types of suspensions

[effuno]

been reading about different types of suspension systems prep for my exams , but the buk does not explain its relative merits.

1 so can someone pls explain the advs and disadvs of double
wishbone susp, macpherson strut susp, pushrod susp , trailing arm
susp , control arm susp and multilink susp .

2 why is double wishbone and pushrod pref for F1 car?

3 what exactly is a multilink susp? is wishbone susp a multilink susp?

4 can a double wishbone susp be macherson strut susp ? (i rem having
heard of that once but cant recollect where)

[Ayrton]

What you ask is a topic of a thousand pages + but just to answer quickly...

a double wishbone suspension is merely a suspension system with two control arms...an upper and lower control arm. These control arms connect the upright to the chassis. To activate the suspension you need a link to connect the upright to the dampers and springs so you can use a pullrod (rod is in tension) or a pushrod (rod is in compression).

A macpherson system has a lower control arm and a strut which replaces the upper control arm and pushrod from the double wishbone system.

Some main advantages of the double wishbone setup is the ability to have lots of camber gain in compression by using different length arms... short UCA (upper control arm) and longer LCA.

A big disadvantage is packaging.

There are many SAE papers, books and websites with a great wealth of information.

[Steven]

As for your second question, F1 cars are today all using pushrods. These are connected on the lower side of the upright and high onto the monocoque. This rod is therefore pushing the wheel down, or if you prefer, pushing the car up.

Pullrods are the adverse as they pull since they are connected on the top of the uprights and very low on the monocoque.

These pullrod systems used to be seen in F1 quite often, but have disappeared totally (I think the last one was the Arrows A22). Pushrods are preferred today as with the high noses it is impossible to attach the pullrod low onto the monocoque without having to alter it with aerodynamic disadvantages.

[Ciro Pabón]

Well, I guess you already have seen the comparison between different types of suspensions at HowStuffWorks and Wikipedia. Or maybe not.

I just take the opportunity to ask: have you heard of the Bose suspension?

[marcush.]

i don´t think the current double wishbone layouts are necessary.One gets the impression that more and more teams go for aerodriven solutions with regard to their suspension geometries...with current suspension movement in bump and rebound compared to the movement within the tyre sidewalls ,it looks like installation stiffness (blade type joints to the chassis) and damping are the key targets,and a bit of steering geometry.
I wonder why just nobody has gone as far as having one piece longitudinal swingarms yet.You could surely build incredibly stiff suspension links with enough elasticity in the required modes and clean up the Aero in the same process ...plus put the weight lower into the car ....
todays cars take the evolutionary approach the CAD/CFD/FEM boffins optimise each part again and again using the available tools no end.unfortunatelly Computer screens do not actually encourage innovation...and given the budgets plus the cost cutting politics we´ll see double wishbone systems for some time in the future...

[Jersey Tom]

A-arm suspensions lend themselves to being easy to package, have great control over wheel movement, and are fairly robust due to very little if any bending loads. Thus very lightweight. I think for our '06 FSAE car all of our suspension arms totalled 8 lbs. And we could still pull weight out of them.

Don't know if you could get swingarms that light, or have anywhere near the amount of adjustability.

[effuno]

a double wishbone suspension is merely a suspension system with two control arms...an upper and lower control arm. T

thanks everyone for the replys!! but doesnt control arm and wishbone arm differ ? i was under the impression that control arms are V shaped PLATES while wishbone arms are V shaped bars



can someone explain how exactly a pullrod works ..( the name gives an idea ,but its better to clarify..)

[effuno]

I wonder why just nobody has gone as far as having one piece longitudinal swingarms yet.You could surely build incredibly stiff suspension links with enough elasticity in the required modes and clean up the Aero in the same process ...plus put the weight lower into the car ....

marcush , doesnt swingarm suspension creates complexities in dampening area!! i heard some say dampening in bikes are more difficult to control than in cars and bikes use swingarms , dont they ? maybe the weight distribution may be the factor ! i'm not an expert in this !! corrections welcome !!



found an ans to 3rd and 4th question !!

multilinks susp are a kind of wishbone susp with independent arms in each wishbone rather than the ridily joined together arms in a wishbone susp !!


alfa romeo 166 has a classic macpherson strut and double wishbone multilink setup at rear to provide comfort and aid handling !! source : autocar india, april 2004 !!

[RH1300S]

A arms are very efficient at transmitting loads as already described. Also easy to adjust to get the geometry required.

A swing arm would need a very big section to resist twisting and side bending forces. How would you engineer a camber curve? It's a vision I like the idea of 'though

I don't believe motorbikes have any problems damping the suspension at all. The big thing with bikes is controlled flex. They have found that totally rigid frames and swinging arms are slower than ones that flex. When a bike is leaned over, some controlled "give" makes it grip better and is easier to control - the black art these guys are into is getting the right amount of flex in the right places/directions (you can have too much flex in the wrong direction)

[effuno]

The big thing with bikes is controlled flex. They have found that totally rigid frames and swinging arms are slower than ones that flex. When a bike is leaned over, some controlled "give" makes it grip better and is easier to control - the black art these guys are into is getting the right amount of flex in the right places/directions (you can have too much flex in the wrong direction)

does flex refer to the movement abt the point joining swing arms to frame ?

[RH1300S]

does flex refer to the movement abt the point joining swing arms to frame ?

Sort of.

Think about it as flex somewhere between the rear axle and the steering pivot (headstock).

To be honest I read about this a while back and forget the exact details. I know that where it flexes and how much matters a lot. When a bike is laid over, the side-side flex can help with feel and grip. BUT when a bike is upright and accelerating - a side flex at the swing arm (the drive chain pulls along one side of it) can make it quite unstable.

Must be very tough to get right. At the highest level I suspect that it varies from rider to rider.

I'm running out of a very shallow knowledge pool here - if I say much more I wil probably mislead you. Sorry.