ATF) is discouraged in references by clutch manufacturers (I found after the fact - sigh...). Some years back mwkeefer was a pioneer in oil-filled and steel geared motors and even had some custom units manufactured for sale, but I'm not sure they had clutches...
The modern plastic/glass impregnated gears are pretty good.
+1. I've run 2kW through BMCs without difficulty. IMHO the improvements in the BMC and MAC gears over the last couple of years have eliminated them as the weak link in the motors - the clutches seem to have taken over that role. Heavy torque seizes the clutches - sometimes they free up - sometimes not. Even when they do, they appear to be permanently damaged (probably due to deformation of the mating sprag surface. Riding with a seized clutch is no problem, it becomes a sort of geared DD motor. The gears don't seem to wear any faster or get any noisier from this bi-directional torque situation since the opposite tooth faces are involved. If you don't want to pedal without power (lots of motor drag), welding up the clutch should be no problem.

FWIW: Lyen sells hardened steel planetary gears for BMC/MAC - ($25) - but these days this looks like a solution in search of a problem...
Last edited by teklektik on Sep 26, 2013 12:00 pm, edited 1 time in total.
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Re: Steel-geared hub motor?

Post by neptronix » Sep 25, 2013 6:54 pm

Nope, i don't know about the lubrication & clutch issue from experience; just that i've heard in many threads that it was a problem, and wasn't willing to sacrifice my own motor for the cause. Sorry if i am spreading misinfo - just passing the word along.

mwkeefer has done some amazing things with geared motors long ago but never showed pictures or anything. I love the guy but have a real hard time believing the claims of 40mph usage on those motors, considering that those tiny stators are gonna be at saturation below 2kW. Though i think he was running them in a 20" wheel and the pole count on those motors is low, like a bafang..
My first major build: 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w on a Turner O2 full suspension.
The wheelie machine: 20" Rear Magic Pie II on a Trek 4300 MTB

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Re: Steel-geared hub motor?

Post by John in CR » Sep 25, 2013 9:50 pm

The bigger problem will be finding any decent quality hubmotor used with a 12" OD wheel.

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Re: Steel-geared hub motor?

Post by el_walto » Sep 25, 2013 10:44 pm

I've hit my mac with 2600Watts and it does OK. Just gets hot really fast.

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Re: Steel-geared hub motor?

Post by neptronix » Sep 25, 2013 11:40 pm

I did 4000W for 5 minutes and made goo out of my white gears.. pretty awesome ;D
There ya go, now you know what a MAC motor does under saturation :lol:

But what you want is reliable continuous power, really. What are these larger geared motors capable of? a spare clutch for a MAC for example ain't too expensive... 'bout time someone found out.
My first major build: 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w on a Turner O2 full suspension.
The wheelie machine: 20" Rear Magic Pie II on a Trek 4300 MTB

"The best time to plant a tree was 20 years ago. The second best time is now."- Chinese Proverb

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Re: Steel-geared hub motor?

Post by circuit » Sep 26, 2013 3:40 am

OK, so it seems that steel-gear motor is for 110mm dropout. No go, then.

Looking now at 8FUN Bafang motors. Can anyone comment on gear noise? How is it comparable to gearless crystalyte x5 or to small geared motors, such as trikke?
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Re: Steel-geared hub motor?

Post by bee » Sep 26, 2013 8:54 pm

I'm also in the market for a heavy duty geared hub motor, we may have to design something ourselves. Would be nice to have something that can handle 4000w or so :)
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Re: Steel-geared hub motor?

Post by circuit » Sep 27, 2013 3:20 am

OK, so I am still searching around.. I see there are basically two types of gears:

Image

I guess larger gears with smaller teeth are quieter? However I can not find any "BMC" motors on alibaba. Does it have a different name?
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Re: Steel-geared hub motor?

Post by crossbreak » Apr 07, 2014 5:25 am

Oil cooled plus metal gears means for eventual metal shavings circulating from the gears. These metal shavings will be in contact with the stator and will collect on the neo magnets if that gear metal is ferrous.
@neptronix: I doubt that shavings get through the bearing into the motor. When disassembling the motor, it wasn't even filled with oil, while the outer part (between motor and hub) was filled with oil. The motor dind't run very long though, I can't exclude that oil could potentially get through the sun gear bearing :? Let's try and see.. I agree that "oil cooling" and steel gearing geared outrunner hubs is somewhat senseless. But here we have an inrunner..


As i'm always keen to see new chinese products, i had to buy one and open + test. Not bad IMO, only really crappy thing is the finish.

Some measurement on this motor

electric:
Inductance: ~1000µH @400Hz
KV: around 57 (i have to measure again with better tool)
Resisance around 200-300mOhm (i have to measure again with better tool)
Lams: 0.5mm
Magnets: 8 (max rpm with acceptable eddy current loss should be around 3750rpm)
Termination: ???
rotor dia: ~63mm
stack thickness ~22mm


Clutch Type: ratcheting, 4 catches
lubrication: oil, seals on both sides

Geometric:
reduction ratio: 7
axle dia: 14mm
spokes flange dia: 137mm, 36 spokes
outer dia
spokes flange distance: 40mm
6-hole disc interface: yes

weight: around 3.2kg

Noise: Less than the bafang BPM. Quite silent, but there is some resonance at ~7kph (26" rim)


any more info needed.. just ask
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Re: Steel-geared hub motor?

Post by circuit » Apr 07, 2014 5:38 am

How loud is it, compared to, say, BPM or similar motor?
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Re: Steel-geared hub motor?

Post by crossbreak » Apr 07, 2014 5:46 am

more silent than all that i had yet, which are cute q100, q75, BF SWXB, SWXH (most silent), BPM, CST. I would say as silent as a SWXH.. but you hear the ratcheting clutch if it freewheels.

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Re: Steel-geared hub motor?

Post by circuit » Apr 07, 2014 5:52 am

That is very good to hear. when I was chatting with one supplier about similar motor (steel helical gears, seen on first post) and he explained me that they no longer sell it due to high noise and leaks.
What do you think would be it's power output compared to BPM or similar? About clutch noise... I'm going to weld it up, as I need regen. How hard is it to spin backwards by hand? Let's say compared to magic pie and crystalyte x5...
What brand/model/link is it? Was going to purchase a couple of BPM, but having second thoughts now.
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Re: Steel-geared hub motor?

Post by crossbreak » Apr 07, 2014 6:07 am

turning backwards isn't that easy, but once it spins i would say similar to a HS3540. Not different from other geared hubs.

I didn't build it into a wheel yet so i can't say anything about the power/torque. you have to wait a few days.. like me

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Re: Steel-geared hub motor?

Post by neptronix » Apr 07, 2014 8:42 am

btw.. this looks much like the geared motor that zelena vozila/greyborg is selling as a 800w motor for $100.
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Re: Steel-geared hub motor?

Post by circuit » Apr 08, 2014 2:42 am

Why not ATF?

BTW where can I buy this motor?
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Re: Steel-geared hub motor?

Post by crossbreak » Apr 08, 2014 2:45 am

jep, that might be the right one. which ATF? I'd like a thin one to lower drag between motor and hub.. maybe i shall change the seals for higher quality ones and check if the axle surface is at that place is properly polished if i'll get sealing issues
where can I buy this motor?
you got mail.. $125 with VAT

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Re: Steel-geared hub motor?

Post by teklektik » Apr 08, 2014 11:11 am

crossbreak wrote:any more info needed.. just ask
Interesting design choices...
Do you have a dyno sheet for this?
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Re: Steel-geared hub motor?

Post by wil » Apr 09, 2014 1:42 am

I'm interested in these too, I'm hoping to build a 2wd drive bike, pushing about 2400 watt, so 1200 per motor, aiming for 70kmh top speed(not for long though~~ ) (https://endless-sphere.com/forums/viewto ... 28#p877728)

Does it look like the stator side could be filled with oil separately from the gear side, so you don't have cross contamination with steel flakes, but still have the benefits oil cooling the motor would have for peak power potential?

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