Pushrods and pullrods

[DorianF1]

Hello all!

I'm totally new to this community, but I'm not that new F1 fan as I've been following it for over a decade.
Now I'm trying to learn more about technical side of this sport, so I've got many questions connected with that. Please don't get angry if they may sound a bit trivial to you
First of all, I'd like to learn everything about suspension and so I want to ask you for clarification. Please, write here everything you know about pushrod and pullrod systems, all the differences between them, advantages and disadvantages and maybe a bit of history (I've read somewhere that Arrows used pullrods for the last time in 2000, but I'm not 100% sure of it)

THANKS A LOT IN ADVANCE!!!

DorianF1

[Monstrobolaxa]

Well.....Minardi also used a pullrod suspension in 2001.

- a pushrod suspension has the suspension arm (pushrod) going from the bottom of the wheel to the top of the monocoque, like the name says this suspension arm is pushed, compressing the damper (through the rocker).

- a pullrod suspension has the suspension arm (pullrod) going from the top of the wheel to the bottom of the monocoque, like the name says this suspension arm is pulled, which will also pull the damper (through the rocker).

one of the disadvantages of a pull rod suspension is the positioning of the suspension elements which makes life more dificult to change the setup. One of the main advantages is the fact the it reduces the height of the cofg in thefront suspension.

here is a link about pull rod suspensions:

http://www.scarbsf1.com/pushrod.html

[Guest]

the reason for doing pull or pushrods are :
Aero:Get the dirty springs and dampers out of the airstream between tyre and tub.In the seventies/eightess this was achieved by rockerarms but these had to be quite massive and so the neater pull and pushrods came.

Unsprung mass:Damper and Springwill count fully to the sprung mass ,helping the unsprung masses,wich is good news for grip/traction

Progression in spring utting the Spring directly and anled onto the wishbone provides usually a digressive springrate wich is highly unwanted.
So as the cars springs get compressed the effective springrate gets less and less as the spring/damper gets shorter and leans down more and more.
The Push/pullrod thing allows allmost anything in terms of progression
Adjustability:Changing rideheight by changing the pushrod length does not affect the damper/Spring adjustment (bump/droop travel) so rideheight changes are separated from spring/damping.

I think the first to use Pullrod was Gordon Murray in the 1973 Brabham BT42 or BT44 .
marcush.

[DorianF1]

Thanks guys!

It really helped me. But I've read in F1 magazine that pushrods push the wheel up when travelling on the straights. It sounds really stange. I think they meant that wheel is pushed atop damper when driving over kerbs and bumps. Am I right???

DorianF1

[Guest]

You won´t believe what journos write without having a clue...most of the time the people involved would bet the writer of the article saw a different race or was not even watching the race.....don´t believe everything just because it is written down and published.
Of course you could incorporate a hydraulic device into a pushrod to regulate rideheight thou...would be clever but illegal as this would make the car body a movable aerodynamic device and as such it is illegal.
marcush.

[West]

Thanks guys!

It really helped me. But I've read in F1 magazine that pushrods push the wheel up when travelling on the straights. It sounds really stange. I think they meant that wheel is pushed atop damper when driving over kerbs and bumps. Am I right???

DorianF1

Hopefully F1 racing meant that the wheel pushes the rocker arm of the suspension, with the torsion bar acting against the arm. Going down the straights, the wheel will encounter a bump probably and force the pushrod to activate. I don't think F1 racing is full of idiots; they probably don't know how to put it in words.

[DorianF1]

I don't think F1 racing is full of idiots; they probably don't know how to put it in words.

Thanks West!

Now I've got clearer picture of that situation. But tell me... if it's true that pushrods push the wheel up in the air while the speed and aero load increase??? I wonder as I've heard it somewhere.

DorianF1

[Guest]

F1 cars are cars and nothing else.
Cars normally ride on springs in formula 1 these springs happen to be conected to the suspension by pushrods,wich is essentially a straight bar with spherical joints at each end,they have no other task than transmitting the forces to and from the springs and dampers.end of story.

[West]

I don't think F1 racing is full of idiots; they probably don't know how to put it in words.

Thanks West!

Now I've got clearer picture of that situation. But tell me... if it's true that pushrods push the wheel up in the air while the speed and aero load increase??? I wonder as I've heard it somewhere.

DorianF1

I'm not sure, but pushrods shouldn't push the wheel up at all under aerodynamic loading. A pushrod only is activated when the wheel encounters a bump in the road or is subjected to cornering forces.

http://www.scarbsf1.com

Go here and you'll see a pushrod suspension setup... follow the diagram correctly and you'll see how a pushrod works.

[dumrick]

pushrods push the wheel up in the air while the speed and aero load increase???

What is meant is that, when speed increases, so does the aero load. That pushes the car down, compressing the spring. Therefore, the ride height is lower at greater speeds.

[DorianF1]

pushrods push the wheel up in the air while the speed and aero load increase???

What is meant is that, when speed increases, so does the aero load. That pushes the car down, compressing the spring. Therefore, the ride height is lower at greater speeds.

And that's the explenation I was waiting for! Thanks Dumrick!

[Guest]

Hi guys,

I am a 14 yr old f1 fan....have been confused by this term wheel travel... can someone clarify wht it means....
thx guys..

[Guest]

Wheel travel is the amount that the wheel travels up and down relative to the chassis. If you suspend a car in the air, and then push one wheel as far up as it will go, the difference between how low it goes, and how high is measured as wheel travel. For example, a motocrosser can have wheel travel of 18 inches. But a Formula One car's suspension moves up and down very little, probably less than three inches.