Steering Strut

[Ciro Pabón]

Why would you ever want to rigidly bolt it to the upright?.... Unless I'm missing something obvious..

I do not know about F1, but this is the strut tower brace a.k.a. steering strut for the steering mechanism of a Cobra 68 that you can buy here. Could they use something similar in F1? I am pretty sure the Audi A8, Mazda Miata and the Chevy Camaro use something similar.



This thing is used to rigidize the steering mechanism, so you do not get the lateral bending you have when you drive over roads that have a regular pattern of bumps, like some dirt roads (surfaced with non-plastic material, like gravel or sand) or, for example, a railroad track.

Just visualize the wheel when turned and imagine it hits something perpendicular to it: the entire mechanism has low rigidity in this direction, if you get my drift.

I would say they could use this kind of strut in F1, as it gives a crisper steering response, but, please, do not ask me where it is located.

As I am no mechanichal engineer I wonder if I am jumping to conclusions. Just in case, where can I apply for the interview?

[Ciro Pabón]

I found the same strut for the Miata with a short explanation on what it does.

http://www.gomiata.com/sttobr.html

[manchild]

I really don't see why anyone would risk experimenting in weight reduction on rack and pinion including steering column (axle). CF for tie rods is ok having in mind type of forces they deal with but anything except steel seams too risky for rack, pinion and steering column (axle). Clay Regazzoni ended up in wheelchair for life after some genius decided to reduce weight of brake pedal using titanium instead of steel (titanium pedal broke in two pieces under foot pressure). Aluminum seams out of the question except for rack and pinion casing as well as titanium (good elasticity isn't something needed in steering system).

Apart from that there is also FIA steering column test which logically excludes certain materials that would make steering system work but couldn’t pass this test for sure (unless over-dimensioned).

16.5 Steering column test:
The parts referred to in Article 10.4.4 must be fitted to a representative test structure, any other parts which could materially affect the outcome of the test must also be fitted. The test structure must be solidly fixed to the ground and a solid object, having a mass of 8kg and travelling at a velocity of 7m/s, will be projected into it.
The object used for this test must be hemispherical with a diameter of 165mm.
For the test, the centre of the hemisphere must strike the structure at the centre of the steering wheel along the same axis as the main part of the steering column.
During the test the striking object may not pivot in any axis and the test structure may be supported in any way provided this does not increase the impact resistance of the parts being tested.
The resistance of the test structure must be such that during the impact the peak deceleration of the object does not exceed 80g for more than a cumulative 3ms, this being measured only in the direction of impact.
After the test, all substantial deformation must be within the steering column and the steering wheel quick release mechanism must still function normally.

[MrT]

These guys are right, the steering struts do not experiance bending in f1 as they are not mounted rigidly to the upright as you have suggested. They are mounted using spherical bearings at each end (sometimes a ball and socket design on the rack end but anyway) which means that because it is pivoted at each end the rod may only transmit tension or compression forces only.

I have never seen a steering arm mounted in the way you have suggested on any single seater race car, and not in F1 either.[/quote]

[NickT]

Having read some of the other posts here I have realised there is still some confusion so I looked carefully once more at what was written.

I have been informed that: "the title given as 'The design and analysis of a composite F1 front steering strut' is referring to the steering arm. This is long push-rod that controls the direction of the wheels."

This first piece that I picked up on was "the steering arm".

is referring to the steering arm

As I said this is the arm attached to the upright and hub assembly, almost parallel (depending on Ackerman angle) to the wheel. This is the arm that turns the upright around the King pin (the line between the upper and lower out board suspension points). This steering arm works almost continuously in a bending moment.

Then I reread this

This is long push-rod that controls the direction of the wheels

This is some thing different; this is the steering rod or tie rod. This connects the steering rack to the "suspension arm" and transfers the movement of the rack to the steering arm. As has been quite rightly pointed out, works only in both in compression and under tension..

If this is the case, and suspect it is, then I would strongly recommend following MrT's great advice. Although I personally would add that you will need to take into account some bending moment requirement for someone accidentally sitting or standing on it while stationary

Steering struts do tend to be composites i think. They will be woven using helical, circumferential or polar winding techniques around a given core material. Pretty sure they are a plain composite as well e.g. carbon and not a hybrid for example carbon-Kevlar.

You would best begin looking not at specific steering strut manufacture but reading composite books and looking at how struts are generally made. Don't jump in to the hard bit till you have a good fundamental understanding of the composites first - I've seen many get in a mess doing it this way!

Apologies for any confusion

[MrT]

Thanks NickT, I agree with what you say about bending moments induced by outside factors for example someone leaning against it - However I'm pretty sure that F1 don;t take these outside factors into account during design as i think that any strut for this application that will not fail by buckling due to the imposed compression forces will be sturdy enougth to resist such irregular imposed forces.

[flynfrog]

Having read some of the other posts here I have realised there is still some confusion so I looked carefully once more at what was written.

I have been informed that: "the title given as 'The design and analysis of a composite F1 front steering strut' is referring to the steering arm. This is long push-rod that controls the direction of the wheels."

This first piece that I picked up on was "the steering arm".

is referring to the steering arm

As I said this is the arm attached to the upright and hub assembly, almost parallel (depending on Ackerman angle) to the wheel. This is the arm that turns the upright around the King pin (the line between the upper and lower out board suspension points). This steering arm works almost continuously in a bending moment.

Then I reread this

This is long push-rod that controls the direction of the wheels

This is some thing different; this is the steering rod or tie rod. This connects the steering rack to the "suspension arm" and transfers the movement of the rack to the steering arm. As has been quite rightly pointed out, works only in both in compression and under tension..

If this is the case, and suspect it is, then I would strongly recommend following MrT's great advice. Although I personally would add that you will need to take into account some bending moment requirement for someone accidentally sitting or standing on it while stationary

Steering struts do tend to be composites i think. They will be woven using helical, circumferential or polar winding techniques around a given core material. Pretty sure they are a plain composite as well e.g. carbon and not a hybrid for example carbon-Kevlar.

You would best begin looking not at specific steering strut manufacture but reading composite books and looking at how struts are generally made. Don't jump in to the hard bit till you have a good fundamental understanding of the composites first - I've seen many get in a mess doing it this way!

Apologies for any confusion

i dissagree somewhat ive desinged a few race cars annd we build them to do exactly there job then train the people around them not to sit on this part or lean on that part

remeber how much weight cost i dont think an f1 desinger would add it becasue some one might lean aginst it notice they dont let jsut anybody into the pit

[Jersey Tom]

Yea. I've never seen a-arms or pushrods or anything designed to withstand idiot forces.

Many nights moving FSAE cars.. "dont lift the car by the a-arms!!"

[RacingManiac]

Yea. I've never seen a-arms or pushrods or anything designed to withstand idiot forces.

Many nights moving FSAE cars.. "dont lift the car by the a-arms!!"

I thought we are the only one....

[wuming]

Just wanted to say thanks to all you guys for your help. I never thought there would be so many replies, so thank you very much!

(just so you know I have just finished my degree at Coventry Uni in Automotive Engineering)

Thanks again for all your help!

Simon

[MrT]

Feels good don't it! Just finished Motorsport Engineering and Design degree in Swansea!

[wuming]

Hello again!

Its coming along quite well - I am getting there. All I am really missing is a picture of one labled on the car type of thing, and I wondered if anyone could point out which one of the several struts going to the wheels the tie rod is?

Or is it completely different on all the cars?

Thanks alot!

[manchild]

Hello again!

Its coming along quite well - I am getting there. All I am really missing is a picture of one labled on the car type of thing, and I wondered if anyone could point out which one of the several struts going to the wheels the tie rod is?

Or is it completely different on all the cars?

Thanks alot!

No you're not missing because it is not there. That thing on pic is just rigid construction used to make chassis/bodywork stiffer and therefore enable better steering response/handling. No such thing is used in f1.

Check these pics.

http://www.gurneyflap.com/Resources/DeriveenVTS.jpg
http://www.gurneyflap.com/Resources/CreveAVTS2.jpg
http://www.gurneyflap.com/Resources/CreveAVTS.jpg
http://www.gurneyflap.com/Resources/frontsus.jpg
http://www.gurneyflap.com/Resources/113_1338.jpg

[wuming]

yeah i know, im not referring to the picture.

If you look at any picutre of an F1 car there are several struts going from the body work out to the wheel at the front. I want to know which is the tie rod as opposed to a wishbone. Is it the one that is normally going diagonally backwards slightly (ie back of the wheel connecting further back on the body and slightly upwards) ?

I hope my description is ok...

[manchild]

[IMG:152:106]http://img123.imageshack.us/img123/1168/s18tz.th.jpg[/img]
Click to enlarge!

0. Tie rod
1. Lower suspension arm (wishbone)
2. Rack and pinion
3. Rocker
4. Upper suspension arm (wishbone)
5. Pushrod
6. Steering column (axle connecting rack and pinion with steering wheel)

Tie rods alone (not F1 but very simmilar)