Electric active rollcentres

[Apricot Slice]

invented this around about the same time as Dax.
A little different as you can see. with the use of a Watts linkage.

http://i471.photobucket.com/albums/r...IMG_0884-1.jpg

http://i471.photobucket.com/albums/r...8/IMG_0885.jpg

http://i471.photobucket.com/albums/r...8/IMG_0886.jpg

[mark christopher]

Originally Posted by terry.sc

The Tekin chassis was also the first race buggy mid motor conversion as well - over 20 years ago. It shows just about everything was tried years ago.

The Tekin system is different to the Serpent one. The Tekin has both upper links attached to a single sliding mount so as the suspension moves straight up and down it has no effect on the upper links, while the Serpent design will move the wheels in and out. The Tekin design has less effect when wheels go over bumps, but will still pull the wheels upright when cornering.

INcorrect, as i have posted when the chassis goes up and down the wheels do NOT alter thier angles (providing both arms are moving)

http://www.youtube.com/watch?v=h73MC40VPsU

http://www.youtube.com/watch?v=11xXhxjZQeA


hard to explain but when you have seen/used it in action its simple

[terry.sc]

Originally Posted by mark christopher

INcorrect, as i have posted when the chassis goes up and down the wheels do NOT alter thier angles (providing both arms are moving)

..which is different to a standard suspension setup where the wheels will lean in due to the fixed upper link attachment. The Tekin system replicates a normal suspension under straight compression. The Serpent system moves both upper link attachment points outwards as the suspension rises which if it is adjusted right can keep the wheels vertical, but it isn't the same as what happens on a normal suspension.

I would like to see you demonstrate the Serpent system keeping the wheels vertical over the sort of wheel travel a buggy has, not just the rather short travel of a nitro on road chassis.

Can I also point out that the first video link you posted demonstrates the chassis in roll, but never actually moved the chassis vertically to back up your argument.

[neallewis]

Originally Posted by terry.sc

The Tekin chassis was also the first race buggy mid motor conversion as well - over 20 years ago. It shows just about everything was tried years ago.

I spotted one here tonight.

[Rebelrc]

This is the Dax system
http://www.daxcars.co.uk/start.htm

[mark christopher]

Originally Posted by terry.sc

..which is different to a standard suspension setup where the wheels will lean in due to the fixed upper link attachment. The Tekin system replicates a normal suspension under straight compression. The Serpent system moves both upper link attachment points outwards as the suspension rises which if it is adjusted right can keep the wheels vertical, but it isn't the same as what happens on a normal suspension.

I would like to see you demonstrate the Serpent system keeping the wheels vertical over the sort of wheel travel a buggy has, not just the rather short travel of a nitro on road chassis.

Can I also point out that the first video link you posted demonstrates the chassis in roll, but never actually moved the chassis vertically to back up your argument.

And the way a Wheel leans in is due to a compromise for corner grip on linkages
My other vids do show up and down

[sparky-0]

Heres my system fitted on to a Losi 22. The rear shock tower pivots in the center and is driven by the servo which is on a Y lead with the steering. As the steering turns right the left shock is compressed and the right shock is lifted , and vise versa for steering left, taking out the chassis roll. It works very well, it may not conform to brca rules but at club racing it does'nt matter

[coleman758]

That's pretty cool, I'd love to see that concept in action!

[Groomi]

Originally Posted by sparky-0

Heres my system fitted on to a Losi 22. The rear shock tower pivots in the center and is driven by the servo which is on a Y lead with the steering. As the steering turns right the left shock is compressed and the right shock is lifted , and vise versa for steering left, taking out the chassis roll. It works very well, it may not conform to brca rules but at club racing it does'nt matter

Interesting execution of that idea. How does it deal with heavy offset landings?

Also, would it conform to BRCA rules if it didn't use a dedicated servo (ie. if somehow driven by steering servo), or is it simply a case of powered as opposed to mechanical not being allowed?

[mark christopher]

Originally Posted by sparky-0

Heres my system fitted on to a Losi 22. The rear shock tower pivots in the center and is driven by the servo which is on a Y lead with the steering. As the steering turns right the left shock is compressed and the right shock is lifted , and vise versa for steering left, taking out the chassis roll. It works very well, it may not conform to brca rules but at club racing it does'nt matter

dont we rely on chassis roll to load the outer front wheel for steering?

[Apricot Slice]

looks like its ok in the rules. (the variable camber ones)
As far as 'is it any good on track' goes, I be interested to know.
It has obvious advantages for on road.
For off road i guess the biggest thing would be having more suspension travel on the outside cornering wheels because the lack of roll. Wether its an advantage overall I have no idea. Would be interesting to hear what the experts have to say.

The impression I got when I made my little prototype 20 years ago was that it would be very difficult to make ajustments. Every little change has so many effects. Just figuring out what the roll centers are doing boggeles the mind.

[mark christopher]

think im right in saying the serpent one does not rely on roll centres as the wheel is allways at the set camber and tyre is flat on the track

[Origineelreclamebord]

Originally Posted by sparky-0

Heres my system fitted on to a Losi 22. The rear shock tower pivots in the center and is driven by the servo which is on a Y lead with the steering. As the steering turns right the left shock is compressed and the right shock is lifted , and vise versa for steering left, taking out the chassis roll. It works very well, it may not conform to brca rules but at club racing it does'nt matter

Interesting, I've been thinking of doing something like this for a month or so now... Great to see it actually works then!

Just wondering though, what happens if you make the system such that it rolls into a corner (like a motorcycle) instead of just staying level?

[dodgydiy]

surely it would be better to move a mass inside the car such as the battery towards the inside of the corner to stop it lifting than to alter the suspension at one end of the car only. it worked on an old rc10, so surely it would work on a modern car given enough space inside the car to allow a pivoting tray to be fitted

[baw888]

The real effect of the serpent and tekin designs is a live real axle. Exactly the same movements. Only benefit is you could build a set up somewhere half way. Might be better for on road but off road a system that lets the car roll in the corners for grip, then stabilizes the car on the straight might work better?

[jo90]

If I read it right, and only to confirm with those above, as long as the system is passive (ie not controlled by remote connection or force) then it is ok to use. Passive in motor sport generaly meens something acting on something else by meens of a natural force...not mechanicaly driven or forced by motor or similar acting unit.

The LRP unit back at the worlds all them years ago was a classic 'non-Passive' unit. As mentioned the giro and ESC along with a sensor on the front wheel (i believe it was the front) was used to see if the car was tailing out or spinning the wheels up. It then reduced RPM to steady the car. You can imagine the uproar it caused, though I dont believe it won the event (it may have been banned during the event if i recall).

So, in short yep the push rod system as seen on that serpent car would be legal, as would other push rod systems being passive.

[jo90]

Originally Posted by sparky-0

Heres my system fitted on to a Losi 22. The rear shock tower pivots in the center and is driven by the servo which is on a Y lead with the steering. As the steering turns right the left shock is compressed and the right shock is lifted , and vise versa for steering left, taking out the chassis roll. It works very well, it may not conform to brca rules but at club racing it does'nt matter

Really neat and good idea , but BRCA illegal

Top work though, it looks bloody good

[Sheepdog]

Originally Posted by sparky-0

Heres my system fitted on to a Losi 22. The rear shock tower pivots in the center and is driven by the servo which is on a Y lead with the steering. As the steering turns right the left shock is compressed and the right shock is lifted , and vise versa for steering left, taking out the chassis roll. It works very well, it may not conform to brca rules but at club racing it does'nt matter

just out of curiosity, if you were to do away with the servo and just had the shock tower pivoting would that not have a similar natural effect, might be the cider talking but just a thought