78 replies to this topic

[kikiturbo2]

I have offered my twin sprag clutch LSD idea many a time. Spool drives left and right sprag clutches, clutches drive axles, turn corner outside wheel is free to go faster.

that will give you corner entry understeer....

[MatsNorway]

I have offered my twin sprag clutch LSD idea many a time. Spool drives left and right sprag clutches, clutches drive axles, turn corner outside wheel is free to go faster.

Have i seen it?

Whats the beavior from a locker under braking or off throttle? just freewheeling? i can`t have that.. a balldiff or oil diff(gear diff) is very tunable. The main reason i want a spool function going forward is because when you tune a simple balldiff you must consider both acc and braking.


With the spool forward your now only adjusting braking when you tune the diff.

Most full scale diffs are to complicated to replicate in 1/10scale
http://image.off-roa...ifferential.jpg

GreenMachine
Thank you, good enough then.

Edited by MatsNorway, 15 February 2012 - 15:27.

[Wolf]

And what is a locker?

Yeah, it sounds similar, although Locker can engage or disengage under power, and that was it's biggest shortcoming. My proposal is spool under power and 'no diff' when braking... Speaking of spools, do I correctly remember that Porsches 917 up to 962 used spools?

Kikiturbo, I think all LSD action is contribution to understeer... Although I would think that it's raison d'etre is power-on understeer (and I can see Cheapracer's design providing for it, although I would think that a choice of type of clutch would be instrumental for a way it would affect handling).

[cheapracer]

Speaking of spools, do I correctly remember that Porsches 917 up to 962 used spools?

Yup, lots of Porsche race cars used no diff at all from Mark Donahue onwards.

Edited by cheapracer, 15 February 2012 - 16:00.

[Wolf]

Cheapracer, did you mean that I should share the 3D model in question? What's next- you'd want me to upload and let people use (free of charge, I presume) various suspension components I've modeled, like proper suspension springs that allow suspension CAD model to be moved, or models of spherical bearings and rod ends where one only needs to select the product from a catalog, or even whole shock absorber 'mockups'???

OK, you win- My GrabCAD profile...;)

[MatsNorway]

Nice, gonna have a look at that diff at work if i get the time. See if i can get some ideas from it.

The reason i need diff action during braking is because RC cars brake with the drivetrain. moi moi important.

Edited by MatsNorway, 15 February 2012 - 19:41.

[Wolf]

Mats, how about trying (failed*, I should add, but nevertheless interesting) B.R.M. idea of a single brake braking through the diff (IIRC they were used on that gorgeous Type 25 and latter P48)...

* ISTR that the problem was cooling. the brake which was fully enclosed by the bodywork

[MatsNorway]

Could be something for the Nitro cars. The the electric ones are only allowed to have one servo. For steering. I have been pondering about dynamic diff with input from steering servo.

I have a paper sketch in my drawer at work. just need to get the energy to make that one after work.

I am allowed to install the software at my home pc so within a short time i will have it home too.

work work work.

Edited by MatsNorway, 15 February 2012 - 21:34.

[24gerrard]

Mats, how about trying (failed*, I should add, but nevertheless interesting) B.R.M. idea of a single brake braking through the diff (IIRC they were used on that gorgeous Type 25 and latter P48)...

* ISTR that the problem was cooling. the brake which was fully enclosed by the bodywork

Alec Stokes designed it, it was called the cheese grater.

[Wolf]

Could be something for the Nitro cars. The the electric ones are only allowed to have one servo. For steering. I have been pondering about dynamic diff with input from steering servo.

I have a paper sketch in my drawer at work. just need to get the energy to make that one after work.

I am allowed to install the software at my home pc so within a short time i will have it home too.

work work work.

Mats, if you're up to fiddling a bit, I'm sure additional braking could be done without servos... Off top of my head, I remember brakes that used permanent magnets acting on simple discs- conversely, you could have electromagnets instead that would get the current when 'throttle' is closed.

[gruntguru]

I have offered my twin sprag clutch LSD idea many a time. Spool drives left and right sprag clutches, clutches drive axles, turn corner outside wheel is free to go faster.

. . . and I like it every time you offer Cheapy.

No engine braking though, fine for race cars but not so good for road cars.

[kikiturbo2]

Mats, if you're up to fiddling a bit, I'm sure additional braking could be done without servos... Off top of my head, I remember brakes that used permanent magnets acting on simple discs- conversely, you could have electromagnets instead that would get the current when 'throttle' is closed.

hmm, talking about 1/10 scale electric cars.. how about a small diff filled with fluid that WV uses in dampers, whose viscosity is varied by magnetic field.. could have a active diff with not a lot of parts..

On a similar note.. I really like the natural feel of torsen, and adjustability and "bite" of a plate diff.. but after having sampled active diffs of two kinds... there is just no going back.. (says he and goes back to fixing a hydraulic diff pump... )

[24gerrard]

hmm, talking about 1/10 scale electric cars.. how about a small diff filled with fluid that WV uses in dampers, whose viscosity is varied by magnetic field.. could have a active diff with not a lot of parts..

On a similar note.. I really like the natural feel of torsen, and adjustability and "bite" of a plate diff.. but after having sampled active diffs of two kinds... there is just no going back.. (says he and goes back to fixing a hydraulic diff pump... )

Discussed the magnetic fluid idea with Tony Rudd at Lotus decades ago, he had a thing about it.
Even built some automatic transmission clutch drums using it with coils.
We considered a complete transmission system based on it.
Worked fine, cost was the problem for general use plus little gain in packaging or efficiency and difficulty in sealing etc,
of course for F1 the damn regulations again.
Dampers were the logical application for the fluid system.

The twin hydraulic pump slipper diff can also be a dual path CVT transmission of course.
If Williams had been allowed to use their Van Doorne CVT that Coulthard tested before it was banned,
no doubt we could have entered that hydraulic diff/CVT in F1, yet another development stopped dead.

[cheapracer]

. . . and I like it every time you offer Cheapy.

No engine braking though, fine for race cars but not so good for road cars.

Well you could have it solo for a race car and piggyback it on an open diff for a road car.

Cheapracer, did you mean that I should share the 3D model in question?

No, I meant a 3D animated Cam and Pawl so everyone can finally understand how they work.

[cheapracer]

Oh and welcome back Grunt.

Now about that torque Vs power issue , I reckon that ......

[gruntguru]

Oh and welcome back Grunt.

Now about that torque Vs power issue , I reckon that I was wrong and you were right.

Thanks Cheapy - and very gracious of you too!

[24gerrard]

Cheapy has been realy nice lately Grunt.
Confucius say 'send another carton'.

His sprag clutch diff would work OK I think.
The trouble with all pawl and roller locker diffs is the jerk they always seem to have when asked to apply the lock in high torque use.
I used to dread this when I dropped an outside wheel onto a loose surface when racing my 150 bhp Mini fitted with a Jack Knight roller lock diff. It would often throw the car off the road.
Cheapies sprag system would probably be less fierce.

[Wolf]

No, I meant a 3D animated Cam and Pawl so everyone can finally understand how they work.

Will do if I ever get to grips with it myself... But what really pisses me off is that I'm currently using 2 state of the art CAD systems, and will probably have to call upon services of dedicated engineering math package to come to terms with a bleeping contraption that was invented and designed almost 80 bleeping years ago by a few guys in lab coats using nothing more than bleeping slide rulers!! (oh, how I wish I had the disinterest in such things that I've encountered while being involved at my Uni)

[cheapracer]

Thanks Cheapy - and very gracious of you too!

I have to be nice to 2 people a week for my therapy.

One more this week then back to normal ....

[24gerrard]

I have to be nice to 2 people a week for my therapy.

One more this week then back to normal ....

http://player.vimeo....5908?autoplay=1

Working on a new diff for drifting.
If it works out every drifter will have one.
After all they need something to do at 50 mph and it should keep the hands busy.
In this test the strain blows his rear end but he is working at it.

Edited by 24gerrard, 16 February 2012 - 18:00.

[Lee Nicolle]

Cheapy has been realy nice lately Grunt.
Confucius say 'send another carton'.

His sprag clutch diff would work OK I think.
The trouble with all pawl and roller locker diffs is the jerk they always seem to have when asked to apply the lock in high torque use.
I used to dread this when I dropped an outside wheel onto a loose surface when racing my 150 bhp Mini fitted with a Jack Knight roller lock diff. It would often throw the car off the road.
Cheapies sprag system would probably be less fierce.

On a front drive car anything more 'sophisticated' than a simple LSD is an accident waiting to happen. I have seen Minis take themselves off the track big time with LSD troubles, good rubber on bigger rims accentuates this even more.
Having raced against a 300hp 13B mini was very exciting as the drivers input was sometimes coincidental as to where the car went,,, that was in a straight line yet alone corners!

[munks]

http://player.vimeo....5908?autoplay=1

Note: we younguns with corporate jobs like things labeled "NSFW".

But, yeah, it looks like she's running a little loose there.

Edited by munks, 17 February 2012 - 14:43.

[Tony Matthews]

Needs some digital restraint from behind.

[GreenMachine]

Should be in the packaging thread ... ?

[24gerrard]

Should be in the packaging thread ... ?

Na, weight distribution and fluid dynamics.
I have a handle on that.

[gruntguru]

Na, weight distribution and fluid dynamics.
I have a handle on that.

Fixed.

[MatsNorway]

I had a look at it at work. good model. some shapes seems a bit uneasy to make but well made.

Its Surpricingly simple component, rather brutal actually . I did also download a LSD and that had tons of pieces.

Edited by MatsNorway, 20 February 2012 - 08:48.

[Wolf]

Glad you liked it Mats. (and a good thing to hear after I've wasted a day yesterday trying to do some 'styling' work on my car model... just couldn't make the damn thing look remotely good maebe I should concentrate on the proper design, but I thought I give a surface modeling a go, and didn't particularly enjoy it)

[MatsNorway]

Machine component design tools are crap for designing smooth shapes and such. at least inventor. I think Maya and 3DS max is better for that. But im not sure about it. Dunno about Catia but i know some of the F1 teams use it.

When i said some shapes looked uneasy to make i meant uneasy to reproduce in real life.

Edited by MatsNorway, 21 February 2012 - 15:58.