Limited Slip Live Axle

[Functional Artist]

IMO live axles SUCK
…on heavy karts
...or with big wheels
…& especially on paved surfaces

Differentials can solve this problem
...but, they have their draw backs too (extra weight, additional losses, added cost etc.)


I've seen folks who have removed (1) of the keys, that lock the wheel to the axle (so, it freewheels)
...but, since there is no bearing between the rim & axle it, there is usually a huge wear factor
...which eventually destroys the rim &/or axle

I've seen variations of modifying a live axle so it allows (1) wheel to "slip" a bit, when necessary

Remove the key out of (1) rear wheel
...but, instead of just letting it "freewheel", add a spring (around the axle) between a keyed hub (sprocket, brake etc.) & the keyless wheel

This would/should apply rotational force to the keyless wheel 99% of the time
...but, would/should be able to "slip" when the wheels are rotating at different speeds (like in turns)

* The amount of pressure should be easily adjusted
...just by tightening or loosening the wheel nut.

** Maybe could even add a "friction disc" (brake/clutch like material) between the spring & hub
…& also maybe another between spring & rim (for additional "grip &/or even to reduce wear)

*** If the wheel & axle rotate at the same speed 99% of the time
...the rim to axle wear should be kept to a minimum

 

[mckutzy]

Cool idea..
The concept is called a slip clutch...

They use these things on tractors, various large cutting/grinding machines..... what ever machines need a stall protection from a jam of sorts...
The motor will keep going, but need to be protected. Large electric motors will catch on fire if not, transmissions will break ect...

As I understand... the key is getting the right springs and friction material to work together..

 

[itsid]

...but, they have their draw backs too (extra weight, additional losses, added cost etc.)

weight: ~3-5 lbs perhaps (would have to take it apart to know for sure)
slippage: not noteworthy [>99.8% efficient]
costs: ~ 100 bucks new (I paid less than 40 for a used peerless 100)

if you can beat all of that.. great, but a slip clutch is way less efficient,
so yeah.. one of three is out already
I wonder about the rest.

'sid

 

[Kaptain Krunch]

I dont think your system would work well on an off road kart, or a higher powered kart. Maybe for on road, lower powered it would function as intended.

Relying on a clutch pack to transmit ALL the power to one wheel, is a recipe for disaster IMO. I would just go with a one wheel drive, or open differential.

If i really wanted the best of both worlds, i would integrate a ratcheting system on both rims, allowing the outside wheel to spin faster while cornering.

 

[Kartorbust]

I think the idea is good, however I'm skeptical on how well it could be executed. I think running independent left and right brakes on a Peerless 100 would give better results and probably less complication.

For high horsepower vehicles, probably a generation 1 Miata rear differential with the ring gear swapped for a sprocket or same thing with a Subaru differential. My Blaster is a pain to turn on pavement or really anything while being pushed, but once its moving under it's own power, I have very little issue getting it to turn at low speeds on any terrain really. Still a live axle, just different application.

 

[anickode]

Wheel hubs with one-way needle bearings on a live axle. 100% power delivery in a driving situation, even with one wheel off the ground. Still allows outside wheel to overrun the inside in corners.

You just don't get any engine braking, or braking through the axle. Would need to run hub mounted brakes similar to a one-wheel-peel kart, but on both sides.

Alternatively, you could use a split rear axle with standard wheels, hubs, and brake discs (one for each side), and dual drive sprockets with sprag bearings. You still wouldn't get any engine braking, but you could use axle mounted discs. Same principle, but more conventional parts.

Or you could get real fancy and machine a differential-like housing that holds half-shaft axles, with a single drive sprocket and sprag bearings on the output. Basically like a Comet diff but with sprags instead of an actual differential gear.

 

[Functional Artist]

Thanks for the comments fellas
I'm NOT tryin' to "build a better mouse trap"
This idea is just a (potential) way to "easily" modify a kart, that already has a live axle
...& make it more user friendly

I understand that it would not transfer "as much" power as an actual keyed situation
...but, that's not the goal of this concept

The goal is to improve handling, without a lot of added costs, while reducing the "wear factor"
...thus, reducing damage to the axle or rim (extending it's usable life)

The kart could/would have the same axle, wheels, sprockets, bearings ...everything
...just have to add a spring & maybe some friction discs

 

[anderkart]

Check out these Ratchet & Free Roller hubs: http://www.mikeclementsracing.com/accessories.html

 

[Functional Artist]

Check out these Ratchet & Free Roller hubs: http://www.mikeclementsracing.com/accessories.html

Those are kool

While lookin' around/doin' research I came across a

Ball Differential
https://en.wikipedia.org/wiki/Ball_differential
...used on RC cars

& also these

Freewheel Posi Differential
https://www.utahtrikes.com/PROD-11619751.html
...used on bicycle type stuff

Still learnin' Thanks for the link, always lookin' for more info

 

[anickode]

Those are kool

While lookin' around/doin' research I came across a

Ball Differential
https://en.wikipedia.org/wiki/Ball_differential
...used on RC cars

& also these

Freewheel Posi Differential
https://www.utahtrikes.com/PROD-11619751.html
...used on bicycle type stuff

Still learnin' Thanks for the link, always lookin' for more info

That freewheel posi diff is exactly what I as talking about. Is uses one way/sprag/freewheel bearings to drive the output shafts. losing traction on one wheel doesn't cost you power at the other wheel but the outside wheel can still over run the inside wheel in a turn

 

[Functional Artist]

Been doin' more research on the different type/styles of Slip Clutches
(see examples of a few styles below)

I am interested in playin' with this concept a bit more
…& maybe doin' some testin' on a kart


I have a spring that may work
...but, what about "friction discs"?

Any advise on what kind of material to use as "friction discs")
...or where to get it?

 

[Bansil]

friction material

 

[Functional Artist]

Lookin' into friction material
Did ya ever notice that the more you learn, the more questions you have?
I learned that there is low friction, medium friction & high friction material, depending on the situation.

So, the first question arises, do we even need friction material between the spring & hub
...&/or between the spring & rim?

Second question
if so, what do we want this friction material to do?
...grip
… or slip

I was kinda thinkin' "both", we want this "Slip Clutch" to grip a bit, to provide traction during acceleration
...but, we want it to be able to slip, a bit, when necessary, like when turning

It seems to me that the "pressure" on the spring, between the rim & keyed hub should apply the "traction" (which is/should be easily adjustable)
…& the "give" of the spring should provide the "slippage"

The "friction discs" I had in mind (I guess) were more like some kinda washers (steel, brass, brake lining?)

Inexpensive/changeable parts, like a clutch disc or brakes pads
...mainly to protect the hub & rim, by "absorbing" the abuse from "the slipping"

 

[ezcome-ezgo]

Sector One 4-disc

I just tried the new disc out for air cooled 4-strokes and it’s awesome. I had been using the Bobs 4T but this stuff is really good. We had it on a dyno with my new LOL-206 and it made 16% more torque and 18% more HP. I ran into the guys that developed this disc at Pitt Race during the Rotax Challenge race and they gave me a couple to try out. They said it’s coming out towards the end of this month but their break-In disc is already available through eBay. I’m sold.

 

[Tpdingo]

I'd say the easiest way to make a diff into an LSD would be to attach the spider gears to a fin/turbine like shaft(ie the center pin that is already there) and fill the diff with some really thick grease or heavy weight oil. In normal turns as the final spin in the oil/grease, it will be slow enough to turn fine but if one wheel is spinning, that spider gear is going to spin up very quickly and in theory the heavy weight oil will act like a torque converter of sorts and transfer power into the other non moving axle. I figure that for a relatively light kart, this should do fine.