Slipper clutch

[mwkeefer]

Matt,

This may seem silly (probably is) but what would you think of a 4:1 HTD type primary (which can handle a darn fair amount of torque and high RPM) and then driving a V to the rear?

At first thought (I didn't go much further with it) it seems the weight would be similiar if not better than normal chain drive.

That puts stage 2 in the (assuming 6500 rpm @ shaft) 1650 RPM stage but with 4x the torque, I would assume the RPM is fine for V belts but...

1.) Would slippage transfer to the second stage so the v belt slipped or would the HTD still skip teeth in overload?
2.) How would the efficiency of a V with the fastest travel being approx 1650 RPM?

I know you have alot of Major appliance experience, don't commercial washing machines employ these slipper clutches?

On a related but different note - what ever happened to your leather shoed slipper clutch from that first build?

Can you quote a price for a replacement large HTD pulley for the V3 drives with the slipper clutch built in (assuming no trade in)? Having just ordered an HV ICE 160 (took forever to find one) and an HV ICE 80 (for lower powered builds and just a backup) the idea of adding a slipper clutch so I can WOT from dead stop is very appealing to me so the HV sees mostly if not all WOT

-Mike

 

[recumpence]

Hey Mike,

The issue of V-belt slipping is related to many factors;

#1 Belt width.

#2 Belt tension.

#3 Pulley size.

#4 Amount of torque pulled through it.

Yes a lower RPM will increase efficiency of the belt (typically), but, then you will need a wider belt which requires more torque to overcome drag and you are back where you started.

V-belts are not terrible in efficiency. But, they are not as efficient as a toothed belt in most applications. I am not saying anyone who uses a V-belt is foolish. On the contrary, there are a number of applications they serve well. But, for maximum efficiency, I am somewhat against them. Of course, some of that may be merely related to the "Cool" factor of toothed belts. Honestly, though, I looked into using them and found more drawbacks than benefits for our particular application.

I am not sure of the cost of a clutch and pulley together. However, I would hazard a guess at about $150 or so (that freakin pulley costs a fortune to make).

Washers do use a slipper clutch for the very same reasons I do. They are not an easy adaptation, though. It would cost more than using the clutch I am using and they are too big.

My recumbent clutch (the aluminum and leather clutch) is holding up fine. However, it is not a constant slip clutch like this one on my trike. The recumbent clutch is a intermittant use item for sure. This trike clutch can be slipped almost indefinately without objecting. Heck, I pulled my two boys (400 pounds of me, bike, trailer and boys) up some steep hills today. I nailed it at the bottom of the hills and let the clutch slip all the way up. No problems. ------- Everything has become a R&D opportunity these days.

Matt

 

[mwkeefer]

I'm surprised you haven't figured a way to sensor the slipper revs and count the times and amount your slipping - an eagle tree and optical? All jokes aside, any thoughts on embedding maybe a magnet for pickup by a hall sensor to detect slippage?

I tell ya, after all the bling bits you turn up - I think maybe I didn't spend enough time taking apart large home appliances

The V belt just seemed like a possible stop gap or diy solution, heavy and steel or not - embedding in the first pully (lowest torque point) is truly an elegant solution to both the belt or chain breakage and requirement to use partial throttle on RC controllers.

How warm did the large pulley or the steel inset get after your hill charge with the kids in tow? I'm doubting it would really be of an issue in a well engineered (ie: properly volted and geared reasonably) system - there the slippage would be only at the absolute peaks right?

Is the slip point adjustable? or atleast perhaps a "Lock Out" on the slipper clutch? (thinking of days long past when I would use Line Locks to stage on Island Ave in Philly)?

-Mike

 

[olaf-lampe]

Hi mwkeefer,
I'm afraid putting the v-belt on the second stage could end up bad.
In general you need a higher torque to 'brake the belt loose' and a lower torque when it is already slipping. This will cause an oscillating current in the controller. ( This is audible too in cold weather, when the belt slips in your ICE-car)
I believe, putting the belt in second stage could multiply this problem ( adding the slack of the HTD belt ) , producing much higher current ripples

The more I think about it, the more traps I find in my idea...
-Olaf

 

[Jeremy Harris]

The issue is efficiency. Though a V-belt can be relatively efficient, at high RPM on a small motor pulley, the losses build up. That is the reason I never went with a V-belt. It will work, though.

Matt

We're talking polyvee belts here, Matt, not vee belts. They are more efficient than vee belts by a fair margin. This is one of the reasons polyvee belts are used so much as aux drives on cars, for things like alternator, water pump, power steering etc. Polyvee belts have pretty much taken over from vee belts for this application, as far as I can see. I didn't notice any increase in belt/pulley heating when I switched from an HTD to a polyvee on the prop reduction drive and that was running at around 30hp, where even small belt losses would have meant a lot of heat.

Jeremy

 

[recumpence]

The issue is efficiency. Though a V-belt can be relatively efficient, at high RPM on a small motor pulley, the losses build up. That is the reason I never went with a V-belt. It will work, though.

Matt

We're talking polyvee belts here, Matt, not vee belts. They are more efficient than vee belts by a fair margin. This is one of the reasons polyvee belts are used so much as aux drives on cars, for things like alternator, water pump, power steering etc. Polyvee belts have pretty much taken over from vee belts for this application, as far as I can see. I didn't notice any increase in belt/pulley heating when I switched from an HTD to a polyvee on the prop reduction drive and that was running at around 30hp, where even small belt losses would have meant a lot of heat.

Jeremy

Are you talking serpentine, multi-rib belts? Ahh, yes, are talking right past each other.

Thanks for clearing that up, Jeremy.

Yup, appliances use them with great success.

Oh, ribbed belts do not like slipping much. They burn up easily. They are a great belt for many applications, though.

Matt

 

[Whiplash]

I really like the idea of a slipper clutch to control power spikes, it would certainly seem like this could be the cure for the person who gets the occasional burnt controller and also keep people from ending up on their butt like one or two videos posted on here! LOL!

 

[Jeremy Harris]

Are you talking serpentine, multi-rib belts? Ahh, yes, are talking right past each other.

Thanks for clearing that up, Jeremy.

Yup, appliances use them with great success.

Oh, ribbed belts do not like slipping much. They burn up easily. They are a great belt for many applications, though.

Matt

The polyvee belts I used were these: http://www.transdev.co.uk/pages/belts/poly_v/polyv_main.htm They are multirib belts, but are generically referred to as polyvee here, although I think that Polyvee is actually a trademark.

They coped with a bit of slip very well indeed, I had no significant wear or pulley heating problems with them. They seemed to inherently torque limit when faced with a sudden high-torque demand by slipping just enough to keep the peak torque below the point that would allow the torsional resonance to develop (this was on the prop drive).

Jeremy

 

[recumpence]

Yup, that is exactly what appliance (mostly dryer) belts look like.

They do take limited slip very well. The problem is, you cannot nail the throttle and let it slip up to speed. That would burn up the belt. They are fantastic at occasional pulses and limited slip in a system to dampen shock. They are also very good vibration reducers in a system. Most belts are good vibration dampeners. But, multi-rib belts are exceptionall good at this.

Oh, also, these belts require very little tension to achieve the desired torque holding spec.

Matt

 

[Whiplash]

I have seen true V belts in applications that allow slip up to speed, like in drill presses and such, you don't think they would handle the slip up to speed on a bike? I think they use the V belts in some of the smaller CVT transmissions and they definitely slip until the clutch engages fully....?? I see your point that they won't navigate a really tight corner like on a small pulley though, it would have to be two somewhat decent size gears.. Possibly from the final drive gear on the reduction drive to the front sprocket? If you were running through the gears...

 

[liveforphysics]

In my experience, any belt is a liability, and any belt that slips is going to fail at some point. A clutch that is designed to slip with proper wear materials at the friction point, and a spring for constant and controlled force is so much better than a loose belt, and it enables you to run a chain with it for ultimate reliability.

Non-toothed belts are tough enough to keep alive in the best of situations, then you add in asking them to slip, combine a sprinkle of rain or whatever... Just a total non-starter for me. If you wanna have some slip in a system (and there are lots of applications where it's good thing to have), do it with a part built for slipping if reliability is something you're looking for.

 

[recumpence]

I have seen true V belts in applications that allow slip up to speed, like in drill presses and such, you don't think they would handle the slip up to speed on a bike? I think they use the V belts in some of the smaller CVT transmissions and they definitely slip until the clutch engages fully....?? I see your point that they won't navigate a really tight corner like on a small pulley though, it would have to be two somewhat decent size gears.. Possibly from the final drive gear on the reduction drive to the front sprocket? If you were running through the gears...

You are talking about V-belts. We are discussing poly-V, multi-rib belts. I had the same misuderstanding too.

Matt

 

[amberwolf]

Since the topic came up, of polyvee/multirib belts: Both of the treadmill motors I now have use the same belt type and size, and have the same size pulleys (about 3:1 ratio). If I end up trying one of these motors out with high voltage (60-90VDC) on one of my contraptions, I'll need to use a hefty reduction from the high RPM of the motor to get a normal wheel speed.

In the very first drivetrain for CrazyBike2, which was not road tested due to lack of portable batteries but did work fine "on the bench", I had a freewheeling contraption I came up with to go from that belt to a small chain like an exercycle or a small scooter uses. The belt worked fine then, and I'm curious if you think it might work to haul something as heavy as CB2 around. It gave total about 30:1 reduction, between the two stages, to get me a normal pedal-speed input into the drivetrain of the bike.


FWIW, one reason I liked the pulley off the treadmill roller is because it happens to be just about exactly the same diameter as the typical Shimano 5- or 6-speed cassette's freewheel body, and just the right width, too, so you can take all the cassette's sprockets off, squeeze the pulley on, then screw on the outermost sprocket to clamp the pulley into place. If necessary, I'm sure bolts could be run thru the sprocket's tooth gaps into and thru the pulley, and/or epoxy could be used to glue the pulley to the freewheel body in addition to the screw-on-sprocket clamping force.


So, if the belt will slip just that tiniest bit if too much force is applied, that would make a great way to keep shock loading from causing too many other problems along the drivetrain (I hope).

Since the belt is the high-speed portion of it, it should help with noise and not have to deal with as much torque, as if it were the low-speed portion of the reduction.

 

[Whiplash]

I have seen true V belts in applications that allow slip up to speed, like in drill presses and such, you don't think they would handle the slip up to speed on a bike? I think they use the V belts in some of the smaller CVT transmissions and they definitely slip until the clutch engages fully....?? I see your point that they won't navigate a really tight corner like on a small pulley though, it would have to be two somewhat decent size gears.. Possibly from the final drive gear on the reduction drive to the front sprocket? If you were running through the gears...

You are talking about V-belts. We are discussing poly-V, multi-rib belts. I had the same misuderstanding too.

Matt

Ah, I see then... OK.

 

[olaf-lampe]

I agree with Luke, there are many questionmarks behind the use of a poly-V belt. ( but it's so damn cheap too )
I'm also couriuos to know how the slipperclutch behaves under wet conditions?
Probably the wheel is the first thing to slip then
-Olaf

 

[MitchJi]

Hi,

In the very first drivetrain for CrazyBike2, which was not road tested due to lack of portable batteries but did work fine "on the bench", I had a freewheeling contraption I came up with to go from that belt to a small chain like an exercycle or a small scooter uses. The belt worked fine then, and I'm curious if you think it might work to haul something as heavy as CB2 around.

Wether it will work or not will depend on the rib/grove pattern, the number of ribs (belt width) and the size of the small pulley. J-section and K-section belts look like good candidates:
http://www.transdev.co.uk/pages/belts/poly_v/polyv_main.htm
http://www.transdev.co.uk/pages/belts/poly_v/jpv_main.htm

J Section Poly V
Power Range up to 5 kW
RPM Range 0-10,000 rpm
Min. Pulley diameter 18mm

http://www.transdev.co.uk/pages/belts/poly_v/kpv_main.htm

K Section Poly V
Power Range up to 30 kW
RPM Range 0-8,000 rpm
Min. Pulley diameter 50mm

I agree with Luke, there are many question marks behind the use of a poly-V belt.

Luke didn't question using Poly-V. He questioned using Poly-V with slippage (in place of a slipper clutch). Assuming you can live with 5kW or 30kW the issue with non-slipping Poly-V as compared with toothed belts is pulley diameter and width.

 

[amberwolf]

Wether it will work or not will depend on the rib/grove pattern, the number of ribs (belt width) and the size of the small pulley.

I'll have to go find the belt (or check the one on the "new" treadmill I haven't disassembled yet) to see it's specs, but I think it's 8 ribs, roughly an inch and a quarter wide, and around 10-12 inches long. Large pulley (receiver) is around 3.5" and the smaller one (motor drive) is a bit over an inch in diameter (roughly 3:1 ratio).

It looks more like the J-section belt, for cross-section, IIRC, but again I'm not totally sure--it's been quite a while since I looked at it.

Small pulley is steel (well, cast iron) on the first treadmill motor I'd gotten, and I think it's aluminum on this newer one. Larger pulley is plastic of some type on both of them--they appear virtually identical, actually (from memory, not a side by side comparison, yet).

One thing I do recall about these belts is they do not tolerate any misalignment, unlike a regular V-belt.

 

[olaf-lampe]

One thing I do recall about these belts is they do not tolerate any misalignment, unlike a regular V-belt.

It's the same story with HTD belt, right?

I have some poly-v pulleys with integrated magnet clutch laying around from unused AC compressors. Maybe I try that route and see how much power the mag-clutch can take. I guess it's not much
-Olaf

 

[amberwolf]

It's the same story with HTD belt, right?

Not necessarily--if you have sides on the pulleys, those could be misaligned somewhat and still remain seated on the pulley, though they would wear faster.

THe multi-groove polyvee/etc will jump over a whole groove as soon as it is misaligned just a little, and then again, and again, until the edge of the belt is either rubbing on the face of something preventing further lateral displacement, or it's jumped off the pulley. That happened a few times before I got it right on my first CrazyBike2 experimental drivetrain.

 

[slowbuild]

fantastic work Matt - I'm very interested in obtaining 1-2 of these when you are ready. Can they be retrofitted to
existing MS drive reduction units - thinking of the 3210 10:1 and 3220 4:1 units?

regards

 

[MitchJi]

Hi,

fantastic work Matt - I'm very interested in obtaining 1-2 of these when you are ready. Can they be retrofitted to
existing MS drive reduction units - thinking of the 3210 10:1 and 3220 4:1 units?

With one washer, it adds about 1/2 inch to the width of the drive (1/2 inch added to the belt drive width). It would be more compared to a chain drive unit).

The only potential issue is the extra width required at the end of the large primary pulley or sprocket.

 

[MitchJi]

Hi Matt,

I even let my aunt ride it yesterday. I just told her "Here are the brakes, this is the throttle. Pedal to 5mph, then you can use the throttle. Have fun!"

Matt

Is that the reason you don't have any issues with start-up with the Castle esc's (you always Pedal to 5mph before using the throttle)?

If so it seems like reasonable limitation to me (unless you are forced to stop on a steep hill with a heavy load).

 

[recumpence]

No, actually, the main issue with dead-stop starting is more related to motor pole count and gearing. I have found the Astros do not like to start up as well from a dead stop than my Plettenberg. However, that is the difference between an 8 pole motor and a 20 pole. Also, the higher KV a motor is, the more willing it is to start up from a stop. At this point, I never start up without pedalling first just to be kind on the controller.

Matt

 

[spinningmagnets]

I suspect the peak amp-draw on acceleration has been lowered and smoothed-out a significant amount. Beautiful work!

 

[recumpence]

One thing I love is being able to run a belt drive with a 3220 if I want without ruining the belt.

Right now I am running a 6 turn Wye 3210 geared way down through the clutch. The clutch rarely slips. I have to really get on it to slip the clutch. But, the clutch is there to take the abuse, should I dip too hard into the throttle.

Matt