The other active suspension cars - Leyton House

[DaveW]

I'm pretty sure the early 90's Williams F1 cars used a true electro-hydraulic system.

You could be right, but the actuators shown in your first clip are best described as "hydraulic rockers", I think, despite the fact that the design also incorporated mechanical rockers (the mechanical rockers were deleted eventually). The bit that matters is kept well hidden....

Tim referenced the system that WGP used in 1987, I believe. That clearly used passive dampers (see Fig 3 of Tim's reference), and passive springs (air or gas trapped in the accumulators). Ride height was controlled by EHVS' that were updated "sufficiently frequently" (64 frames/sec). In my view the system described is a series design. Nothing wrong with it in principle, but preventing the ride height controller coupling with the passive elements must have been a challenge.

[riff_raff]

riff_raff the second video you posted is a video game rFactor2, not the clip I think you wanted

Thanks! Sorry I didn't take the time to check the video before posting.

Here's a better example of on-car video of Mansell driving the FW14 that shows how effective the active suspension was at controlling chassis pitch and roll. Compare the movement of the front suspension versus the front wing as he drives over the curbs.

https://www.youtube.com/watch?v=FTT5VL8NuEM

[DaveW]

... on-car video ... shows how effective the active suspension was at controlling chassis pitch and roll. Compare the movement of the front suspension versus the front wing as he drives over the curbs.

Mmm... The video is interesting, however, so thanks for that. Do you have anything at all on the Leyton House system...?

[DaveW]

I'm pretty sure the early 90's Williams F1 cars used a true electro-hydraulic system.

You could be right, but here, courtesy of Nigel Mansell, is an image extracted from this video of the FW14B.

Hard to make out the details, but what appears to be a cross-link between the front actuators would not, I think, be required on a true electro-hydraulic design.

What do you think?

[riff_raff]

I looked at the screen grab you posted of the FW14B front end. I could not see any mechanical link between the L/R sides. The two fluid hoses coming out of the upper end of each hydraulic actuator, and connected to the transverse cylindrical manifold between them, are likely return lines. It is common with high-performance hydraulic systems to design them such that the fluid continually circulates in a loop, rather than simply back-and-forth between the actuator and pressure accumulator. This allows the hydraulic fluid to be cooled, filtered, etc.

Just my guess though.

[DaveW]

The two fluid hoses coming out of the upper end of each hydraulic actuator, and connected to the transverse cylindrical manifold between them, are likely return lines.

The three EHSV's located at the rear of the assembly (underneath the temperature stickers) would be attached to both the supply & return lines. Why would the actuators be attached to return lines...?

Logically, if the system is hydro-pneumatic, a mechanism would be required to control roll motion, which is , I believe, housed in & on the "transverse cylindrical manifold". If the system was "true electro-hydraulic" suspension motion (including roll) would be controlled by software, and no cross linking would be necessary.

[autogyro]

Perhaps it had something to do with Patrick Head and his interest in electro hydraulic roll systems.
It would be interesting to find out how much Adrian Newey brought over from his experience to Leyton House and just what remained of the development on the Red Bull cars.

[BanMeToo]

Here's a better example of on-car video of Mansell driving the FW14 that shows how effective the active suspension was at controlling chassis pitch and roll. Compare the movement of the front suspension versus the front wing as he drives over the curbs.

https://www.youtube.com/watch?v=FTT5VL8NuEM

Kind of eerie actually

[R_Redding]

I'm fairly sure it was electro (moog-valve) -> hydraulic control.

On this pic of the front suspension and tub ,you can see the double acting (brass coloured) actuator cylinders and the moogs sat on the hydraulic manifold.

[DaveW]

I'm fairly sure it was electro (moog-valve) -> hydraulic control.

That depends on your definition of "electro->hydraulic" control.

On this pic of the front suspension and tub ,you can see the double acting (brass coloured) actuator cylinders and the moogs sat on the hydraulic manifold.

I don't disagree with you in principle, but it would be fairly easy to interpret what can be seen as part of a hydro-mechanical system, similar to that introduced by Citroen see, for example, this and this. In that case the actuators would not be double acting (in the conventional sense).

Why would three ESHV's be required at the front suspension?

[riff_raff]

My interpretation of electro-hydraulic is a system that relies on electrically controlled valving, as opposed to mechanically controlled valving.

[DaveW]

My interpretation of electro-hydraulic is a system that relies on electrically controlled valving, as opposed to mechanically controlled valving.

So how would describe a (series) system with (electrically) controlled ride height, but passive dampers & springs?

That type of system (aka fast ride height control) came to be used widely in F1 to lower ride height on track, and increase ride height in the pit lane (for the ride height test), until the "plank" was introduced. My guess would be that the Leyton House system was one of those.

[matt21]

My interpretation of electro-hydraulic is a system that relies on electrically controlled valving, as opposed to mechanically controlled valving.

So how would describe a (series) system with (electrically) controlled ride height, but passive dampers & springs?

That type of system (aka fast ride height control) came to be used widely in F1 to lower ride height on track, and increase ride height in the pit lane (for the ride height test), until the "plank" was introduced. My guess would be that the Layton House system was one of those.

To be honest, I never heard of something like this. How does this work? By adjusting lever length or spring base?

[DaveW]

To be honest, I never heard of something like this. How does this work? By adjusting lever length or spring base?

Either way. You might like to consult Tim.Wright's reference at the bottom of Page 1. This was an article written by Scarbs using a patent published by Frank Dernie in 1989 (US4861066).

Figure 3 of this document showed a passive damper (conventional) & nonlinear spring (air trapped in the accumulator) This is screwed into 69 in figure 2, which otherwise shows the ride height adjuster. Alternative arrangements might replace figure 3 with a simple coil-over damper bolted to the top of the ride height adjuster, or the ride height adjuster could take the form of controllable variable length spring platform mounted on the outside of the damper, etc. None of it is magic (apologies)...

[riff_raff]

I went back and looked at the patent document noted. It was a bit complicated, but from what I could tell it was not exactly the same arrangement shown in the photo of R_Redding's post. The patent documents describe a digital-electric (Moog!) servo valve regulated hydraulic actuation system that uses nitrogen gas primarily for dampening and compliance, but the suspension movement is still controlled by hydraulics.

Note that figure 3 of the patent shows a hydraulic strut with only one fluid port, as opposed to the hydraulic struts in the photo above that show two fluid connections.

As for "mechanical" coupling of the L/R hydraulic struts, here's what the patent says: "...Similarly, the front pressure sensor 41 and outer pressure sensor 42 when the vehicle is cornering hard, will cause the computer to cause the outer rear strut 6 to be lengthened to compensate for radial compression of the outer tyres...." This would seem to imply that roll control is electronically regulated.