The relative benefits of a pull rod suspension

[ringo]

But we're seeing the slight benefits here aren't we?

Actually in case of the Tyrrel I see that the exhaust is very close to important suspension parts. Something I don't see as benefit.

The exhaust gasses aren't blowing on it. Unlike the current ebd, he pipe is closed and only exits under the car. No heating issue there at all. Also would be no different to a push rod in this case.

I also don't like the flat angle the pullrod has it increases the forces in the suspension members.

It's the perspective of the shot giving the impression the angle is flat, but anyhow the joint forces would be the same regardless of angle. The arms are designed to take the force, so that's not an issue either.

I like to have the wishbones mounted as low as possible.
Reasons to stick with pushrods.

I rather have the paper light upper wishbones as high as needed if it means putting something way heavier lower.

However I don't think it make a big difference if you have pull or pushrod. RedBull got its big advantage from its aero.

And redbull's aero efficiency is a result of the tight shape of the rear end afforded to it by the pull rod system.
The pull rod is mechanically the same as the push, but it's benefits lie outside of the suspension itself.

[Jersey Tom]

[PlatinumZealot]

I have an "e" magzine for you guys:

http://issuu.com/racecargraphic/docs/rt ... phenomenon

It is about the pull-rod suspension.

[Giblet]

The pull/push argument follows closely with the keel arguments from a few years ago. Yeah, everyone was all excited about the zero keel configuration and and tripping over themselves to have it, yet here was Ferrari, still winning races and championships with the single keel.

[PlatinumZealot]

So the zero keel was the flavour of the week then? Who won with it to cause that? ( pardon me, i'm no F1 history buff)

With the zero keel maybe Ferrari were the exception to the expected tendencies? We could easily expect that the pull-rod and redbull nose are going to be the next trends. Who will be dominant adopting it or who will be dominant ignoring it is what is the question.

what I found interesting in the article is the fact that during the first ground effect era everyone used rocker arms. Then after that first era died Mclaren dominated with the push-rod equipped Mp4-2 wining 12 out of 16 races of the 1984 season. EVERYBODY and his cousin had to have a Pull-rod suspension on his car then! And the pull-rod suspension dominated for the next 25 years... Isn't it ironic?


Also notice that the influence of the mp4-2's pull rod may have stalled widespread development of what may be the more superior pull-rod suspension. It Further bolsters my notion that the decades of non development has been regained by high speed computing and this has enabled Newey to bring the pull rod up to the level where it is at today.

[marcush.]

sorry to be nitpicky here...
but as far as I understand the single keel high nose was challenged by the twin keel hype...I think this was a Postlethwaite idea realised first time on the Honda development car (by Dallara)..leading to Arrows and Mclaren twin keel extremes.
Renault had something called V keel ..

Toyota came back to No-keel layout and angled downwards wishbones that are now the must have....with Newey followers now in between single keel and no keel
and notably Mercedes W01 coming back to something akin even more to a Monokeel.

the no keel approach opens the possibility of lowering the steering rack to lower wishbone level at the expense of a bit more divergence between monocoque and front tyre.(the forrest of rods between tub and Tyre due to steering rack below the upper wishbone we see on the newey type solution has add to blockage as well ).

[ringo]

Hear ye Hear ye!!

I present to you fashion statement of the 2011 season. The Pull rod suspension is in!!

Rumors speak of a Ferrari revolutionized aerodynamically and is ready to use two technical solutions already adopted successfully by Red Bull:

- A high nose, wide and flat, "hollowed out" in the lower

- Pull-rod suspension at the rear

Despite all the complications related to the use of KERS, Ferrari realized that the road to success passes mainly aerodynamic efficiency.

Because the muzzle-style Red Bull?

One of the main aims at the technical level for the 2011 season is to recover the lost downforce at the rear after the disappearance of the diffuser.

It 'also need to rebalance the entire car because the static weight distribution has been fixed by regulation. In the front, the current F1 and load have too compared to what you can get behind. For this reason, in recent months in the wind tunnel, we have studied a solution with a high nose and flattened as the cars designed by Newey. As we know, the 2011 technical regulations, has established a limit on the elevation of the "nose" than the level of the passenger to try to avoid penalizing the visibility. High nose, it means a pretty carved and arched frame at the bottom, so as to leave as much space as possible below, in order to allow a greater flow of air to the rear. This will help the speaker to work in the best way retrieving cargo at the rear.

Because the pull-rod suspension?

Ferrari last year had already seen a return to the pull-rod suspension, or rod for the F10. That solution was then discarded from complications due to the presence of the diffuser.

What is the difference between pull and push-rod-rod?

In the first, the spring-damper is located at the bottom, and the movements of the wheels are absorbed by a rod that works in traction, lashed down to the gearbox and at the top of the wheel.
In the push-rod, the group is up and absorbing the vibrations are transmitted by a strut, a rod that is pushed by the wheel, from bottom to top.

With the disappearance of the double diffuser, is forced to come back with extractors and low volumes have to be used differently in space. For this reason, the pull-rod solution becomes convenient as it allows to bring the weights down, helping to balance the car, goes well with a discharge in a lowered position, giving less heat problems.

If the winning car has it, copy it with no second thoughts. Don't think about it just copy it, you wont regret it.

The same exact reasons i gave are here. No DDD, that's why most teams didn't use the advantageous pull rod last year.

[JohnsonsEvilTwin]

My prediction is coming on a treat!

[myurr]

If the winning car has it, copy it with no second thoughts. Don't think about it just copy it, you wont regret it.

That's such a ridiculously stupid statement...

For example: last years winning car had a Renault engine and a really young driver. Should all teams just copy that?

Pull rod suspension has advantages and disadvantages. If the advantages work with your overall solution then great, use it. But it's not some magic bullet and if one of the top teams finds a better solution, rather than just blindly copying, and it works then we could easily see a push rod car winning the championship.

I agree that with the current aero trends the pull rod probably makes enough sense that we'll see all the top teams go down that route. But equally I'll not be worried about any team that chooses a different route - it won't automatically mean their car is going to suck.

[Ciro Pabón]

I think pull rods are used more, at least in constructor formulas, like FSAE.

People says that:

Dampers are lower, below driver knees, so, you could get a better packaging and lower CG.
Load paths are more or less the same, compared with pushrods
Design is slightly efficient, no buckling in compression (where the load peaks happen) nor you need the asocciated material put in place to avoid delamination.

On the other hand, you have less suspension travel and anyway you have buckling in droop.

Just in case, here is the difference, for the less tech savvy.

Pull rod (when there is a bump, you pull the rockers that move the dampers. Notice the dampers are in a lower position, compared with the following image)


Push rod (you push the rockers)


Usually, the arms are slightly shorter in the pull rod type, so less drag (I wonder if that's noticeable)

In civil engineering is a mortal sin to use a bar in compression, btw. Bars are made to be pulled the same way axles have to be hollowed. In the first case the bar will buckle (so you have to make it larger to be less slender so it won't buckle) and in the second case the material at the center of the axle contributes little to torsional resistance. So, most civil engineering structures in compression or torsion tend to be hollow columns.

However, I've never got the hack of mechanical structures and I guess there are a hundred reasons for secondary effects that cancel the disadvantages of push rods. If someone is so kind as to explain them to me in english (or spanish) I would be very grateful.

I agree with myrr: it's hard to automatically suck, but let's say it is easy... I do it all the time.

[Steven]

Cheeky bast***

Has anyone noticed the similarities with my drawing in the suspension article?
http://www.f1technical.net/articles/39

[ringo]

If the winning car has it, copy it with no second thoughts. Don't think about it just copy it, you wont regret it.

That's such a ridiculously stupid statement...

For example: last years winning car had a Renault engine and a really young driver. Should all teams just copy that?

Pull rod suspension has advantages and disadvantages. If the advantages work with your overall solution then great, use it. But it's not some magic bullet and if one of the top teams finds a better solution, rather than just blindly copying, and it works then we could easily see a push rod car winning the championship.

I agree that with the current aero trends the pull rod probably makes enough sense that we'll see all the top teams go down that route. But equally I'll not be worried about any team that chooses a different route - it won't automatically mean their car is going to suck.

I wouldn't copy the renault engine. Horner was very vocal about it. In fact he wanted the winning engines in the Mp4 23 and the Brawn, which in itself is an example of copying the winners.

As i said it's not a magic bullet, but if you don't have it and the other teams do, and they are enjoying the benefits, then you are behind.

I don't know of the performance disadvantages. There are ergonomic disadvantages to servicing or adjusting the suspension yes, but outside of that the push rod doesn't have an edge.

A push rod can still win the championship, but it will have to compensate for it's disadvantage to the pullrod in other areas. There is no reason to add this extra effort to prove a point with a lesser layout, it's better to copy what wins and save time and money for other areas of development.

Things don't always have to be fair and balanced. It's sounds nice and strategic when something has a weakness that hampers it's advantage over another thing, but in practice there are things that are simply superior for the application.

I am yet to see any performance disadvantages of pull rod to push rod. It is clear as day and has been repeated countless times why 1 is superior.

One other issue of the push rod is the thickening of the gear casing at the rocker mount locations. This puts more metal up high on the gearbox.
The pull rod keeps the stronger thicker walls of the gear box nearer the ground. This way the upper part of the casing can be lighter.
Ferrari mentioned cooling advantages as well. And with KERS this year, emphasizing weight, COG and cooling, the more you think about it the push rod would leave a team on the back foot.

[mep]

I am yet to see any performance disadvantages of pull rod to push rod. It is clear as day and has been repeated countless times why 1 is superior

Well when you think it is so superior can you explain why all teams used pushrods for so long time?

I think pull rods are used more, at least in constructor formulas, like FSAE.

Especially on front suspension this is true. There you get the advantage of low CoG. Aero is not important so apparently pullrod should be better but there are also drawbacks because the dampers can touch the ground and are generally more difficult to reach.

On the rear I would rate a pushrod slightly higher.
The problem is you simply have very little space there (chaindrive, differential, motor).

I guess they have similar problems on a F1 car. With the only difference that it is the diffusor that takes all the space. When you want to mount the dampers low you might take space of the diffusor (especially the side diffusors).
I guess the recent rule changes regarding diffusor brought the pullrod back.
The diffusors went bigger to the sides so RedBull found some space in the middle to mount dampers, rockers...

People says that:

Dampers are lower, below driver knees, so, you could get a better packaging and lower CG.
Load paths are more or less the same, compared with pushrods
Design is slightly efficient, no buckling in compression (where the load peaks happen) nor you need the asocciated material put in place to avoid delamination.

On the other hand, you have less suspension travel and anyway you have buckling in droop.

Less suspension travel???
That's new for me, can you explain closer what you mean?

[myurr]

One disadvantage is definitely packaging - the current cars are longer than last years so there is potentially more room to accommodate the dampers et al at the base of the car. Perhaps one of the teams will aim for a shorter car and wheel base and not have room for the pull rod configuration. The pull rod is not a new concept and many of the teams have run it in the past - they will have had their reasons for sticking with the push rod. Last year it was the DDD, previously it was for packaging, this year they may run it, next year they may go with a shorter wheelbase and have the same packaging issues as in previous years.

The point is it is not as clear cut as you often make out, and whilst it is likely there is no guarantee that it will be a car with a pull rod suspension that wins the 2011 world championship.

[Ciro Pabón]

Less suspension travel???
That's new for me, can you explain closer what you mean?

Well, what I mean is that the a-arms angle is shallower. It seems clear to me that for the same amount of vertical movement, the rotation the arms go through is smaller, got it? Also, the amount of camber change is smaller too (we discussed elsewhere how camber change in droop or bump influences grip).

For example, to get the same damper displacement for a given vertical displacement of your wheels, you have to build longer rockers. Am I wrong? Please, retro-feed, mech-guys. thanks.

Tomba, I got the drawings from another site, just check the images URLs, I haven't read your article, don't call me names, please or I'll complain to mods and you know how hard is Principessa with some guys. I resent that: I am a bastard but I'm not ch%$eky. Besides, the drawings are totally different... you can see that your signature is absent. Duh.

Apart from that, I conccur with you: I cannot imagine why site admins don't police the copyright of the images users post. How cheeky are they?

NOTE: I changed the images because after a while they didn't appear. The URL is http://f1-dictionary.110mb.com/pushrod_pullrod.html

BTW, the guy gives credit to F1Tech. He says - f1technical.net, , a great site with a lot of technical information’s and explanations. Talk about being mistaken...