A revolution in suspensions ?

[setecastronomy]

It is more and more difficult to see something which is really new on today's crawlers. Besides the attention seems focused on other axles such as the Ax-10 and the revolutions (the SW3, the use of the brushless, the droop, the dig ecc.) belog to the past.

I tryed to realize a new type of suspensions.

The idea is to decouple the twist movement from the vertical one.
So I made a hub connected to the chassis with 4 equal lenght parallel links. Those links should allow only the vertical movement of the hub, but for the prototype I used the usual rod ends with balls adding some washer. In the Hub there is a hole for a pivot which is firmly connected to the servo plate of the axle, so the twist is around this pivot.


The servo plate is on the left


The hub mounted on my crawler, view from below

The hub mounted on my crawler, side view
An off-camber spot

The same spot from another angle

Obviously the system should be improved, but I wanted to open a new road with a prototype. The performances are not worse compared with the previous traditional 4-link suspension.
When I will have a clear idea of the weak points and pro and cons of this suspension I will extend it to the rear axle.

Bye
Filippo

Saluti
Filippo

[littleskull99]

forgive me having to ask but what are the advantages of this link mount?

[TattooKenny]

Won't the links stay in the way when it flexes? ( Meaning in the way of rocks and so forth...) And the shocks are connected to the axles so the flex won't be any greater than a normal 4 link? Am I missing something here?

[setecastronomy]

Originally Posted by littleskull99

forgive me having to ask but what are the advantages of this link mount?

It is hard to have advantages on a well tuned 4-link traditional suspsension but it is worth to try.

There is no need to triangulate the upper and lower llinks on a horizontal plane.
There is no roll steering.
It is extremely simple to undersand.
The axle twist exactly at the center of the pivot, which is a well know point and not in the imaginary point the theory of 4-link suspension says.
If you don't want the pinion angle to change during the suspension vertical movement you may have some difficulties with a traditional 4-link suspensions to make upper and lowers of equal lenght.

I admit no one of the above point is so important for excellent performances but in some circustances they can make the difference.

Bye
Filippo

[littleskull99]

So what stops your axle moving side to side? Is it the washers on the ballends?

Matt

[setecastronomy]

Originally Posted by littleskull99

So what stops your axle moving side to side? Is it the washers on the ballends?

Matt

At the moment I use the washers, but it is not the desirable solution. It is a temporary workaround. Besides I used Tlt rod ends and balls, whichdon't allow too much out of axis movement.

Bye
Filippo

N.B.
The twist movement is around the pivot which connects servo plate and hub. It is limited by shocks and by the slider connected to the pinon axle, but it is more than sufficient.

[littleskull99]

So you are using the driveshaft as a suspension limiter?

[setecastronomy]

Originally Posted by littleskull99

So you are using the driveshaft as a suspension limiter?

I hope not. Fortunately shocks reach their bottom before the hub touches the slider.

[littleskull99]

ah right, How does it perform?

[backtrailzracer]

its a good idea but it doesent seam like thats realy needed becuse with a standard 4 link you can get up to 90 deg of flex and just hve to say you need to shave the bottom of your axles that will make a huge improvement

[Defender]

Interesting! Looks like that set up should help with axle steer. Can you post some flex shots?

[setecastronomy]

Originally Posted by Defender

Interesting! Looks like that set up should help with axle steer. Can you post some flex shots?

Sorry, I think I will not post new photos soon because I would like to improve the system before.

Performances don't seem worse than those of a 4 link traditional suspension, but I didn't test it very much.

My design opens some new ways to investigation. Lower links can be placed higher on axle side for more clearance and shocks can be mounted in a different manner (lots of people have the problem they scrab against the turned tire in twisting). I think they could be connected to the hub and not to the axle, while a rubber band could set the steady position of the axle respect to the hub.

Bye
Filippo

[setecastronomy]

Finally I made a major upgrade to the suspension using new materials.

Common rod ends with washer to limit their lateral movement were replaced by pivot (on the right near the servo plate) derived from furniture hardware. Rod ends were made cutting and drilling a plastic plate. The axle pivot was realized using bronze and a lathe. A new hub is visible on top while on the left their is a plate for mounting the esc and connecting together the upper links in order to make them stiffer and avoid any twist of the hub.


The front suspension (those Msr10 are huge )

Front supsension from behind

Rear supension with a little axle twist (notice the iron block on the servo plate where the bronze pivot is connected)

Rear suspension

Side view

Repositioning the links on the hub now I have much more clearance but the shaft is completely exposed to rocks. If it wears or breaks I will change it with a metal one. In the front I would like to remove the shocks and put a torsion bar which keeps the axle horizontal, but I have no experience with torsion bars. I made some tests placing the shocks between the hub and the chassis. That way they acted only on the vertical movement of the axle while the twist was completely free. Unfortunately such a setup is obviously affected by a teriible torque twists.

Bye
Filippo

[Nitro_Geezer_UK]

looks good......but i really cant see the advantages/dis-advantage or the point of it all

Good for thinking outside the box though

[setecastronomy]

Originally Posted by Nitro_Geezer_UK

looks good......but i really cant see the advantages/dis-advantage or the point of it all

Good for thinking outside the box though

The lower links are much higher than in other crawler, so I can run lower.
The idea behind this project is to completely decouple the twist from the vertical movement of the hub. Unfotunately due the way shocks are mounted thsi goal is not achieved yet. I don't even know if it is desiderable.

Bye
Filippo

[theslowguy]

From what i can see the links stay stationary but can still travel up and down and the suspension flex comes from the pivot. and is limited by the shocks. Simply you extended the chassis out to the axles and replaced the the job the normal 4 links do with the pivot. I like it.

[tanmonster]

I think it is awesome! It seems that it would perform like a tlt version of a stick chassis. Try adding two triangulated upper links to help prevent side to side movement.

[ROCKEDUP RICKY]

How about mounting shocks on the inside of the chassis and to the top of the pivot. They would be shorter than what you got right now.

[Krawler Freak]

i like the idea good out of the box thinking mate!

[tom tom]

To me it would seem that having all four links parallel would not work very well. I think that if you have the top and bottom links facing inwards, but at different angles. that would eliminate heavy bracing. I do like your concept. Its making a stick level comp out of a four bar chassis car.