F1 Pneumatic Valve Spring, a closer look

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
Brian.G
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F1 Pneumatic Valve Spring, a closer look

Post by Brian.G » Thu Sep 15, 2016 4:53 am

Another part under the spot light, and possibly one that cost the most time and effort obtaining.

In this thread I will be unlocking a few secrets hidden within this part - The Pneumatic Valve Spring, mainly its construction, the parts inside and how they go together. To my knowledge, this is the first time a complete Pneumatic Valve Spring has ever been seen in the public domain in its entirety - exposing all components in great detail. While I have in the past shown parts of an older style assembly - this Pneumatic Valve Spring is from one of the last V8 engines, and one that had a 20,000rpm+ rev limit. I am aware that a similar Pneumatic Valve Spring has featured in the past in a Magazine, but the article was disappointing to say the least in terms of displaying and describing possibly one of the most interesting and critical parts within any F1 engine we have seen so far. Given the new lower engine rpm operating range which is now in place, we may never again see or have use for such an assembly of which huge performance demands were placed upon it.

These Pneumatic Valve Springs are now available to purchase at considerable cost, but actually finding a vendor that will take you serious definitely out-weighted the cost on this one.

I am not going to mention the engine makers name all the same just In-case Ive missed some small print.

In terms of Engineering Design, getting my hands on this Pneumatic Valve Spring meant a lot to me. I'm years trying to obtain one - I got so close so many times and the deal would either fall through, or the assembly would be incomplete on close inspection. I owe a huge thanks to many people along the way that took pictures of what they had or patiently replied to countless emails, from memorabilia specialists, to F1 Mechanics, Random ebayers, all the way to F1 Engine Manufacturers. I owe a huge and special thanks to the Company that was able to supply in the end - having this item now closes an unfinished chapter for me that was always in the back of my mind. I believe the Design Engineers that managed to create this assembly and get it to be reliable deserve recognition for years to come - as mentioned, it may never be done again.

Enough of the back story and onto the part.

First off, the smallness of the Pneumatic Valve Spring surprised me, as did the method used to manufacture the bore/barrel assembly. Since I had obtained a much older assembly years ago I have something to compare the much later and higher revving design to - the 10yr(approx) gap between both designs is now very apparent.

Below is the full Pneumatic Valve Spring assembly pictured in its complete state. I've decided the best way to display all is to break down the assembly in stages and try describe each part as I progress.

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A shot down the top of the lash cap still affixed to valve stem on which the finger follower presses,

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A shot of the valve exiting lower sealing disk as well as the separate valve guide, valve stem diameter is just 5mm. Since this is the base of the assembly it is this side that sits onto head - for clarity I have removed the sealing o-ring from the groove which can be seen below. This o-ring seals the disc containing lower valve seal to both the main assembly body, and also the cylinder head mounting area,

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Side of assembly, showing bore liner retainer ring, this gets held on with main assembly to head fixing screws,

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You can just see the top outer ring of steel bore liner and how its held down with retainer ring, take note too of the over pressure bleed drilling exiting relief valve area,

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Again, the relief valve drilling and cap screw - under this screw is a spring and small valve seat - this controls over pressure under pneumatic piston - opening in over pressure conditions and bleeding off excess Nitrogen,

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Now lets start to strip down the Pneumatic Valve Assembly and discuss each component,

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The piston and seal is a pretty tight sliding fit in the bore,

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With the reciprocating parts removed it is now easier study the main body, below the bore liner retainer is withdrawn,

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Since the main body is cnc machined aluminium(tested/confirmed) it is then fitted with a steel liner sleeve which is pressed in. Given that aluminium expands more that steel I'm guessing they added the retainer above ring for added security.

The steel bore liner can clearly be seen as a separate part below,

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Looking at the bottom of part the lower disc can now be removed - take note of the o-ring groove mentioned above,

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A view from inside before removal,

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Removed, lower side pictured - faces onto head, stem air seal in middle,

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Top side of disc, worth taking note of seal orientation, the air pressure forcing seal out and against valve stem,

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The seal removed, the seal is quite hard and I would suspect something by Parker and Graphite filled PTFE, - spring energized. It is also now apparent that the stiction caused by the stem seal, and also the main piston seal is enough to prevent the valve from dropping when shutdown, thus doing away with any form of weak spring that was in the past used to prevent valve drop.

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Top of stem adjacent to seal in normal operating conditions,

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A small lip prevents disc from rising off head face and into area under piston, take note also of drilling out to relief valve,

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The air in drilling too - tapping into the vertical drilling which gets its supply from head face where the assembly mounts onto,

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A shot of the cross hatch pattern on steel liner wall resulting from honing, the hatch pattern encouraging oil retention much like a normal engine cylinder. From looking at it the steel liner material seems to be a high chrome type tool steel type so as to prevent corrosion. It is worth noting too that in the past much r+d has be carried out in terms of plating aluminium style pneumatic assemblies - even teflon impregnation of the anodic film. Here they used a more traditional steel liner, albeit a very thin one,

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Minimal liner thickness, steel is heavy and it is also 'a high up position' on the engine in terms of center of gravity. They have also lightened the aluminum body internally as much as possible by milling out all excess material at the base of liner,

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The pressure relief valve and associated parts,

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The actual valve being a steel ball in what is probably an aluminium bronze locator,

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There is also an aluminium bronze seat deep inside the relief valve drilling/housing which the ball seats on.

That concludes the main F1 Pneumatic Valve Assembly Body.

Onto the piston, lash cap, retainer-piston, and collets/cotters pictured below,

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There is nothing too unusual about this layout - the collets/cotters not unlike any modern parts. The lash cap locates onto valve and is kept from falling off by an internal snap ring within the lash cap,

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The collets fit snugly on the valve stem,

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And locate as they normally do into the retainer-piston,

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The lower side of the retainer piston contains an o-ring with is a snug fit on the valve stem - thus sealing off any air from exiting here,

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Fitted,

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Lash cap fitted,

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The piston retainer cross-section below, notice again a spring energized graphite filled PTFE seal - piston is aluminium and all excess material removed for lightness - keep in mind this has an approx stroke of 13.5mm, and does so 340 odd times a second!

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Three small grooves on the top edge of piston seal allow some cam tray oil mist to make its way onto seal lip/liner interface,

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With all of the above in mind I hope the thread and information here has helped everyone from Casual Viewers, Enthusiasts, F1 fans, Engineers, Designers, Students, and Teachers Worldwide - If you know anyone whom you think would like to see it please share this link.

All pictures are backed up and on prepay hosting so they are not going to vanish anytime soon - hopefully now there is no doubt as to what a modern day 20,000rpm Formula One Pneumatic Valve Spring Assembly actually looks like inside, and how it all fits together.

All the Best,

Brian Garvey.
Last edited by Brian.G on Sat Sep 24, 2016 1:16 am, edited 1 time in total.
If you think you cant, you wont, If you think you can, you will

graham.reeds
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Re: F1 Pneumatic Valve Spring, a closer look

Post by graham.reeds » Thu Sep 15, 2016 7:30 am

Nice.

Could you post a picture of it sat next to a coin for a size reference?

Brian Coat
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Re: F1 Pneumatic Valve Spring, a closer look

Post by Brian Coat » Thu Sep 15, 2016 8:41 am

Thank you, Brian.

I think this is by far the most detailed and interesting description of this assembly that we have seen.

Now we can see fine detail, one thing which surprises me is that the air feed and relief valve arrangements look quite 'chunky' compared to say the fixing bosses or the pocket milling.

djos
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Re: F1 Pneumatic Valve Spring, a closer look

Post by djos » Thu Sep 15, 2016 9:10 am

Amazing Brian, just stunning engineering, thank you for sharing this! =D>
The impossible often has a kind of integrity which the merely improbable lacks.

gruntguru
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Re: F1 Pneumatic Valve Spring, a closer look

Post by gruntguru » Thu Sep 15, 2016 11:29 am

Brian Coat wrote:Thank you, Brian.

I think this is by far the most detailed and interesting description of this assembly that we have seen.

Now we can see fine detail, one thing which surprises me is that the air feed and relief valve arrangements look quite 'chunky' compared to say the fixing bosses or the pocket milling.
I thought the same thing. Probably due to those functions (increasing or decreasing the operating pressure) being long term relative to the speed of the central mechanism.
Last edited by gruntguru on Sat Sep 17, 2016 3:48 am, edited 1 time in total.
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Brian.G
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Re: F1 Pneumatic Valve Spring, a closer look

Post by Brian.G » Thu Sep 15, 2016 2:43 pm

graham.reeds wrote:Nice.

Could you post a picture of it sat next to a coin for a size reference?
Graham, sure thing - here you go,

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I'll post up a few sizes and diameters later too, as well as the air drilling/passage map,

Brian,
If you think you cant, you wont, If you think you can, you will

Facts Only
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Re: F1 Pneumatic Valve Spring, a closer look

Post by Facts Only » Thu Sep 15, 2016 6:05 pm

Excellent work, really nice to see things out in the open to show people what really goes on in the engines.

On an asside, to me that looks like its been a typical Engineers "desk fiddling toy", well worn with lots of little scratches and dints where its been played with during long phone calls or while trying to work out a complex problem. The F1 part on my keyring looks like that.
"A pretentious quote taken out of context to make me look deep" - Some old racing driver

Brian.G
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Re: F1 Pneumatic Valve Spring, a closer look

Post by Brian.G » Thu Sep 15, 2016 6:28 pm

Facts Only wrote:Excellent work, really nice to see things out in the open to show people what really goes on in the engines.

On an asside, to me that looks like its been a typical Engineers "desk fiddling toy", well worn with lots of little scratches and dints where its been played with during long phone calls or while trying to work out a complex problem. The F1 part on my keyring looks like that.
Came directly out of a head 2 weeks ago - some flat surfaces are ground/lapped. I have been fiddling with it a bit during photoshoot mind you...

Brian,
If you think you cant, you wont, If you think you can, you will

godlameroso
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Re: F1 Pneumatic Valve Spring, a closer look

Post by godlameroso » Thu Sep 15, 2016 9:01 pm

Is the lash cap adjustable or would the rocker followers have the lash adjustment? or is lash controlled via pneumatics?
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johnny99
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Re: F1 Pneumatic Valve Spring, a closer look

Post by johnny99 » Thu Sep 15, 2016 9:38 pm

Well done Brian, awesome, you've chatting for a long time and you eventually got hold of one. I must say very well written too.

John

Brian Coat
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Re: F1 Pneumatic Valve Spring, a closer look

Post by Brian Coat » Thu Sep 15, 2016 9:45 pm

godlameroso wrote:Is the lash cap adjustable ...
Different height caps

godlameroso
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Re: F1 Pneumatic Valve Spring, a closer look

Post by godlameroso » Thu Sep 15, 2016 10:58 pm

Ahh, I see, thanks.
The height of cultivation is really nothing special. It is merely simplicity; the ability to express the utmost with the minimum. Mr.Lee

Facts Only
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Re: F1 Pneumatic Valve Spring, a closer look

Post by Facts Only » Fri Sep 16, 2016 7:21 am

Brian.G wrote:
Facts Only wrote:Excellent work, really nice to see things out in the open to show people what really goes on in the engines.

On an asside, to me that looks like its been a typical Engineers "desk fiddling toy", well worn with lots of little scratches and dints where its been played with during long phone calls or while trying to work out a complex problem. The F1 part on my keyring looks like that.
Came directly out of a head 2 weeks ago - some flat surfaces are ground/lapped. I have been fiddling with it a bit during photoshoot mind you...

Brian,
Really? Maybe its just the way the light is but the surfaces look rough to my eye. Lots of marks not in the direction of machining. Then again it is used and has been removed and dismantled.
"A pretentious quote taken out of context to make me look deep" - Some old racing driver

Brian Coat
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Re: F1 Pneumatic Valve Spring, a closer look

Post by Brian Coat » Sat Sep 17, 2016 2:34 pm

I think the marks might be very light. Brian has done a great job with the camera.

If the head was a rig test head or from a dyno engine involving a lot of build-strip-build work then the parts could have been 'handled' quite a bit .

riff_raff
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Re: F1 Pneumatic Valve Spring, a closer look

Post by riff_raff » Sun Sep 18, 2016 7:43 am

Seems strange that they use an aluminum piston and a steel bore sleeve. I can see the reason for using an aluminum piston, both in terms of reduced mass and heat transfer required from the gas compression heating occurring within the cylinder volume. Would be interesting to know why they use a steel sleeve in the aluminum cylinder housing. There are very durable coatings like Nikasil that can be applied to aluminum, which would seem to be a better option than using a separate steel liner in the aluminum housing. But I'm sure the guys designing the system knew what they were doing, and had a reason for making it like that.
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