Possible slipper idea??
 

OK, don't laugh!

I was looking at my H8 with the "prototype" motor on it using the clutchbell and started to think of an idea about making a compact slipper for buggies using the clutchbell (or something similar). I mean, a Nitro engine uses the clutchbell as a reverse slipper really. You just have the make it so the clutch applies pressure all the time but allows to slip when needed instead. It would be nice to have a compact slipper setup for use with centerdiffs.

After some measurements, I came up with something to start with: Cross-section view of CB slipper

Excusing the crude drawing (using Excel with some Paint Shop Pro touch-ups); basically you have the clutchbell (black) that is coupled to the center shaft by the spring loaded slipper pads (blue) pressed into the inside of the bell via the springs. Since the motor shaft is not long enough to extend to the needed depth, an extender is used. This design allows you to still slide on the bearings (green) and is held with grub screws (purple-ish).

Yeah, it looks dumb and there are some flaws to this design. But I think there might be some merit to it. The biggest problem is to get the shaft extender to fit inside the CB opening and still use bearings. Even using 6mm X 10mm bearings (for the largest inside opening), there is only 1/2 a mm for the "walls" of the extender at one point since the motor shaft is 5mm in diameter. If the CB opening could be bigger, the extender should work.

Anyway, it's just an idea, so be gentle! :dft001:

Ive always had my Nitro sniffing mates telling me they don't need a slipper, because the clutch takes the strain off somewhat.
being a soft link to the transmission it is.
I have wondered about utilising a clutch system myself.
are you going to build it Brian?

No, I'm not going to build it. I don't have the tools (or cash) to attempt something like this. I'm just trying to throw ideas out there in the hopes someone with the time, capital, and tools wants to try it. Or at least maybe inspires something else that might work.

It just would be nice to have options. Mike will have the slipperential out shortly (??), but that looks like it's more for custom applications or using the GMaxx chassises (or is that "chassi"?). Other applications can use the Revo-style, Strobe, or Robinson Racing slippers. Buggies tend to be a little short on room and the center diff doesn't leave much room for any of those.

You should see if Mike would be able to make it just for testing. It would certainly be an alternative to the slipperential, with less weight and complexity.

At one point I had the idea to make a slipper-diff in place of the center diff. It would have a custom spur gear mount (in place of the Hyper 7/8 spur gear) that would have a slipper clutch built into the back of it. Some time I should attempt to draw it up in Solidworks.

I think he has idea's for a Truggy/buggy 'slipperential' (begging for a trademark)
As winters coming, lets hope he has some more 'Lab time' as I have a CRT/Jammin just waiting for it.

and yes it is ist's chassis :dft012:

MM: I'd like to see your idea for the slipper on the center diff. If it would fit in between the stock diff mounts, that would be nice.

I was just trying to come up with some type of "bolt-on" part that was small and easy to fit. A little outside the box maybe...

It wouldn't fit inbeween the stock diff mounts, since it attaches to the plastic diff housing and extends away from the diff. In some cases, it might be the right size so that the shorter center-front dogbone could replace the longer center-rear dogbone, assuming that your buggy works like that (my XTM-Xterminator does).

Your idea would certainly be the easiest bolt-on slipper out there (you would literally bolt it on :) ). It's an interesting idea, something I had never seen before. It would be nice if someone could experiment :).

It is an idea, but i think it will be too expensive to have in production Brian.

And you will have the problem again with wearing pinion. Less because of the slipper, but still.

And i doubt if .5mm of thickness is enough

You could push the slipper out farther so that the motor shaft is not in the clutch bell gear. That would solve the wall thickness problem. You could also flip the clutch bell around. This would cause a clearance issue with the setup you show but you solve that by flipping the diff. around (at that point the gray shaft might have to be extended a little).

That wouldn't help really. you don't want the pinion to stick out too far. And besides, i think it will be allmost impossible to get a proper resistance on the slipper at those high RPM's it's running on. (low torque/ high rpm is hard to build a slipper on)

Why couldn't you just mount a typical 3 shoe nitro clutch on the shaft of the motor. You woulnd need an adaptor of some sort, but sesides not being able to use the motor to brake, what is wrong with just using a standard nitro clutch?

I don't think a standard shoe clutch design would work well for two reasons:

1) The clutch engages only at a certain rpm to allow the engine to idle without stalling. We don't need that with electric for obvious reasons. Another function of the clutch is to allow engine rpms to rise enough where it develops some usable power. Again, this isn't needed for electric.

2) The centrifugal force pushes the shoes into the bell harder and harder as rpms increase effectively locking it. High rpms is where you want the protection. The stock setup will grip the hardest at the high rpms and will offer virtually no slip. I wanted a slipper with an even amount of slip no matter what rpm it is spinning at.

Flipping the diff and mounting CB in the standard way sounds like the best idea so far. I'll work on a V2 when I get home and post the result.

Thanks for the feedback guys!

OK, here's the same basic idea with the CB facing the "right" way. I didn't touch this up in PSP though, it's just a direct Excel screenshot (OK, I was lazy). This one is nicer in that there is not thickness problem, and you can use regular 5X8mm bearings. Securing the motor shaft might be a little hard to go to though - maybe a small hole in the CB to allow an Allen wrench to get in there?

looks better that way. how do you adjust the tention?

What about moving the slipper pad to the flat inner face of the clutch bell and using a conventional spring and nut to adjust slipper tention.

Something like this.

http://i66.photobucket.com/albums/h2...Assembly-S.jpg

For the tension, there are spring-loaded screws, probably four in all. The springs are the red dots - remember, it's a cut-away view. The problem with this is you have to have the CB seperate from the hub to adjust the tension, then have to muscle it back in the CB. Then again, you generally don't want too much slip since it's really intended for drivetrain protection so there shouldn't be much adjustment. The screw part could be eliminated, but then there would be nothing to stop the pads from gripping harder at high rpm due to centrifugal force (same problem as with using clutch shoes, mentioned earlier). The springs provide the force, the screws provide the limit.

It's hard to make stuff in Excel (but much faster) so it might not be readily apparent.

This version looks much easier and cheaper to build.

That looks good, but would there be too much stress on the bearings essentially shearing them apart (the CB pushing out while the hub is being pushed in)?

BTW: I'm glad there are others tying to think of a way to do something like this! It doesn't even have to use a CB; I just decided to try it since I had one on hand for measurements.

You could make little spacers that would stack up and contact only on the inner ring of the bearing. Esentially makeing a solid column to support the load. Than the balls in the bearing would not take the load.

This was just a rough concept sketch. There would be plenty of details to work out.

I think that something like this could work though.

Well, if the bearing load thing can be worked out, this could very well work. Like I said; we don't need a clutch, we need protection for the drivetrain - something has to give. So, as long as the slipper will give only at a certain amount of resistance, it'll be golden.

Another CRAZY idea I was thinking about: magnetic slipper. I have a couple magnets I pulled out of a dead harddrive and they are CRAZY STRONG! They can support their weight (with a metal plate attached to them) throught the thickness of my hand. So, put a series of small magnets really close to each other (~0.5mm) in something like a clutch bell. I'm thinking it will be essentially locked unless some kind of outside force breaks them loose. And best of all, no heat when they do slip.

Again, I'm just thinking out loud here...

Id be a little concerned about putting magnets that powerful that close to the magnets in the motor. Who knows... Maybe they would cancel each other out and you would loose power in the motor.:005:

Seriously though. I think that magnets would weigh an awful lot. Remember, adding weight to the pinion has a MUCH larger effect on the total rotational mass than adding weight on say the wheels.

A crazy Idea I had was wanting to design a slipper clutch that worked like the keyless chuck on a power drill (but smaller obviously). Having numbers around the outside and you just hold the spur and rotated the slipper to dial in your desired tention. That way when you found the tention that worked, you could always go right back to it without guessing.


BTW: So when are you going to start working on the prototype of this slipper idea???:p

Just thought of another thing to worry about with any of these slipper designs. The heat generated by a slipper would be being transfered to the motor shaft and into the motor. I'm not sure if its enough to worry about, but the motors generate enough heat already. We don't need to be adding more.

True, but only if/when it slips. The idea is to just provide drivetrain protection, so it shouldn't be slipping that often. It is a thought though.

I really like this idea as it would eliminate our troubles with pinions and gearing since we could use standard clutch bells. My only concern from heat would be fade from limited contact area. With a center diff you don't really need much slipping action, so that wouldn't be an issue, but on the monster trucks where some slipping would be beneficial aside from just protection I would worry about heat generation.

This thread talks about the hardened steel pinions and Mike's view on them. I'm thinking that a slipper would go a long way to make those pinions wear better since there would be some give with some form of slipper.

I'm not sure about the potential heat issue. Nitros use the clutch a lot harder since it slips most at low rpm. The heat is caused by the rubbing surfaces when there is slippage. As long as the hub and CB spin at the same rate, there is no slipping, therefore no heat.

I wonder what Mike's take is on all this? I'd be curious as to what he thinks.

The magnets would have neglible effect on the motor magnets. Having magnets coupled together like I'm thinking of provides a path for the vast majority of the magetic flux to flow. Very little flux should be present within an inch away, at least not enough to affect the motor in any way. As far as the magnet weight is concerned; I see your point. That weight would act like a flywheel of sorts and might reduce motor spin-up. Hey, it was just an idea.

The drill chuck idea may be an alternative. I have no idea how that works though since it seems to rely on some type of ratcheting resistance. Making as small as it would need to be to fit in the sapce allocated may compromise its strength.


Keep the ideas coming. :)

Nitros also have much more contact area in their clutch than the above drawing. I admit I didn't look at yours close enough. As long as contact area was equal to or greater than a nitro clutch (as yours shows) I would not be concerned about heat.

I still don't think any effective drive gear solutions exist as abundantly (and therefore inexpensively) as clutch bells.

Don't forget; my drawings are crude cut-aways. I was thinking of having four seperate fairly large pads covering the majority of the CB depth, which should approximate the amount of suface area of clutch shoes.

Yeah, there really isn't anything for buggy conversions yet, hence this thread.

I know this is an old thread but all you slipperential needers need not worry. A drop in slipperential solution for all center-diff equipped truggy/buggy's is near. Stay tuned.

And if you have a CRT conversion , you're gonna love it even more.

Here's a peak at my Jammin CRT conversion I am working on. Look close and you can see the next-gen slipperential Mike and I are working on.
http://i116.photobucket.com/albums/o...inlayout4a.jpg

that would be the slipper-diff wouldn't it.....mike explained it to me on the phone once....I can't wait to see this.... by the way nice renders....

don't know what others call other things, but it is a differential with slip... so I call it a slipperential. Just makes sense!

yeah but with so many slipperential's that are gonna be made...they are gonna have to be designated.....
slipperential V1- gmaxx
slipperential V2 -g2r
slipperential V3 - buggy/truggy

wow it's starting to get confusing....lol

Then let's call this a direct drive slipper. Cause there's no more need for top shafts/gears, idlers, etc....

With all the versions of the slipperential, it's starting to sound like a Rocky movie!

How about slipper-diff? That's what I called my version way-back-when. It's distinctly distinguishable from slipperential :005:.

lol, that's funny......starting to sound like a rocky movie....lmao