Are Open-Diff Chain-Drive Axles a Thing?

Willie1

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I don’t see why you could not build one from a pto torque limiter. Just need to make sure it is balanced real well for high speed.
Not familiar with those, but I'm sure it would be the same concept as I drew. We used the couplers I showed building
conveyors, stackers and such in the corrugated industry. While we used them as torque limiters to protect chains and
shafts from breaking from shock loads, they were pretty durable and rebuildable. They are basically a self-resetting
breakaway clutch.
 

Denny

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Yup, almost the same thing except the ones I’m talking about were only about 60 bucks at Tractor Supply. Last time I checked years ago. They fit on a tractor pto to run different implements. Generators, log splitters, saws for lumber grain elevators and on and on.
 

Willie1

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Yup, almost the same thing except the ones I’m talking about were only about 60 bucks at Tractor Supply. Last time I checked years ago. They fit on a tractor pto to run different implements. Generators, log splitters, saws for lumber grain elevators and on and on.
I think we are on the same page. The clutch itself was about $80, and there were other style and cheaper ones. Then there is the cost of the sprocket that goes into it, 3 other keyed sprockets, the keyed shaft, side bearings, chain, etc.
I'm sure if someone was really interested in doing something like that they could shop around and cut costs.
I was just showing a "concept" and wasn't going to waste (more) time price shopping on something that likely wouldn't be built anyways.
 

Willie1

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Im currently building a 6 wheel buggy with duel rear diffs. Its not too bad to make. Midwest Miata has one in stock for $50 right now. I found two for $25 per on there. Pricey shipping however. With the miata setep, you could manually switch to a solid axle if you were to unbolt the diff setup, and bolt in a solid axle/sprocket in its place. Not fast, but its possible:
.

I used low temp aluminum weld rods for my can lids.
I've seen several builds using the Mazda diffs, because they are small, reasonably cheap, and their shape lends itself well to making a shell to seal it up. But, they are hard to find with a limited slip diff - if one is even offered, and I think the primary reason for this post was to find some sort of way to make a limited slip or a selectable locking axle.
 

l008com

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A torsen or tru-trac style LSD should more or less fit in the same size case as the pearson 100, be more or less the same weight, and be the perfect solution! For people that do crazy off road stuff anyway. The more I think about it myself, the more I think an open diff will be just fine.
 

Willie1

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A selectable locker is whole other headache!
I'm pretty sure if (IF) I was properly medicated I could convert a Peerless 700 style trans to selectively lock a pair of
output shafts to drive axles in the manner I showed above with the torque clutch.
 

l008com

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I was reading about the pearless 100 axle which directed me to the pearless 700 transmission and i have many questions about it. I was going to start a new thread but I guess I can just post them here?

How does this thing work?? There's no clutch! Do you have to add a clutch? Can it be shifted without a clutch? Is it like a riding lawn mower where you can't shift at all while you're moving so it's not really a transmission in the traditional sense?

I watched a bunch of videos on how it's constructed and it looks like even with a clutch, it has no synchros so it looks like it would grind like crazy shifting.

But that transmission is exactly what I've always wanted in a go kart. 5 forward speeds plus a reverse! My stupid kart has no reverse. If I had a dollar for every time over the past 20 years i've had to get out and push myself back to get unstuck, i'd have two Dingos!

An idea setup for me would be to have gears 2 thru 5 set up like a 1 thru 4, and then the first gear would be a super low range. So you could use 2 thru 5 for normal screwing around driving, but dump it into 1st when doing some crazy hill climbing or towing trailers or other tractor-like tasks.

The other thing I don't quite understand is that the input shaft appears to be 90° to the output shaft. Also there are two output shafts? So how would you build this into a simple manco style kart arrangement?
 

Willie1

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Power goes into the bottom through a drive pulley and out the side with a chain sprocket. The clutch is done through the drive belt - tension is applied/removed with an idler pulley. You CAN NOT shift them while moving and expect them to live.
Some have output shafts on both sides where they mounted a brake - most don't.
 

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l008com

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Gotcha, well that kills that idea. I guess ill be keeping the commet. I have seen many forward/reverse mini gearboxes where the reverse is a lowered 3:1 gear. Are there any simpler gearboxes like that that have a 1:1 forward, 3:1 reverse AND a 3:1 forward? A 7 HP motor to a commet 30 to a 3:1 low ratio gearbox would give me plenty of working power. And the normal 1:1 drive gear would give me plenty of screwing around power :D
 

Willie1

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The typical F/N/R gearboxes are not 3 to 1 - they are 1.3 to 1 in forward, and 2.6 to 1 in reverse.
 

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l008com

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So I've been thinking about this and this gearbox is out as far as being a primary transmission. But the gears/gear ratios could be customized right? So could I buy that transmission and configure it as a low range reverse, low range forward, 1:1 forward 3-speed gearbox, connected to the comment belt drive the kart has always had. That would actually be ideal! But I'd still have the issue of the axle shafts, I'd need parallel axle shafts for that, not 90°x90° input output shafts.
 

Denny

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Only if you are a machinist! Jeffco or RPM boxes come with custom gearing. You could get one of those. But be prepared to pay!
 

Kartorbust

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Well the Jeffco and RPM gearboxes are kind of customizable, they have their own sets you can choose from.

If you have access to a lathe and mill, you could make your own gear sets. Or you could look for a blown up four wheeler and snag the gearbox off of that. Just need a primary clutch that will match up with the secondary.
 

Snaker

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Yup, almost the same thing except the ones I’m talking about were only about 60 bucks at Tractor Supply. Last time I checked years ago. They fit on a tractor pto to run different implements. Generators, log splitters, saws for lumber grain elevators and on and on.
There are two types of tractor PTO "clutches" that I know of.

Slip clutch: That is essentially a resettable and reusable replacement to a shear pin.
They have a stack of steel and fiber plates controlled by adjustable springs similar to a motorcycle clutch.
But they have a very limited life of slipping, as in minutes because they never actually disengage. They slip.

Overrunning clutch: This is attached to the PTO driveline and lets a flywheel type load continue to spin after the tractor PTO stops.
Handy for spinning mass' like rotary mowers or various large fan type equipment.
I believe that they are a type of Sprague clutch design that locks in one direction and freewheels in the other direction.

I could see the overrun clutch working for this project, theoretically.
Mount one on each axle.
In a turn:
The inside wheel would still be forced to turn under power.
The outside wheel would be getting the same power but would be allowed to freewheel faster than the power being applied.
So, if the leverage worked out, the outside wheel would turn faster than the inside wheel.
Would that fix the scrubbing issue? Maybe not.
I'm not sure about the direction of rotation involved.
That would also mean no reverse, no engine braking, etc.

MIS138 PTO Over Running Clutch 1 3 8 1 3 8?utm_content=|pcrid|80882837094306|pkw||pmt|be|slid||pdv|c|product|MIS138|pgrid|1294125241984847|ptaid|pla 4584482451756166|%20to%20https%3A%2F%2Fwww.steinertractor.com%2FMIS138 PTO Over Running Clutch 1 3 8 1 3 8?utm_marin=|pcrid|80882837094306|pkw||pmt|be|slid||pdv|c|product|MIS138|pgrid|1294125241984847|ptaid|pla 4584482451756166|&msclkid=e9cc01aab48a10eb5c02620582e970cc&utm_source=bing&utm_medium=cpc&utm_campaign=(ROI)%20Shopping%20 %20PT&utm_term=4584482451756166
 
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jmaack

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Yeah, I had a 3 wheeled trike (Tri-Sport?) years ago that had a similar setup. It had a brake lever on each side of the handlebars that operated a drum brake on it's side of the trikes rear tire. It was fun to grab the inside lever for turns, but kinda hard to use in mud. You pretty much need to run disc brakes to do that with any effectiveness - it's hard to control the self-energizing effect of drum brakes wrap around band to control the slip of the drum to give resistance but not lock up the drum. Discs are much easier to modulate.

So, yeah - that is another option that is more cost effective that the one I suggested. Setting it up with one control to operate both brakes and another pair to run the brakes individually would be the tricky part. Easier to do that using cable operated discs than hydraulics. While as I suggested, the system I drew up is expensive and slightly complicated - it also is automatic system that you don't have to operate separate controls to make it work. But I've never seen anyone here suggest anything
like it so I just wanted to show a new idea.

Again - bored - drawing.
If I was going to use the brakes to work as you suggested - here's how I would do that. Use a foot pedal to control both brakes - you will need more pressure to apply both brakes than would be comfortable by hand. A cable or rod would pull in the center of a floating balance bar - this would apply both brakes. The front levers could be mounted as the builder chooses -
levers on the sides of the seat, on the wheel, etc. Applying either and it just applies that side brake - the balance bar needs to be able to slide up the apply rod or cables so it won't interfere with the other side. Obviously you are using mechanical brakes - hydraulics would be hard to make this work.

Again - just a proof of concept drawing - not to scale.
simple term tractor brakes. Work flawlessly
 

l008com

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So i was poking around the Pearless website and found a different item they make that looks very interesting:


Open differential, with a locking option.
Input shaft and axle parallel so you can run it in a go kart configuration with a comet torque converter driving it.

There are two issues with it though. Three if you count price, I'm sure it costs a fortune.
But I'm not sure where you would put a brake rotor on this thing?
And second, the gear ratios are insanely low (or high?). 25:1 thru 5:1, and 61:1 reverse?? It makes me think I'm not understanding something about how gear ratios work or are presented here.

Edit: further reading, it does specifically say it can run off a comet 30, which is what my little 6.5 hp kart has. But then it also says its output torque is 450 ft lb. My big V8 truck only dreams of outputting that much torque. Can someone make sense of all these wild numbers?
 

Willie1

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So i was poking around the Pearless website and found a different item they make that looks very interesting:


Open differential, with a locking option.
Input shaft and axle parallel so you can run it in a go kart configuration with a comet torque converter driving it.

There are two issues with it though. Three if you count price, I'm sure it costs a fortune.
But I'm not sure where you would put a brake rotor on this thing?
And second, the gear ratios are insanely low (or high?). 25:1 thru 5:1, and 61:1 reverse?? It makes me think I'm not understanding something about how gear ratios work or are presented here.

Edit: further reading, it does specifically say it can run off a comet 30, which is what my little 6.5 hp kart has. But then it also says its output torque is 450 ft lb. My big V8 truck only dreams of outputting that much torque. Can someone make sense of all these wild numbers?
Looks to me to be a variant of a Peerless riding mower transaxle, and probably has a lot in common or shares parts with a Peerless 700 transmission. It mentions 2 or 4 shift keys, which the 700's had the same option - if it is the same style key, shaft, and gear setup, you can not shift it while moving without rapid wear or damage.

As to the torque output - your 450 ft/lbs truck engine can easily end up with 8000+ at the rear axle after the torque multiplication of the converter, trans, and rear axle. Your 6.5 hp engine probably has about 8 ft/lbs of torque.
A Comet 30 can double that giving you 15ish. Multiply that by a possible 25:1 first gear gets you about 375 ft/lbs,
and when you use the 61:1 ratio of reverse you are at over 900 ft/lbs available!

IMO 1 big red flag is the 2000 RPM input shaft max. Once the Comet 30 "shifts" it is around 1:0.1 or so, meaning the driven pulley is roughly at engine RPM - at WELL ABOVE 2000 RPM! I think the success of using one of these depends on how well they tolerate being "over-sped".
 

l008com

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If its a "gearbox" i'd be using with a comet, then I wouldn't need shifting on the fly. I'd be more than happy to have a setup where i can stop and shift from reverse, to low to high, then hit the gas and have fun. And being able to log or unlock the diff, also while stopped, would also maximize the utility aspect of the kart when i'm trying to do work with it and the fun part of the kart when i'm just screwing around.
 
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