Henry's Poly-V Bike

[acuteaero]

Hi Everyone!

My name's Henry. I've been lurking for a while, enjoying the current and past threads- thought it was finally time to "take the plunge" and start a thread for my old bike project. I first got it running back in April 2010.

(photos from 4/2010)

Errrrr- Screw introductions! We'll get to know each other in time I just received my first ever batch of HK LiPos and hooked 'em up for a test ride. WoooooOoOoooo! 5 lbs of Li instead of 50 lbs of SLA makes for a dynamically different ride! Subtract 90 percent battery weight, add 25 percent power!

Here are the basics: It's an old worn out Diamond Back steel frame bike- I replaced the rear wheel with a disk-brake hubbed one, then added the poly-V belt drive, running a 1:10 single stage non-freewheel reduction from a surplus Kollmorgen motor. At first I was running 2x20AH SLA batteries with the integrated motor controller- when that blew out I ran wires out of the motor and hooked it up to another kollmorgen controller- Just before the REFUEL event earlier this summer I stuck an ebikes.ca controller and third 20AH SLA battery on it to run 36V- I was chatting with Luke at the event, I mentioned that I had had reasonable success with the lead batteries on the bike, as long as the C rate was kept low the lead batteries performed passibly- his response was essentially "No! Lead is no good for anything!"

The wheels have been turning ever since. I can certainly say that there is no reason good enough to put that 50 pounds of lead back on the bike- it feels like a bike again, instead of a creaky lead sled!

In the coming week I'm planning to secure the battery packs better and set up some kind of charging harness, then take the bike on BART for my work commute- about 15 miles roundtrip with long BART ride, fortunately on the Richmond-Fremont line, which has no bike restrictions (that I have been made aware of). There was no way to take it on the train weighing 90 LBS- but with the LiPo I should be able to carry it in and out of the station with no problem.

I've posted about it in the past on my website if you care to look- http://acuteaero.com/category/projects/electric-bike/ . Otherwise I look forward to hearing your feedback on the bike!

I'm looking forward to becoming a part of the community, I'm really impressed by what goes on around here.

 

[spinningmagnets]

I'll be interested to hear how the automotive poly-V belt works out for you. Several other non-hub builds have been happy with toothed belts (Grinhill for a single reduction like you, many others in a two-stage with a belt on the high-RPM first reduction).

I am interested in what will likely be a 2:1 reduction, and only using mid-power levels (500W-1000W), so I may be able to get away with a poly-V without significant slippage. I suspect at high power levels (there are quite a few around here) and with a single reduction from motor to hub, the motor-pulley would experience high slippage.

There is a very wide selection of pulleys in the motor size, what is a good source for a large diameter poly-V pulley? (like the one on your back wheel)

 

[bzhwindtalker]

most dish washer machines uses poly-v belts, and most of the time they have some really nice casted aluminium pulleys that can be put at good use on our bikes. Look out!

 

[Whiplash]

I'll be interested to hear how the automotive poly-V belt works out for you. Several other non-hub builds have been happy with toothed belts (Grinhill for a single reduction like you, many others in a two-stage with a belt on the high-RPM first reduction).

I am interested in what will likely be a 2:1 reduction, and only using mid-power levels (500W-1000W), so I may be able to get away with a poly-V without significant slippage. I suspect at high power levels (there are quite a few around here) and with a single reduction from motor to hub, the motor-pulley would experience high slippage.

There is a very wide selection of pulleys in the motor size, what is a good source for a large diameter poly-V pulley? (like the one on your back wheel)

I am not so sure about that.. In the automotive industry, with a good wrap on the belt, you can run a pretty good amount of boost from a supercharger off these little things, and believe me, that is a LOT more power than our e bikes, even the big boys. It takes an easy 30-50HP or MORE to turn even a low boost setup so I would imagine with good belt wrap, these would be fine even for high power levels... But that remains to be seen...

 

[bzhwindtalker]

poly v on my bike, if your pulley are big enough they wont slip, even with moderately high power (3-4kw)
I used to run my winch with a 1/2 poly-v geardown from a car alternator/power steering mechanism and it took 12kw nicely

 

[recumpence]

most dish washer machines uses poly-v belts, and most of the time they have some really nice casted aluminium pulleys that can be put at good use on our bikes. Look out!

Actually, it is clothes washers that use poly v belts. Maytag Neptune is one of them. The Whirlpool Duet and the Neptune have cast offset pulleys as well.

Matt

 

[acuteaero]

I've also seen poly-v (aka multi-v or micro-v) belts used in washing machines and treadmills as well, and of course automotive serpentine belts- there are three common sizes, J L and M. If I remember correctly most automotive belts are L size. I've also seen some pulleys (out of a Neptune washing machine... with switched reluctance motor, no less!) that seemed to have a non-standard cross section profile that wouldn't have fit the standard belts. Don't know what was up with that.

My belt has been running strong for 350 miles, it's never given me any trouble to speak of, which is good because it's not possible to remove it without allen wrenches- that became a problem after the original kollmorgen controller blew shorting out a motor phase miles away from home... Occasionally the tensioner gets slightly out of alignment and causes the belt to skip a tooth sideways on the rear pulley- adjustment is quick and easy though: grab the tensioner and bend it sideways until the belt runs true again.

I've never had the belt slip, even now with the 44v/40a lipo setup. The front pulley is only 1.2" diameter, but it has nearly 180 degree wrap. While I should think that the high powered airplane motors could slip a belt this size... you can always get a bigger belt- I would think a 6 rib L size like are commonly used as serpentine belts would take the kind of torque the most of the big RC setups are putting out. I had been planning to use a 5M15 HTD belt and #35 chain as a two stage reduction at first, but then decided to try the poly-V because I thought it would be fun and more unique, as well probably more efficient and easier coasting than a 2 stage setup. The bike actually coasts pretty well, even with no freewheel. Unfortunately I probably shouldn't do regen because that reverse torque would work to undo the two part torque-transfer bushing used on the motor shaft.

The way I see it:
Benefits of poly-V drive:
-dead easy to machine pulleys
-self-aligning tendency (not perfect, they can skip ribs, but they can take some amount of misalignment- will cause reduced torque capacity though)
-really cheap and available in many sizes
-long lasting, low maintenance
-pretty quiet
-reasonably efficient
-can wrap around small pulleys
-backside-tensioners OK

Disadvantages include all the usual belt-related problems- can't break them in the middle etc. I'm not sure how a timing belt and a poly-v belt stack up directly in comparison, I wouldn't doubt that the timing belt can handle more torque in a given size belt- but the poly-v has advantages- not the least of which is the ease of machining enormous pulleys for it- like I did here, and the inexpensive belt- this belt was somewhere around $5-$7 if I remember correctly.

 

[acuteaero]

Actually, it is clothes washers that use poly v belts. Maytag Neptune is one of them. The Whirlpool Duet and the Neptune have cast offset pulleys as well.

Matt

Matt is right- I hadn't thought about drive pulleys from front-loading machines- this site http://www.mlittle.com/appliance/neptune/bearings/bearings.php has some good photos of the belt drive on the Neptune washer. Searching ebay returns many results for "pulley" in the washer and dryer parts section: http://home.shop.ebay.com/i.html?_n...kw=&_osacat=20714&_trksid=p3286.c0.m270.l1313 many of which are large diameter, dished drive pulleys, many in cast aluminum. From the photos it's hard to tell if they're all designed for poly-v belts- people tend to take the pictures from altogether the wrong angle to see the edges of the pulley! Some of the clearer pictures seem to show smooth non-grooved surfaces, like they're meant to be used with a flat belt. I don't know. And like I mentioned earlier I'm not sure that all poly-V belts are necessarily conforming to the standard sizes- I noticed the belt in the bearing repair photos is branded Maytag, not Gates or Goodyear- it could be a unique design. Maybe while machining a flange to mount one of these pulleys on in the center one could skim the outside surface and put some nice 40 degree poly-v grooves in it...

Worth a try someday, I suppose. Definitely cheaper and less wasteful than starting from billet like I did- lighter weight too.

 

[recumpence]

Here is something to boil your noodle---- The Whirlpool Cabrio washer uses a HUGE super light weight pancake outrunner motor with hall sensors. The ony bummer is the splined shaft is integral to the inner and outer tub with the stator mounted to the molded tub. A new motor base would need to be manufactured.

I have one of these washers in my garage right now........

Matt

 

[TopCat]

Here is something to boil your noodle---- The Whirlpool Cabrio washer uses a HUGE super light weight pancake outrunner motor with hall sensors. The ony bummer is the splined shaft is integral to the inner and outer tub with the stator mounted to the molded tub. A new motor base would need to be manufactured.

I have one of these washers in my garage right now........

Matt

http://www.youtube.com/watch?v=O1dOcFGP4lQ

[youtube]O1dOcFGP4lQ[/youtube]

Is Matt now thinking of making a windmill to charge his batterys

Regards
Tom

 

[recumpence]

Here is something to boil your noodle---- The Whirlpool Cabrio washer uses a HUGE super light weight pancake outrunner motor with hall sensors. The ony bummer is the splined shaft is integral to the inner and outer tub with the stator mounted to the molded tub. A new motor base would need to be manufactured.

I have one of these washers in my garage right now........

Matt

http://www.youtube.com/watch?v=O1dOcFGP4lQ

[youtube]O1dOcFGP4lQ[/youtube]

Is Matt now thinking of making a windmill to charge his batterys

Regards
Tom

No, a high torque drive motor is a better application for it.

 

[amberwolf]

Many treadmills also use poly-v; some are medium-power, in the 3HP range, maybe a bit more. I dont' know what torque levels they see, but the motor pulley tends to be pretty small, in the 1" to 1.5" range on the ones I have, and 3" to 4" on the walking belt drive roller end.

I used one as the first reduction stage on a treadmill-motor-driven verison of CrazyBike2 for bench tests that worked fine, but it did not end up being road tested as I got those powerchair motors that made the mid-drive so much easier.

I still plan on using one on a bike at some point, just to see how it works out. I just need time....like maybe 72-hour days or something. :lol:

 

[acuteaero]

Busted!

The bike is, that is.

As I mentioned before my plan was to take the bike on my commute, via the BART train- I got all set up to do so on Wednesday. I built up a paralleling setup for the Zippy packs and sewed a bag to hold them and some padding hanging off the top tube on the bike.

View attachment 2

Everything went great in the morning- cut my biking time in half from 40 minutes to 20, on only 3.6AH of capacity- I could certainly go faster next time. No LiPo fires on BART, which while I knew wasn't likely was a pretty scary idea.

Charged up at work using the Hyperion charger and a 24V power supply borrowed from the electrical dept- no problem...

View attachment 1

Then, just before heading home I let a coworker ride it around the parking lot- "it's making a funny noise"- before saying "don't worry about it, that's just the noise it makes..." I hop on and indeed, it's all bad. The belt isn't running right and the motor pulley is scraping like mad. So removed the belt and pedaled it back to the train station. Not fun.



Further investigation reveals something's cut loose in the kollmorgen motor shaft adapter- there's some stiff play in it so that if you move it one way it'll run out, if you move it back it'll run true. Of course last time I put it together I filled it up with bearing locker, so I haven't managed to get it apart yet. Time to get out the torch. I machined the bores of the shaft adapter to fit the shaft very close, so I'm not sure exactly what's happened. I'm curious, but mostly just fed up with the stupid little short D shaft this motor has.

What's next? I'm imagining a complete rebuild- rebuild the motor with new bearings and a nice 1/2 or 5/8 shaft, keyed, 1.5" long... move the motor to just behind the seatpost on a spring-mount, to eliminate the spring idler tensioner- requiring cutting up and rebuilding the seat stay, possibly changing the rear brake around for belt clearance. A new fork with better braking and suspension would also be good.

Is it worth it? Would it work? What do you think?

In the mean time maybe I'll stick this silly 9c motor I have laying around in it (Sacrilegious, I know, in this vaunted section of the forum. But maybe a "frock" ebike is better than no ebike at all?)

 

[Hillhater]

Did you have the motor pulley mounted on the stub shaft extension ??
If so, its not surprising that it didnt hold for long.
Its neatly engineered, but it wont hold up against the side load that the belt puts on it without an outboard support bearing.

 

[bzhwindtalker]

I know this stupidly short shaft too, that's so annoying to build anything on this motor!!

 

[acuteaero]

Did you have the motor pulley mounted on the stub shaft extension ??
If so, its not surprising that it didnt hold for long.
Its neatly engineered, but it wont hold up against the side load that the belt puts on it without an outboard support bearing.

Yes, the pulley was mounted solely on the stub shaft extender/adapter. All the side load was transfered into the motor shaft. Now that I have this experience I will know I can't get away with a fix like this next time

The motor shaft sheared off where it steps down 10mm -> 8mm.

Now I must decide how to procede from here- I like the poly-V drive for the reasons above- robust and cheap, easy to manufacture. I also already have this lovely big pulley. As well, I like the kollmorgen motor for its environmental-sealed, compact package. I don't think it would be too difficult to replace the shaft in the Koll motor.

On the other hand, just a few miles of riding a 9C hub motor bike around has got me convinced that the Koll/Poly-V drive was neither exceptionally powerful, torquey, or efficient. So maybe binning it and starting down a different path is the right way to go- not to say I'm a hub-motor convert- I still just don't like them, and the handling on the front 9C motor bike is atrocious!... but from reading around here there's clearly much more potential in non-hub drive than I realized with the Koll/Poly-V drive- and probably that potential is easier realized using a different architecture.

I don't know if the lackluster torque and efficiency is mostly the fault of the belt type itself, the drive implementation (my particular idler, pulleys), the motor itself, or the reduction ratio (10:1).

 

[spinningmagnets]

The stock ferrous Kollmorgen magnets are weaker than Neos, so no matter how many watts you pump into it, the power per volume/weight of motor is limited. If it was running good and you were happy with the power/amp-consumption, theres nothing wrong with the Koll, but...as long as you need another motor, have you considered some other motor options?

 

[bzhwindtalker]

replacing the shaft is really easy on a koll, you just need to find a suitable remplacement! Its a press fit, a hammer and some care will get it out.