Slipper clutch

Hey Guys,

I mentioned this in a previous thread. However, I did not want to derail that thread on this subject. So, I will elaborate here;

Here is a picture of a slipper clutch I have on my Catrike 700-E. This is basically an off-the-shelf clutch I made a pulley to fit. There are numerous reasons I chose to do this;

#1 Driveline protection. These motors have HUGE torque and I wanted to protect the driveline from over torquing it.

#2 To eliminate belt skip on belt drive systems.

#3 Reduce harsh accelleration "Slamming" the bike forward. This gives a much smoother accelleration.

#4 Allow beginners the opportunity to ride my bikes without worrying about them being too harsh with the throttle.


This clutch succeeds 100% on all those points. I have been letting nearly everyone I know ride this thing. 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!" She pedalled 20 feet or so and (sure enough) she nailed it! But, no worries, the clutch happily just gave about 6 or 7 seconds of slip while the trike evenly accellerated up to speed. She turned around and, same thing, she pinned it and came to a stop in front of me with a huge grin on her face "That is really FUN!" she said! So, I figure, anything that awakes others to the bliss of the EV grin, is great by me.

Anyway, this is a very reliable clutch that is easy to adjust and retains a very consistant level of slip over a large RPM range and over a duration of time. I have run this thing in various temperatures and humidity levels and the tension/slip remains consistant.

I will be offering this clutch to my drive unit customers very soon. It will come with detailed adjustment instructions. It is really quite easy to adjust, though it takes a few test runs to get it just right.

Matt

That is awesome. You have an almost idiotproof system. A lot less worries that someone will tear it up because they don't understand how to finesse the system.

nice one Matt

I let a couple friends ride my bike yesterday. the only instructions I gave them was "turn the throttle slowly." they both quickly twisted the throttle and hit the amp cut-out.

If I ever get lipo I'm going to want one of those clutches

Hi Matt

They look like a great idea!! and I can think of a certain person with a very sore arm at the moment that may consider that to be a good idea!! do you think it will be ok for his off road antics, Deecs style of riding will be short bursts or speed I think.

Knoxie

Matt,

This is an awesome find! Great to hear it has worked so well and so easily. This may be one of the final links in the RC drive chain. If you can put anyone in the saddle and let them rip without fear of braking things, then those of us that are pushing the limits can push them even further. I can't wait to see one on a mtb build.

Clay

I have dreamed it that night ... made by Matt this morning ! Is anybody has ever called you GOD ?

Hi Matt,

How much width does it add to the drive?

Doesn't fit in the enclosure?

Any idea of the price?

I will be offering this clutch to my drive unit customers very soon.

Click to expand...

Available by itself also?

Override switch?

very cool matt. what material are you using for the clutch discs and spring?

OK, let's see;


The price will probably be $100 added to a normal drive unit. That is just my cost on the clutch and time to make the minor changes to the drive for use.

The friction material is a semi metalic, fiber pad. The drive plates are ground steel. The spring is a Belleville (spelling?) washer. They can be stacked in series or parallel for more or less tension.

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). It can be used with the case if I make a case that is extra deep for the clutch. It does not need to be alot deeper case. But, it would need to be wider, none-the-less.

I am still hammering this thing. It just works, no problems at all!

Matt

Great work, Matt. Another excellent engineering solution, thinking ahead long before customers have a problem. You are the anti-corporate developer.

Neat! Slipper clutch has got to kill 2 birds with 1 stone so to speak. Bike start up is more beginner friendly, torgue, rpm, & amp draw smoothed out;

Does the clutch supplant the driveshaft FreeWheel?

You did a really nice job with that Matt.

SoSauty said:

Neat! Slipper clutch has got to kill 2 birds with 1 stone so to speak. Bike start up is more beginner friendly, torgue, rpm, & amp draw smoothed out;

Does the clutch supplant the driveshaft FreeWheel?

Click to expand...

No, the freewheel is still there on the other side of the jackshaft.

Matt

Matt, About what rpm does the clutch engage? Does it fully lock up at a certain rpm? Is it a centrifugal clutch? I have been looking at using a centrifugal clutch to alleviate the no pedal start issue. Thanks, -Damcard.

To answer the previous posters question, I believe it's adjustable (given the name) and thus you can adjust the spring tension to have it "disengage" at the proper torque limits...

I suppose poor mans calibration would be set the clutch far lower than needed, test - if no belt slippage, increase the torque level it breaks loose at and test again until slippage occours then back it up just a tad.

Sorry if I am way offbase with this Matt - I just assume these are the same types of Slipper clutches we used in GoKarts built back in the day (and no I'm not confusing cyntrifigual even if I can't spell it).

Matt a question - what weight and side if any does the slipper clutch add to the assembly of the large diameter HTD pulley - it looks as if in the end there is no net dimensional gain but I wonder if there is offset, reduction or increase in mass of that pully with the clutch embedded.

That said - whats your lead time to provide me a Slipper clutch embedded in the large sprocket to fit my v3 gearbox, and I'm sure you've been asked this tons but how about the price? Could you please commit me as in for a minimum of 1 of these?

I have some fit and finish questions with regards to teh v3 drives - and perhaps a method of improving (if there is not a structural reason for part of the machine work) the fit on bikes with very tight clearances... what thread should I post the feedback to?

Warmest thanks!

Mike

Mike,

You are correct. It is a torque limiting slipper clutch, not a centrifugal clutch. It is adjustable as well.

The clutch adds nearly a pound to the drive. That is because it is solid steel. This is not an item we make from scratch. It is something I purchase and modify for our use. It could be made in aluminum. But, there are a few issues with that (more than I could get into here). So, the extra pound is no big deal from my end, though it may be for someone else.

I figure it will add $100 to the price of a drive. That is if it is ordered with a drive. If ordered afterward, the cost would be higher because part of that $100 is the drive pulley or sprocket that a drive would have included anyway.

There is an increase in part depth. However, I can reduce that somewhat. So, the net gain will not be much at all, exactly how much, I need to measure yet.

I have a bunch of pulleys in stock to be lathed up for clutches and one clutch in stock. I will be ordering more clutches soon. My guess is, about 2 to 3 weeks and I should have clutches to sell.

As for the V3 drive dimentions, there is a way do decrease the Q-factor. However, other dimentions are restricted for various reasons that are tough to describe here. There are some other drive system ideas I have in my head right now. But, nothing to share at the moment.

Matt

this seems interesting, a video showing it in use would be nice, would it be possible to make a standalone version of this type, or what benefit would there be to combining the two types besides being able to reuse the big pulley

Sorry, if I butt jump this thread, but I came up with the idea to use a poly-V belt for transmission and also as torque-limitter.
Would it be possible to adjust the tensionroller to limit the current? Will the belt survive occasionally overload?
I'm afraid the belt will not slip continously and will create a huge torque/current ripple for the controller?!

I'd be happy if it'd work. Pulleys, spring tensioners and belts are almost for free on every scrapyard

Any opinions?
-Olaf

olaf,

While not as "elegant" as the slipper clutch matt is machining into the large 5mm htd pulley - v belts with spring tensioners have been used for years and yes they will likely slip the question is will the break, I would caution a guess that under real serious power they will break however given the spring tensioned nature, replacement with a spare should be a 3 minute roadside job at worst I would think and weight may be slightly better than 1 lb but I am guessing at the weight advantage.

I've gotta say, as a proud new owner of a v3 drive... adding the slipper clutch would be like, 1 lb of prevention could well be equal to 1000$ of cure

Really it may be an adhoc (after the fact) idea or design integration (though he always had a slipper even on v1 recumbent) for these, it is actually a great solution to:

Chain impact on throttle up
Controller overload prevention (a big issue for many as we know)
Broken belts
Spoke fatigue

In fact, it's basically a mechanical current limiter for the controller and a mechanical force protector for the driveline - at 1lb center mounted additional weight, well you do the math _

-Mike

I agree it's not elegant
But I don't see why it should break? There are lots of devices mounted on a single poly-V belt like alternator, waterpump, AC-pump and powersteering. This summs up to some kW I'd say...
I thought the belt would start to smoke and burn when it slips too long?
-Olaf

It sort of works. I built a propeller reduction drive for a light aeroplane years ago that used a polyvee belt for just this purpose. Originally I'd used an HTD belt, but had problems with the prop inertia causing a spot during acceleration that caused torsional resonance (the engine was a V twin with widely spaced torque pulses and a light flywheel) . Switching to a polyvee belt drive eliminated the problem, as the belt slipped just enough during the torque pulses to allow the engine to accelerate through the resonance and into the working rpm range.

Jeremy

Good news Jeremy,
Would be worth a try, since I could build it cheaper than shipping of a slipper clutch would be from US.
Instead of just a spring tensioner, i could use a break lever as clutch to loosen the tension from stillstand.

Does a poly-V tend to jump off, when its to loose?
-Olaf

No, they are pretty good, Olaf, and close to being as efficient as an HTD belt. I had no problems running one at around 30hp continuous for a few hundred hours. It only slipped during acceleration, just when the drive went through resonance, and wasn't particularly loose. I'm pretty sure that a variable tension polyvee belt drive would work pretty much like a slipper clutch and be reliable enough for a few hundred hours of use on a bike.

Jeremy

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