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One way bearing/clutch and overdrive


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#1 MatsNorway

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Posted 23 January 2012 - 18:38

In relation to this thread http://forums.autosp...howtopic=159765
and the discussion about the Palatov D4

Im wondering if anyone got some experience with one way bearings or one way clutches? What sort of power levels are they able to take?

And is it any spesial designs out there?

I was thinking a one way clutch/bearing device that could be run together with a slight rear overdrive on the Palatov D4. Say you run the CHAIN... 4WD system and run say 29 teeth on the center diff and 30 on the front diff.

That would mean that you need a minimum of 2.5% wheelspinn at the back compared to the front. Before the front connects. It was my first thought to fix a understeering and simplisticly designed chain driven car.

http://www.lowellcor...aysprocket.html

Some comments about the Palatov D4 and that Chaindrive 4WD in relation to this is desired.

Edited by MatsNorway, 23 January 2012 - 18:42.


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#2 TC3000

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Posted 23 January 2012 - 19:37

maybe you find some answers here and here

Edited by TC3000, 23 January 2012 - 19:40.


#3 Greg Locock

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Posted 23 January 2012 - 21:09

Good quality one way bearings are used as anti rollback bearings on long uphill conveyor belts. The principle is the same as a bicycle freewheel, but they are obviously far more rugged.



#4 cheapracer

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Posted 24 January 2012 - 05:12

This was my solution to another guy building a budget chain drive AWD ..

Posted Image

Look at the drawing, somewhere up front have a simple teeth ratchet mechanism with angled one way teeth and a side thrust spring. Over that length of chain 10mm side to side movement is nothing to engage/disengage the teeth. Your front drive dogs free spin on a shaft and the rear drive dogs while turning slower simply ramp over the other dogs ramps but when they get faster (wheelspin) they meet each others 90 degree dog faces. Also allows handbrake of course!

The front drive final ratio would be about 5% taller than the rear final ratio.

#5 MatsNorway

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Posted 24 January 2012 - 18:22

It would last a race i guess.. and do the job. but in time and machining work it would come close to just buying the a mass produced unit mentioned above don`t you think? And it would be a fair bit less smooth and predictable in the gray areas.

A quick glance at the tables in the links from TC3000 and it shows that they would get a bit heavier than a normal diff i would think.

Type 2020 line dash dash dash line 020 series.. weights in at 8.2kg and can take a max load of 3500Nm. it sounds good enough. Possibly on the heavy side. IF a issue you could complicate things a tiny bit and use it before the final gearing have taken place to make the driveline take more abuse.

But what about the overdrive idea?

having the rear to overdrive with say 2.5% to get a more RWD like behavior.

Edited by MatsNorway, 24 January 2012 - 18:25.


#6 bigleagueslider

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Posted 25 January 2012 - 05:30

MatsNorway,

The most durable and compact type of freewheel/clutch device is probably the sprag clutch, and they are produced by FormSprag. Sprag clutches are commonly used in automatic transmissions. When engaged, sprag clutches are torque limited. And this torque limit is primarily a function of the hertzian contact stress produced between the sprag elements and the inner/outer race surfaces. When overrunning, sprag clutches are limited by their PV (Pressure-Velocity) coefficient present at the sprag/race sliding interface.

http://www.formsprag...strialframe.htm

slider


#7 cheapracer

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Posted 25 January 2012 - 06:32

It would last a race i guess..

But what about the overdrive idea?

having the rear to overdrive with say 2.5% to get a more RWD like behavior.


The system is simple, rugged in design and totally up to the maker of how large he makes it and it's not hard at all to make. What's annoying me is I have seen these very things and I can't remember where...

The rear is underdriven not overdriven and more likely 5% that has been shown in 2WD motorcycle testing.

Sprag clutches are fine but a lot more work involved in fitting/adapting/sealing. Sprag clutches are made by many all over the world and come in a variety of clutch designs for different purposes, mate of mine used to service mining companies conveyor belts that uses them to stop belt reversal on slopes.

Helicopters use them so if the engine seizes the blades keep spinning for autogyro apparently.


#8 MatsNorway

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Posted 25 January 2012 - 10:13

The system is simple, rugged in design and totally up to the maker of how large he makes it and it's not hard at all to make. What's annoying me is I have seen these very things and I can't remember where...

The rear is underdriven not overdriven and more likely 5% that has been shown in 2WD motorcycle testing.



If the the rear wheels goes faster surely thats overdrive?

But most important what would it handle like with a oneway system and more drive on the rear?

I think 5% would be more than normal on a car. i heard the numbers where the traction systems limited it to 7% (ferrari?) and merc used somewhere around 5%. Most where around there. ofc these days the sportiest cars got it adjustable.



#9 cheapracer

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Posted 25 January 2012 - 12:06

If the the rear wheels goes faster surely thats overdrive?


Unless wheel'spinning, the wheels turn the same speed, it's the drives that vary in speed.

I forever get confused with the various ratio terminologies, if you had a rear diff ratio of 3.9 then the front would be 4.1 for the 5% split - you call it.

Oh, btw, unless you have a release system you can not reverse very easily as the engine has to overcome the bind, you most certainly will not be able to push the car backwards. With my system a simple throwout fork would bypass the issue.

Edited by cheapracer, 25 January 2012 - 14:13.


#10 MatsNorway

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Posted 25 January 2012 - 16:26

Unless wheel'spinning, the wheels turn the same speed, it's the drives that vary in speed.

I forever get confused with the various ratio terminologies, if you had a rear diff ratio of 3.9 then the front would be 4.1 for the 5% split - you call it.

Oh, btw, unless you have a release system you can not reverse very easily as the engine has to overcome the bind, you most certainly will not be able to push the car backwards. With my system a simple throwout fork would bypass the issue.


****... now i get what you mean.. the front has to stay faster so that it will only engage once the rear starts spinning faster than it. the front needs to have "overdrive" (overroll...hihi..)

looking back it seems that i got the gearing wrong.. you want higher speed on the one way bearing so that it only connects when the rear wheels spinn beond the ratio determined by the gearing:
meaning it shall have 39 teeths vs 40 on the front diff.

Edited by MatsNorway, 25 January 2012 - 16:27.