What the 'Fric' is it?

[gt6racer]

Sorry, perhaps I should have continued my question to include the logical provision ".......within the confines of current regulations."

[WhiteBlue]

I have now developed (what I think is) a working model of the front/rear coupling so I should be in fairly reasonable shape to interpret what I measure when I do actually meet one.

Why don't you give us a sketch of the hydro mechanical system as you suspects it is designed. It would transport you ideas much better than many words.

[matt21]

Maybe something like this.
Sorry it is in german but the picture should be self-explaining.


Here is the complete document (also in German).
But I can explain if needed. Just let me know.

http://www.tots-parts.com/audi_web/inte ... hrwerk.pdf

[bonjon1979]

On a side note, I read in a book the other day that thermometres not allowed on planes because they contain mercury which if spilled could react with the aluminium used to make the aircraft. Would this mean that any team wanting to use mercury in their fric system would have to source the fluid in whatever region they're racing or deliver it by boat/road?

[timbo]

On a side note, I read in a book the other day that thermometres not allowed on planes because they contain mercury which if spilled could react with the aluminium used to make the aircraft. Would this mean that any team wanting to use mercury in their fric system would have to source the fluid in whatever region they're racing or deliver it by boat/road?

I guess a standard measures for transportation of hazardous/danger substances would be used. The thermometers are easy thing to break. A specially designed container is a different matter.

[Richard]

That thermometer story sounds like an urban myth to me. I struggle to see how the tiny amount of mercury could pose a serious danger to the structure.

Anyway, why use conjecture when we can find out the facts?

The CAA says that personal thermometers are allowed in the hold and the passenger compartment, while meteorological thermometers and barometers are banned from cargo – perhaps the lower pressure causes risk of damage? http://www.caa.co.uk/docs/1219/srg_dgo_ ... 120321.pdf

There’s a lot more info here...

International Air Transport Association (IATA) Packing Instruction 803 allows transporting flasks containing less than 35 kg of mercury. The flask must pass the 95 kPa pressure test for liquids by air (IATA 5.0.2.9).

http://www.mercurynetwork.org.uk/wp-con ... arroll.pdf

No apologies for letting facts get in the way of "I once read in a book"

[gt6racer]

Matt21 - That is Yamaha XREAS which has been around for a while - was used on Toyota 4Runner too. It's a modal damping system only, (extra damping in roll/pitch than in heave) and does not offer roll/pitch spring stiffness.

I'd echo the plea for DaveW to please share a schematic of his thoughts.

[flynfrog]

there is really no reason you need mercury there are plenty of other high density fluids out there.

[DaveW]

Maybe something like this.

That looks very like a hydraulically linked third (front or rear), but with added roll damping, apparently.

Why don't you give us a sketch of the hydro mechanical system as you suspects it is designed. It would transport you ideas much better than many words.

My model is just that, a model with the ability the simulate rig tests and execute some steady state maneuvers. I think that techFILES found a very good photograph of a plausible front suspension layout. I liked some of the amendments to his original post, particularity the dropping of the "crushing" analogy.

Unfortunately, it isn't clear whether Minardi used hydraulic or conventional springs. It seems that two hoses are connected to the rear (I guess). I also guess that the visible hardware implemented a hydraulically linked front third, something fairly similar to the sketches posted by matt21, but with no third damping, I think.

Interestingly, Tyrrell used something similar, as pointed out by timbo. Their front actuators functioned as hydraulic rockers connecting a damper and coil-over spring to the push rod. I rig tested the vehicle in 1996 (when it was configured only as a rocker). It had some issues (I recall), mainly friction & compliance.

[langwadt]

That thermometer story sounds like an urban myth to me. I struggle to see how the tiny amount of mercury could pose a serious danger to the structure.

https://www.youtube.com/watch?v=Z7Ilxsu-JlY

[Richard]

Wow - Thanks for that.

[ringo]

Maybe something like this.
Sorry it is in german but the picture should be self-explaining.
http://s7.directupload.net/images/130508/kwjxgk8r.jpg

Here is the complete document (also in German).
But I can explain if needed. Just let me know.

http://www.tots-parts.com/audi_web/inte ... hrwerk.pdf

Well what is clear is that hydraulics are used in suspension to transfer forces to remote locations mainly.
That air spring in the middle is basically an anti roll bar. So this model is the equivalent of a mechanical model, only that due to the nature of the air spring, and it's housing adjust-ability may be electronic.

[henry]

Maybe something like this.

That looks very like a hydraulically linked third (front or rear), but with added roll damping, apparently.

My reading is that the additional damping is there whenever the two spring/ damper units at each end are out of phase. Because of the diagonal connection, front/rear, this would be roll and pitch. I think warp might get some as well but I'm not sure. I think the spring is there to stop the system being "infinitely" stiff when the units are in phase. I think the text in the reference refers to its use for comfort.

The results section shows reduced and more stable pitch under braking, and less roll, when the system is in use. Looks like the sort of benefits that would be sought after from FRIC.

[DaveW]

My reading is .....

Good comments, but surely the "damping" of the central module would slow down the transfer of fluid between the two axles.

[gt6racer]

Henry, you are spot on. To add, as the system only connects diagonally and so for damping it doesn't recognize warp as being different to heave - so no damping addition. ( There is a small spring effect difference as one set extends and the other compresses, but it's neglible in the grand scheme). I'd question the comfort benefit - the system also picks up some of the added damping for single wheel input - generally it's used for the added pitch/roll control.
I doubt this is FRIC - the contribution is too small for the complexity - my money is on FRIC being a four wheel (there are also side/side connections - not just front rear) modal stiffness system, with gas for springing which can also provide modal damping. ( Using accumulators, stiffness is generated by flow in or out - damp that flow and you have additional damping in combination with stiffness ). With such an approach it is quite possible to develop a suspension with zero warp stiffness - ie no change of wheel load with warp travel - wouldn't that be nice for traction/yaw stability and tire wear !
Dave, with fluid assumed "incompressible" it can't slow it down, but it does generate a pressure increase before the valve, which translates into the added force at the piston rod. (Obviously the damping might slow the suspension motion - if that's what you meant )