The Secret Life Of Gas Springs

[@Infrared73]

Sir, I will not be skipping past 17m 28s of anything you put out there.

[@vinh7251]

Here here! But I will not despise those that do, merely pity this latest in what is probably a long line of poor life choices. Forgive them Tony for they know not what they do, the poor fools.

[@Mazaroth]

It'd be sacriledge towards the finer arts do even entertain the idea of skipping.

[@noname-zn2vm]

Why watch a video if skipping half of it wouldn't make a difference for you? I will never understand people that do that lol

[@D1g1tal_H1ppy]

yeah, why would i do that?

[@scottrs]

I mean you are not incorrect

[@PropGuru702]

They didn't use a stretchy spring because it could be stretched past its comfy zone and will inevitably damage the spring. By using a squeezy spring in the configuration they did, it prevents damage to the spring and instead it hits a dead stop when it is fully squeezed... (But I know you know that Tony 😜 I commented because al gore has no rhythm)

[@samroesch]

Ding ding ding!

[@FortyTwoBlades]

Additionally, the frame they used for the conversion acts as a spring guide to keep it aligned during the compression!

[@lzrjck69]

Also, safety. Tension spring snaps and flys avross the room when it breaks. Compression spring stays put when it snaps

[@yngndrw.]

Also, they had a load of spare wire and a CNC bender they wanted to play with.

[@FortyTwoBlades]

@@yngndrw. I get this is a joke, but in full seriousness the design is an old one going back to well before CNC benders existed.

[@integza]

This is one of those cases in which the math checks out, the physics checks out but I still can’t believe it works like that.

[@PeterBarnes2]

One thing that helps me (especially with Tony's end note) is to look at the volume the piston rod takes up as *being* a certain amount of work. Its average cross-sectional area entails a lack of (which means negative) force from pressure over area, and its length inside the piston volume is a length. Work = Force * Length. Or, more simply, Work = Pressure * Volume. That is, given an amount of Pressure, Volume entails Energy. As the volume is a negation (the rod serves to prevent air from occupying the space), you could imagine this like "negative work," but what you would then mean is Potential Energy: Work (done by a conservative force, which these pistons aren't because they're damped, but anyways) is the negative of the change in potential energy. When you push the piston in, you apply work, while the rod's increase in volume (that is, the volume strictly within the piston casing) occupies the energy of the gas it displaces. Relative to the the piston pushing outwards, this is a negative amount of work (it has gone inwards rather than outwards), and it also *is* an increase in potential energy (as the internal gas takes up the change in energy as change in pressure). But a Rocket Dude like yourself knows all that already. I just like the sound of my own typing. Displacing a fluid reminds me of buoyancy, which is the same but where the change in pressure is because of gravity. ...yeah, it's all still magic. Tomatoes are disgusting! (With the possible exception of the vtuber "Dokibird.")

[@jonathancard4466]

This and carburetors. There a a few things, mostly involving some kind of fluid, that makes me grateful I switched to Computer Science with some electrical. Parts of mechanical are black magic.

[@docpayce1]

The atmospheric pressure also pushes on the part of the piston outside of the cylinder. ❤❤❤

[@rodneymunsterman2287]

beet me to it😀

[@Beakerbite]

Yep. It's always there in all springs so should be included in the equation for working springs too. The reason we didn't is because it's negligible. There's also the friction force from the gland that you have to overcome and it should be considered as well if you were to start making springs commercially.

[@xl0xl0xl0]

@@rodneymunsterman2287 Would be cool if Tony welded an air connector to the hole and pressurized it to different pressures to demonstrate how the force changes with pressure. At Easy 15 extra minutes of content.

[@RiccBallard]

Well that sounds better than mine --> Magic! lol 😁

[@sihark]

exactly this

[@kevinjohansen8149]

I don't know if anyone has addressed this in the comments, but the gas spring is crimped and welded together with no visible port to charge the gas. It's pretty interesting process. They put the gas springs in a sealed chamber, pressurize the outside of the spring and the gas pressure goes past the seal on the rod because the lip is only pointing one direction. The gas goes past the lip seal into the spring to some equalizing pressure slightly lower than the outside pressure. The chamber is depressurized, take the spring out and they are charged. Our local supplier has some stocked charged very low,and they can increase the charge as desired by an application.

[@matthewjenkins914]

Very interesting, thank u for sharing

[@ellomirza]

It’s crazy what it takes to make things that are $10 on Amazon.

[@larryward1082]

I figured out how they did that long time ago Asian gas nitrogen gas not Asian to recharge of cylinders it works

[@trollmcclure1884]

There is a port. I took mine to a guy who added some pressure when I got myself a heavy trunk spoiler. He also said that decreasing the pressure would be much harder or impossible. BTW I got rid of the stupid spoiler last year. It was pushing the car down like 200 pounds and decreasing my mileage. I dont drive on the very edge 99.9% of the time so it didnt make sense

[@koenth2359]

​@@trollmcclure1884Yep, that's why its called a spoiler. A fuel spoiler

[@davidbaker308]

I was trying to fast forward to 17:28 but there was a constant force pushing back on my fast forward finger. You did it again.

[@bpc23]

"You'll notice all these springs are different." [moves duplicate off camera] Classic! Tony, you're the best!

[@brianhaygood183]

The "See my video on cylinders" gag took an admirable amount of effort, though. 10:06.

[@thedanishfabricator9334]

i was watching, it waiting lol

[@koenth2359]

The timing of that was brilliant!

[@jonathansimon3972]

There's 14.7 psi on both sides of the piston but now that you've drilled a hole in the side. you've now turned the entire world around it into a giant gas spring, so now there's 14.7 psi pushing on the end of the rod also! Congratulations you've now restored balance to the world, and that gas spring.

[@animusfoxx6965]

Kind of. You could close that hole though, and it would still not start moving. It's not that the air inside the piston and outside it are connected, that's incidental. The important part is that the pressure is the same inside and out. Semantics, I know... but the part where you said the entire world becomes the gas spring wasn't quite right. I mean it is and it isn't, because you could say it's a 0lb gas spring, but then it's not really a spring at all any more is it

[@patrickmorse7549]

If you charged the inside of the sealed piston with 500 psi and then put the entire piston assembly into a pressure tank at 500 PSI the piston would no longer provide any force to the end of the rod to automatically extend it because the force on the end of the rod would balance out the forces produced on the piston. Very similar to venting the cylinder to atmosphere.

[@evgenysavelev837]

I was going to comment the same as OP. But answering the "close the hole" question: at this point, ignoring internal friction, this will turn into a spring that tries to hold the position at which the hole was plugged. Compressing the assembly will increase the pressure inside, creating restoring force, extending will reduce the pressure inside, creating an opposite sign restoring force.

[@TildaAzrisk]

​​@@animusfoxx6965 In other words 0 psi relative to ambient. Could be a a 14.7 psi gas spring if the entire cylender is sealed and then thken to space where ambient pressure is 0 psi. In fact, if you had piston rod made of a material not affected by gravity, and that piston is long enough to have one side on the ground leveland the other side in space. Assuming 14.7 psi at ground level, then... hang on... Did i just make a space boat the floats on the atmosphere via boyancy? I think I did. Oops. Um... The demo I was making just floated away. Apparently a material unaffect by gravity is someing that you have to anchor to the grould, regardless of size. My experement is someone elses problem now, as I have no Idea how deal with the probem I just created. I really need to be more careful with how I run thought experements. My experement went very wrong moderately quickly.

[@alannull3497]

1st, I think your right. 2nd, and Most important question, Can the entire process be reversed if a vacuum were applied to the drilled hole. Would it then be a "constant pressure retraction spring"?

[@ChrisBLong]

For years, every time I closed the boot (trunk) of my car, I've thought 'I must look up how those gas struts work' but then I always forgot about it, until the next time. Finally, I know! Thank you.

[@pmcgee003]

Every time I open the boot of my car, I've thought the same thing, 'cos it immediately or at a random delay falls down and amputates another finger.

[@atlantajunglepythons1744]

I replaced my trunk and hood struts. The opening pressure is greater than the closing pressure just enough. I believe it’s technically fantabulous™ a term of art….

[@scarpadog155]

You did look it up, or at least wondered across it. It was fate.

[@ctrlaltdebug]

@@pmcgee003 You need to replace the gas struts. Some of the magic leaked out.

[@nathanparker5378]

My dad was a mechanic, but he never had the patience to explain things to me, so I went off and became a biologist. Thanks for being my internet dad, This Old Tony.

[@SOHCHEAD]

This reminds me of one of the Mad Max characters in the newer saga. The "Organic Mechanic", that could be you! (Not the actual character, just the word play)*

[@pivotfever]

I think he just wanted to save you the trouble of hating an engineer

[@AlanShortySwanson]

OUR internet dad. ;)

[@koenth2359]

I am a dad of 3, they never showed much interest in my physics explanations, and I don't want to push it through their throats. My biggest fear is that I will read a comment like that about me.😂

[@kylesebring]

As a son with a father whos the exact same, sounds like you also didnt have the patience to try to understand him, which admittedly is hard for a kid to do, but necessary if you want to learn someones knowledge.

[@thanatos454]

"Be careful. Don't stupid." needs to be on some merch.

[@zygmuntthecacaokakistocrat6589]

& on all workshop machinery.

[@calvinculpalt]

I'd buy it!

[@tonyh.2126]

Absolutely! I wouldn't be able to get to my wallet fast enough!

[@jamesrivettcarnac]

That be good merch

[@Orbitter1]

Yeah, I'd deff buy a t-shirt and stickers!

[@jasonodom7396]

When I was a kid all the old wooden screen doors had a long skinny stretchey spring. I haven't seen one in decades now, but ill never forget the sound of those springs stretching and rubbing against the door and then the sound of the door slamming back against the door frame as they closed.

[@Elmojomo]

I just heard that sound in my mind. How did you do that? lol

[@keithvers569]

That’s a perco spring

[@suamme1]

I always loved the spring shaped groove that eventually showed up in the door itself. It told you a lot about the age or amount of activity the door has seen.

[@barretthoward6042]

This old tony makes me feel like a kid again. 11 years old and home from school. It's raining so I can't go outside. Mom put PBS on the TV so I would stop bothering her about my being bored. The reading rainbow just started, and normally I'd scoff at the idea of an " educational adventure" but this time is different. I want that. Several hours later I can't stop talking at dinner about how much work goes into building a dam, or what airline pilots actually do. Having for the first time enjoyed learning something. This old tony thank you for making me want to learn again.

[@johnathanscopazzi7203]

Born in 95' I share this sentiment. Learn from (your elders) whoever will teach, if you are willing to listen. Stories are human history experiencing itself.

[@Zogg1281]

The average classroom is normally the worst place in the world to try to learn things!!! Years of geography at school and quite a bit of work on rivers and how they change over time....... basically taught me nothing. Fast forward to a beach when I'm working as an outdoor instructor and my boss (used to be a teacher) uses his umbrella to scratch a "river" into the sand..... I learnt about how rivers meander, erode the outside of bends, deposit material on the inside of the bend, and eventually break through a new channel and form an oxbow lake........ in under 10 years I learnt more then I did in the whole time I was at school!!!! Forcing children to "learn" information so that they get good test and exam results just doesn't work for a very large percentage of children and we need to learn a new way to pass knowledge on to children

[@Cyromantik]

​@@Zogg1281 Modern education wants to create a workforce, actual elucidation takes a back seat to this aim. I'm not excusing it. In fact I work in education and this is something I fight against, albeit not too stridently, as I also need to pay the rent and eat.

[@jasi5534]

Growing up without a father figure, yes to all of this above. ❤😅

[@ericsaresky6246]

I’ve been looking for Subscribe brand pneumatic cylinders for years and TOT has one!

[@ncstudio333]

I miss the days when TOT was still new to me and I had like 200 new videos still left to go through 😢

[@ydrts_915]

I feel you, but I go through those regardless:)

[@davidsiddle4678]

Those were great days...

[@brickabrack_cat]

As my uncle says on a fairly regular basis: “its time for electroshock therapy!”

[@Andrew_Fernie]

That I hadn't watched at least twice

[@anonymeister123]

I subbed awhile back when Adam Savage from Mythbusters shouted out the channel. Have not been disappointed.

[@rogerwilson7971]

I have a product that uses gas springs, I love the dampened movement, the constant force isn't an advantage. But understanding the simplicity of how this device maintains the constant force made my day. Thank you This Old Tony, love your humor too my friend!

[@Jpopnasty]

I am an engineer in injection molding and this video just solved a puzzle in my mind that was driving me nuts. I thought I knew a good bit about hydraulics (typical engineer) and I couldn’t understand why some cylinders on our machines would drift out (horizontal, no load on the rod) even though the control valve was in the closed position. I assumed it was the control valve leaking oil by the seals but changing the seals in the cylinder fixed the problem. It was just the sealed and pressurized system acting like these gas springs with blow by leaking around the worn seals? Incredible!

[@tomw86]

I'd have a look at what valve you are actually using in this application! You can get rid of this issue in the future by changing the drive for something that doesn't hold pressure in the system!

[@prestonseible3512]

I’ve been having this exact problem at work except with a hydraulic cylinder. Im confident the issue is bad cylinder seals but I still don’t understand why. Our cylinder drifts when there is pressure holding the cylinder retracted and the advance side of the cylinder is open to tank via the solenoid valve. So any pressure that leaks past seals should immediately drop to negligible pressure as it is now open to flow back the hydraulic tank. Any ideas?

[@michaellynch1018]

Yup, worked for a time doing electrical maintenance at a steel mill and my mechanic counterpart and I would see this pretty regularly. Easy to swap the valve out or bypass in the control scheme to double check, but not so easy to swap out a cylinder 😁

[@tsl7881]

Had a baler with hydraulic dampening cylinders that controlled the belt tension, all would look good till you stopped then the pressure/ tension would drop off... Bad piston seals, not the tension valve block assy.( an adjustable relief valve.. Its always good when cylinders leak out the ends, bad when it's an internal leak. Of course, it helps.to get a good diagram of what is going on.

[@BenG4]

@@prestonseible3512 That is weird, by advance side I assume you mean the base port? So you've got pressure on the rod side port, and you're venting the base port to tank? That should definitely stay retracted. Are there counterbalance valves on the cylinder? Depending on the applied pressure and pilot ratio that may not be enough to open the CBV, which leaves you with a displacement cylinder like the gas strut. If your retract pressure was really low and you had some significant tank pressure that could also do it.

[@isaackvasager9957]

As a former high school physics teacher, I never stopped to think of the wonderful physics in a simple machine like this. Wish I would have thought of this as an example to use in teaching these concepts. Thanks for the awesome video!

[@Youtuber-k2p]

I taught science to first year high school kids, 12 & 13 yr olds, we “did” pressure. I started that week long lesson with big letters on the chalk board: that there is NO SUCH THING AS SUCKING. There is only pressure differentials. Remember those little boxes of fruit juice, you didn’t suck on them to make the juice come out, you created a low pressure area in your mouth and the external air pressure, 14.7 psi, pushed the juice into your mouth as the juice got in the way of the pressures trying to equalise! I gave a blood sample at the dr the other day, the nurse inserted the needle and then pushed a little cylinder into the hypodermic cylinder, no withdrawing of a plunger but the blood flowed! I said, thinking air pressure at work, “how does that work”, she said “there’s a vacuum inside” the little cylinder receiving the blood. I said, “mmm, no if there was it would implode but there is a low pressure in there and the blood pressure in my body was sufficient to overcome that small amount of pressure and the cylinder filled with blood”. 😮😅

[@crfadv]

@@KZbinr-k2p I disagree. "sucking" is an action of creating area of low pressure (creating pressure differentials), so "sucking" does exist. But, yeah, nice intro to a lesson! you need to catch attention of kids somehow

[@q.e.d.9112]

@@KZbinr-k2p I can’t imagine the ribaldry if I had written “There’s no such thing as sucking” in front of a class of teenagers.

[@MikkoRantalainen]

@@crfadv Yes, you create low pressure gas by sucking gas and then air pressure of atmosphere moves the liquid because of pressure. And when you create low pressure gas, you're basically extracting gas molecules from one end and air pressure remaining in the low pressure container pushes the remaining air towards you. This is also why creating perfect vacuum is practically impossible: you're trying to suck air from one end and to get few remaining molecules from near vacuum, you would now need some force pushing those molecules towards the suction hole but there may not be enough pressure near vacuum. Brownian motion slowly moves molecules around but that's a slow process but still the best you can do when you're trying to create near vacuum space.

[@sirtra]

​@@KZbinr-k2pwhy is "did" in quotation marks?

[@motoxjosh29]

no explained this to a 15 year mechanical engineer so simply. love your channel!! cant believe its as simple as that groove that make it all work....

[@duketogo100]

that "seam" is actually a groove that is tuned to get a force profile for the start and end of the stroke. On vehicles that use these struts to hold hatch doors open, that force curve is dialed in to make sure the door doesn't slam closed towards the full compression end of the stroke and also makes sure it doesn't shake too much while nearing the full extension part of the stroke. It is also important to make sure the door/hatch doesn't open too quickly and slap you in the face. Some companies care about this more than others, but customers sure notice when it becomes an issue for them.

[@mikew1547]

Exactly. The cross-sectional area of the groove varies along the length of the tube to slow down the piston so that the hatch comes to a nice smooth stop. This is one of the "tricks" of the engineering design - getting the piston speed tuned so that it opens fast enough to get out of your way but not so fast that you get knocked over by it. Other engineering compromises in the gas spring & hatch system design are: getting the opened hatch height adjusted so that tall people don't walk into it while short people can still reach it to close it, getting the geometry dialed in so that the mechanical advantages of pulling on the end of the hatch is just enough to overcome the gas spring force (for example, a typical person will pull down with 15# of force but this needs to overcome the 120 to 200# force of the gas spring), and balancing cold weather performance (hatch won't open by itself or stay open) versus hot weather performance (it takes too much force to close the hatch).

[@mikoajp.5890]

My OEM fifth door gas springs lost pressure after getting old enough. I got a locally manufactured replacement, same everything, a five minute task of replacing the dead originals. You've perfectly explained why after switching to replacements the rear hatch opened with a violent stop at the end, shaking the whole door!

[@billallen275]

That is a neat idea. Elegant. Just those pesky rod seals, but it's amazing tgey last like they do. ​@mikew1547

[@natalie5947]

I spent the whole video thinking the inside had to be relatively complex. Using a regular spring inside to meter gas flow or something. When you showed how they actually worked, my reaction was literally "you've got to be kidding me!" Brilliant video as always. Thanks for posting.

[@eduardogm8236]

Exactly same thing here. Tot always make me feel like an idiot.

[@dipi71]

I'm still baffled which kind of seal would withstand a pressure difference of hundreds of psi around a movable piston rod for months or years. Is it just rubber or silicon or teflon or what?

[@mikemcleroy8265]

@@dipi71probably a proprietary secret 😂

[@mikew1547]

@@dipi71 Special rubber formula that is resistant to chemicals, oils, heat, UV, etc. Some manufacturers use a lip seal, that lets pressure slip by in one direction (from the outside in, so that the gas spring can be charged) but won't let pressure by in the other direction (as the pressure increases, so too does the force holding the seal against the piston rod.) The company I used to work for used a rubber ring with 3 "lobes" on it; as the pressure inside the cylinder increases it compresses the rubber so the lobes push harder against the cylinder walls and the piston rod.

[@AlanShortySwanson]

How do people come up with stuff like this?!

[@athhud]

Understanding that the rod is essentially a piston and that a sealed piston isn’t even needed in a single-acting cylinder opens up a whole new world of understanding when it comes to hydraulic/pneumatic cylinders and air springs. It is very obvious once you sit down and do the math, but a lot of guys struggle with wrapping their heads around the concept out in the field. You can also trip them up pretty bad with a gravity-assisted cylinder being fed by a single hydraulic line. When it starts leaking down they will swear to you that the piston seal is leaking. After you pull it apart and show them that the “piston” (rod guide) has obviously never been “sealed” based on its inherent design, you can get a pretty good chuckle as you wait for the gears in their head to start meshing. The chuckle is a lot better than the feeling of dread that comes with having to rebuild the leaking control valves that are buried somewhere extremely inconvenient.

[@igorproskochilo9805]

Exactly! the “piston” is only needed as rod guide, and to create more resistance that help to dampen very quick compression, as air need more time to pass thru that small slit so pressure is raised in the opposite chamber

[@robertberndes7878]

Exactly 🎉🎉🎉🎉👍👍👍

[@dmagliola]

Sir, this is an absolute masterclass in explaining. That moment at 17:30, where you just hold the drill for just enough time to let everything sink in and let the viewer figure it out by themselves... Absolute gold.

[@edwardhugus2772]

You made it the WHOLE WAY through the video without breaking the Wife's Glass Flour jar! I AM impressed! Good to hear from you, old friend. Thanks for the smile.

[@gcewing]

Wife: "Why have you drilled a hole in my flour jar and pressurised it to 90psi?" TOT: "Er... ah... the flour keeps longer that way!"

[@criggie]

Did you not notice the series of stunt jars? The body double that did the dangerous scenes so the Talent Jar could avoid the risk of shattering ??

[@mightyluv]

Your video reminded me of the days when I was broke but had access to metalworking machinery and materials; I designed and built a backcountry water pump that would discharge an equal volume of water on both push and pull strokes based on the piston rod displacement. It was a good mental challenge at the time, and super useful when I was out hiking. By contrast, I’m now financially comfy, but no longer have access to that equipment. I really miss those days.

[@andreasornerfors3674]

Not realy relevant to the subject in the video, but I have to extend my deepest thanks to you Tony. Your videos made me interested in machining, and after a few years working as a CNC-grinder I realised that precision was my thing. Last week I graduated as a measurement technician (in the hometown of legendary C. E. Johansson) and this journey began with your videos. Again, thank you!

[@K1lostream]

I was inspired by Tony’s video on steel reinforced concrete and have recently embarked upon a career as a central tunnel support on the new Victoria line.

[@nickskerrett5240]

Tony is probably busy with his groupies for the next few weeks so just in case he doesn't see this comment. Well done! That's great news and congratulations!

[@shawngoldsberry747]

Good job, very Impressive, please try to inspire others.

[@Niki_Parvanov]

That sounds awesome! Good for you 🎉

[@dr.hinneredv932]

Wow!

[@thesuit4820]

Hypothesis re storm doors: when a compression spring bottoms out the load goes to something stronger. Tension springs stretch out and then snap (without even more complex extra stuff).

[@triple7988]

When all else fails, compress the problem! Smaller problems = smaller solutions.

[@clarencegreen3071]

The compression spring arrangement has a definite, fixed amount that it can extend. A simple extension spring would have no such limit. (My guess.)

[@ivladjoll7410]

the spring will stop compressing causing a hard stop for the door. this means the force will gradually increase then stop the door. If it was tension spring you would not have the hard stop and the door could keep going into who knows what.

[@scrotymcboogerballs6452]

​@clarencegreen3071 it's that and also the defined space constraints with the swing of the door and finally that you can't overextend a compression spring, once it's fully smooshed that's it, it won't get more smooshed, it has a defined "max smoosh strength" It's also a captured spring, if it breaks it's trapped in the contraption and won't fly off and blast you in the face when it's doing it's thing Those are my informed opinions on the matter having met many door springs

[@peterjensen6844]

This.

[@thaostrich]

I've been a Maintenance Tech for nearly 10 years and did not know how they worked. I knew the concept of force loss in a pneumatic cylinder due to the rod on one end, but never applied that logic to a sealed system. Thanks, Tony!

[@ChrisHallas]

And I was just about to go to bed...

[@f0x52]

yep...

[@Tvngsten]

I have to wake up so early tomorrow, but well, TOT uploaded, no sleep for now.

[@TheProjectHavoc]

Yeah dude, me too 😂

[@mullrump2]

Same

[@Kheper1]

Same

[@jimmyboy9883]

“This is a cylinder, if I’ve lost you already, watch my video on cylinders” 😂

[@chemicalcorrosion]

😂this is definitely an advanced course for someone who can’t grasp the concept of the cylinder 😂😂

[@barefootalien]

My guess for the compression spring converted to act like a tension spring is that they needed a strict limit to the range of motion. A tension spring only has that once the entire spring has unraveled and reached its fullest extension as a _cable_ but realistically it'll just break before that as it develops kinks (because it's twisted), plus that would be a _long_ distance for a spring with that many turns. In other words, a limited-travel extension spring needs either a very high spring rate, or a very short useful travel before it hits plastic deformation. This could be solved with something similar to a "droop limiter" if you're familiar with off-road vehicles, but that would add complexity anyway and might not get the exact properties they were looking for. The way they did it is _slightly_ more complex, but think of it like a bump stop in car suspension. In normal operation the spring will absorb light loads smoothly, but in an extreme case (like a storm blowing a cellar door hard open, perhaps?) it'll just slam into the maximum length provided by the much thicker wires forming the extension stop.

[@BlueJay137]

After you drilled the hole in the gas spring, you can see that there's nothing inside. So obviously you would know that the piston wont move. But when the gas spring is fully enclosed, there's no way to see inside; thus the intention of the device activates and pushes with constant* force. Good video! Learned a lot!

[@Mark-px3rq]

😂

[@tridium-go6hw]

The Shroedinger Uncertainty Principle - of course!

[@Skyra_0]

🤣

[@mailleweaver]

It runs on faith. "Faith is the evidence of things not seen, the essence of what we hope for." Once you can see there's nothing inside, there's no longer anything unseen, so the faith it runs on can no longer exist and it stops working. That's also the obvious reason why his glass one didn't work even after he drilled a hole in it. We could see into it the whole time.

[@WarttHog]

​@@mailleweaverWoah, wasn't expecting to see a quote from Hebrews in the comments of a TOT video! But not gunna lie, the first thing that came to mind was DC Talk. (The 90s Christian band, not TOT talking about welders.)

[@makerspace533]

Fun fact: It would appear that a coil spring works on forces bending the spring material, but really it is twisting the material. A coil spring is just a torsion spring wrapped around a helix.

[@daveh188]

My old car Valiant (1970s) had a long bar that twisted (torsion bar) rather than coil springs. Same result.

[@jforrestal365]

And a torsion spring actually bends the material

[@trespyyy]

1:50 Secretly changing the colour of the screwdriver you're holding is genuinely a diabolical mindf*ck.

[@thedevilinthecircuit1414]

The first one (clear with red stripes) is a standard flat blade driver. The all-clear handle is Phillips. And Now You Know! Without even looking at the pokey end of the tool.

[@colerobison6916]

24:20 The piston rod isn't pushing out anymore because there is an equal pressure force acting on each end of the rod. 1.8 lbs pushing out and 1.8 lbs pushing in. Both ends are at atmospheric pressure. Equilibrium :)

[@Mark-px3rq]

Right, the key point is the pressure is pushing in all the way at the tip of the rod outside the cylinder. That’s where the equilibrium of forces is achieved - the sum of the forces acting on the whole piston. When the sealed area is pressurised, the force on the tip of the piston is still there, but not equal to the opposing force from the unbalanced area inside at a higher pressure

[@codex202]

i thought it was that is *is* but the friction is too high for it to be noticeable(?)

[@gorak9000]

But what if the end of the rod has a tapered point on it, so the atmospheric pressure can't push in the direction of the rod anymore, but can only push perpendicular to the surface, which only partly pushes in the direction of the rod?? Then what??

[@yarbles_]

The force is only partly in the right direction but it's bigger due to the larger surface area of the point. It will be the same whatever shape the end is.

[@simno345]

@@gorak9000 The force perpendicular to the surface of the taper (cone) can be decomposed into a force perpendicular to the rod, and a force along the axis of the rod. The force perpendicular to the rod cancels out (it's equal all around the rod). The force along the axis of the rod is just equal to the force that would applied to the end of the rod anyway. The axial force at any one point on the cone is less than on a flat end, but the surface area is much greater.

[@ObscuraDeCapra]

On the storm door springs, a compression spring is used as a way to keep the spring from being completely wrecked if the wind happened to catch it. If wind grabs the door and slaps it open an extension spring would likely be stretched beyond its capacity. The type you're showing here is often called a "wind chain" for just that reason. A compression spring, of course, doesn't have that problem. The other thing it does is provide a hard limit to how far the door can travel. An extension spring could allow it to slam against whatever it's next to. Like your siding. Or a window. The compression spring reaches the end of travel and just STOPS. Unless it's really ridiculous wind, of course, then it just rips the chain apart and flies along with the rest of your house halfway across the county. Source: Sold doors for a couple of years. In Texas.

[@CDCI3]

**Wind proceeds to max out the spring and rip the screws out of the wall just to assert dominance**

[@AlexanderBurgers]

also seen variants with a pull spring and just.. more chain in parallel. When the pull spring reaches whatever the desginer deemed full extension the chain in parallel goes taut and takes over whatever extra force is applied beyond that point. So yeah, definitely it's to give the whole thing a hard stop at the end of a pre-determined amount of spring travel.

[@gorak9000]

Then the wind rips the screws out holding the spring to the door, because they've reduced the thickness of the door to a point where it's still technically a door, it has no strength anymore. So it's definitely better to have a door with ripped out stripped out screw holes than a slightly stretched pully spring??

[@firstmkb]

You brought up a memory from LONG ago, when I was a kid and screen doors had those.

[@everettplummer9725]

I work in tool & die. We put flats on long rods in cylinders, to pass air. The tolerances are too close for the dies to move freely, otherwise. Made a set of four progressive dies, for thin plastic sheets. The dies are ground to size, and according to the material thickness, holes in the plate, are made oversize for clearance. The thicker, the more clearance is necessary. So the dies are attached to the rods, and they go through tubes. And attached to die sets, with guides, that have bearings that help hold everything in-line, dowel pins, springs and strpper bolts, keep everything lined up. Engine timing gears, often get vent holes, to quiet them down. Thanks for the idea, they won't know what hit them.

[@wvmotorider9723]

Screen door spring uses a compression spring as an extension spring so that when it reaches its travel limit it creates a hard stop by becoming coil-bound rather than a normal extension spring which would continue to extend, eventually reaching its elastic yield point and stretching.

[@louchedecay7922]

This is it. You can make a device simpler by eliminating the need to engineer a positive stop somewhere else in the assembly. They're usually called drawbar springs.

[@StefanReich]

Yep. Figured this out too. Feel smart now

[@Zardwark]

I think what happened is when you drilled the hole you let the springesium out. If you look on the floor and find it, pack it back in where it came from the gas strut will work again. It's sort of the same as that grey gas they put in electronic components, if it gets out, it stops working, but it's bloody hard to get it back into an 8 pin IC. so most people just junk it and buy a new one.

[@morrisgetman9827]

I just had one of the most pronounce Eureka moments in my life. Seriously. I had assumptions, but I felt they were wrong, exactly becasuse they did not explain the constant force feature. Thank you so much!

[@RonsealBrown]

Tony, the 3rd type of spring uses variable winding pitch and/or variable thickness to achieve constant force along its range of motion. The maths behind them is insane because you can't just choose to compress one part at a time and the spring rate is constantly variable along the length so you can't just calculate it as stage 1, then stage 2 etc. I mean, you can for estimations. But not for science.

[@barcodenosebleed5485]

Equally insane are vari-mu vacuum tubes.

[@firstmkb]

Is that why retainer springs for AA batteries start with a large diameter coil and reduce over the length of the spring to a smaller diameter?

[@RonsealBrown]

I see your thinking, but not quite. The springs you have described are called conical springs. They have 2 major applications: small form factor and sideways stability. Obviously electronics need a small form factor. Conical springs nest at just one coil diameter thick when compressed! Also people jam batteries in carelessly, particularly in something like a children's toy. Conical springs are less likely to get jammed up and kinked sideways than a narrow, long coil spring. Constant force on a spring is more important for longer distances of spring travel and bigger forces than for AA batteries.

[@RonsealBrown]

That's ok :) well done on your knowledge. You are commenting on a video where Tony kindly and carefully explains how pressure = force/area, and that equations can be rearranged. To viewers benefitting from that explanation, integrals may well seem like insane maths! And they should rightly feel proud of themselves if they try looking into it further. I'm know I'm proud of them. Have a beautiful day.

[@markterribile6948]

​​@user-yb5cn3np5q But working on them can drive you insane!

[@kenmohler4081]

How is it that the KZbin algorithm didn’t put your work in front of me before, Old Tony? This one was right down my alley. Thank you for your insight, humor, and presentation. But now I have a lot of stuff to watch to catch up on. Thanks a lot, new friend. I think!

[@EvenTheDogAgrees]

Oh, are you in for a treat! This guy's videos are always a blast! Enjoy, man. :)

[@opendstudio7141]

Another happy time traveler! Welcome to the future past.

[@clahck8552]

Let the binge begin! Well worth it!!

[@tomasclasson]

remember to eat and sleep, occasionally...

[@AlanShortySwanson]

Lucky!!!

[@guhammer261]

Thank you! Thank you! Thank you! You ARE the most entertaining teacher I know. I probably could ramble on for another dozens of lines or so... talking about the enjoyment of learning if it is served the right way and so on... but you get my poi

[@Makes-and-Mods]

I don't know how you get my inside tears to be outside tears Thisold but every video gets me leaking and laughing until my knee springs get sprung. You are a gem Mr. Tony. A gem.

[@saradeanna]

Hi Tony, Porsche makes (or made) a hydraulic for their convertibles that has a cylinder with a gland end on both ends and a piston rod coming out of both ends with the piston in the middle. The rod is hollow and each end of the rod has a hydraulic port which send fluid down the center of the rod and out of vent holes near the piston - on either side of the piston. It's double acting and has equal force in both directions.

[@ChrisAWare]

I unfortunately didn't get to watch this when it was uploaded, so i know my comment will just be buried and you may never see this. But you just answered an issue we had with a hydraulic cylinder that my shop built for rather large steel manufacturing company that commissioned some 30k# lift cylinders from us. They gave us drawings their "engineers." They called for single acting, 5 inch bore, 2 inch rod, but the piston had a hole in it. I mentioned to my boss that i didn't think they would lift what they want with the hole, but i couldn't explain a reason. The cylinders came back, they wouldn't lift. Your illustration at 19:00 finally gave me the answer I needed. I didn't think of it as the top side of the piston counter acting the force at the bottom, but my brain was telling me that they were only getting the lifting power equal to the 2 inch rod. Once we replaced the piston with a solid one and a seal, they had their lifting power (5" at 2500psi). I just knew that there was a reason behind most single acting cylinders being sealed at the piston properly, or in the case of telescopic cylinders, the "rods" being only slightly smaller than the bore to get the power they produce. Thanks TOT!

[@crutchgecko]

Magnet you just invented the "variable force, constant force spring" ? Just charge it up with the right psi for the current situation. I can't see any use for it at the moment but someone someday might need this!

[@bretonkyle]

Venting that bonus gas spring sure is one way to make it constant force! ;)

[@onlyadog]

Going through a pneumatics course right now so a lot of the info that was in this video is still fresh in my mind, and despite that the moment you put the differing extention and retraction forces on screen and was about to explain the constant force aspect of the spring it just *clicked* in my mind. Felt like a purely magical moment and I haven't felt that in a while! Also the reason the cylinder doesnt extend is because the 14.7 psi of air pressure is acting both on the inside and outside of the cylinder fully since its also able to act on the rod diameter so the forces cancel out. Wonderful video sir!

[@garymills6020]

....less the diameter of the rod, and the force isn't enough to over power the friction of the seal in the cylinder.

[@DragonJujotu]

To clarify, the 14.7 psi is also acting on the end of the piston rod that sticks out of the tube, so there is no difference in cross-section.

[@GoBO207]

So simple in math, so simple in practice, so hard to actually intuitively get from the start. Love your work TOT!

[@NoIce33]

There is atmosphere pushing the rod in with the same force. Great explanation in general; learnt a lot. Thanks!

[@Luke-mp3lj]

Beat me to it, darn 😂

[@AndyHullMcPenguin]

For a few bonus points, what will happen if you seal the hole.

[@HipperTea]

Would it not be a different force? The atmosphere is pushing on the piston with the same PRESSURE in both directions, so for P = F/A on both sides then the force has to be less because the area is less on the piston side. I'm not trying to correct you. Genuinely asking.

[@ajbh2o]

​@@AndyHullMcPenguin no reseal the hole then bring it to the top of a mountain. 😁

[@klikkolee]

@@HipperTea The "P" of that equation isn't the only thing that's the same. The "A" is too. It takes calculus to prove it, but if you have an object immersed in a fluid (gases are fluids) of constant pressure, there will be no net force (and no net torque) on the object, no matter the shape of the object. In a working gas spring, part of the rod is exposed to atmospheric pressure, and the other part is exposed to the charge gas, which is a different pressure, so this doesn't apply to the working spring. The actual atmosphere is not constant pressure. The biggest source of non-constancy is gravity, which causes pressure to decrease with height, and that particular non-constancy creates the buoyant force.

[@jc5c515]

I was watching a film when I received the notification, I hit the pause to watch this video, because of priorities 😊

[@stormdrifter7904]

I hope the rest of the cinema didn’t mind

[@jc5c515]

@@stormdrifter7904 lol 😂

[@gorak9000]

@@stormdrifter7904 That'd be the best day ever, you're in the cinema, in the middle of a "film", and some dude stands up and proclaims "NEW TOT VIDEO IS OUT" and the theater stops the "film" and puts TOT on the big screen! It's good to have dreams...

[@baraBober]

Tony, your video made me experiment, and I'm having doubts. It seems that the size of the piston does not affect the force IF there's no seal around the piston. The only thing that does affect the force is the girth of the rod. The piston there serves 2 purposes: 1) slows down the air transition from one side of the cylinder to another. 2) keeps the rod centered to prevent damage to seals. Don't worry, you're still my favorite KZbinr

[@billbates6395]

Why didn't they teach it like this in school? It wouldn't have taken me almost 50 years to learn it this simply! Damn it! Thanks!

[@recoilrob324]

Because it takes intelligence to explain a difficult theory in simple terms. This is actually a gift that not many people who are in the teaching business possess. The 'Professional Teacher' is said to be able to teach ANY subject without experience....which doesn't work well at all when someone asks a question that's not covered in the teaching manual. A truly inspirational teacher can change a student's life by lighting up parts of their brain that laid dormant by challenging and explaining simple concepts that work together to do seemingly miraculous things. If you had such a teacher in your life...consider yourself lucky as many don't get to experience this.

[@petergerdes1094]

It's not a capability issue. Many teachers absolutely have the capability. It's because learning, like sex, is much more enjoyable when you do it by choice. Teaching like this only works when the person wants to learn and is willing to actively think about what is being said. Unfortunately, the incentives in school discourage tracking out everyone who isn't genuinely interested and if you need to get students who are diligent (and maybe even smart) but lack interest or find thinking about the subject adversive then a degree of rote learning is the only thing that works.

[@Danger_mouse]

TOT - Thank you my friend, I learnt something today! I've been a motor mechanic for over 40 years now, I must have changed hundreds of those gas strut units in my time... I never once assumed there was anything that clever going on inside them and would have been someone to jump in and 'correct' you on the whole Constant Force thing. I dips me hat 🧑‍🔧

[@Plons0Nard]

Since you asked : plug the hole you drilled, weld it if that is your way, then : sell it to a spaceship builder 😊 It will work fine in a vacuum as a gas spring. Cheers sir, and greetings from the Netherlands 🤝🏻👍🏻🇳🇱

[@pierrekin]

Mister @This Old Tony I really hope you read this. Your inside voice, respectful video titles and well produced yet still casual style is so refreshing and welcome on my feed. I can tell you also love to watch KZbin and I just want you to know that little spark of joy you get when your favourite creator uploads something, you’re that guy for me! ❤

[@sky173]

These videos always put a spring into my step! Thanks for sharing!

[@kellerbenjaminjames]

Each time I see a new vid from you I think I won't have time to watch it because I'm not a machinist and nothing you say has much to do with what I do for a living, but every time I watch the whole dang video. I love your sense of humor and it's cool to know how things work. Some of the machines I work on use these gas springs to hold things open. I never really thought about how it works I just figured it's pressurized and that's good enough for me. But... Knowing and assuming I knew how it worked were two different things and now I actually know. That's pretty cool.

[@PatrickHoodDaniel]

A simple explanation is always better than a complex argument. Well done!!

[@SuodesTzeos]

The two different screwdrivers are driving me crazy! 😂 ToT back at it again with the subtle jokes

[@firstmkb]

I started watching for that, then got distracted by “the learning.”

[@DrewskisBrews]

I wonder if it also helps him during editing. Sorting through 200 clips of a pair of hands on a steel workbench must be like sorting Philips head screws from stainless steel Philips head screws

[@patricksullivan9951]

Talk about Timely Old Tony, I just happen to be working on my 2nd Gen Toyota 4Runner, the hood piston struts! They died, sad! But now that I know everything I need to replace those springs, and how they work, NICE! Terrific Timing Tony!!! 😀

[@Drmcclung]

I love the subtle nod to Tim Hunkin in that title and thumbnail!

[@jimmybryan6760]

Thus why I'm hearing the reggae version of "Take Five" in my head while watching

[@scrolll_on]

I was looking for this comment!

[@BrianHoff04]

@@scrolll_on Why did the Brits do such a great job with TV shows regarding science & engineering? Our History Channel, Discovery Channel, PBS, and a few others tried, for a time, to truly help us understand.. all of that is gone. Thanks, Tony.. for trying to keep it going.

[@Drmcclung]

@@BrianHoff04 I've wanted to fly over and visit both the central London and southwold pier installations for ages.

[@treelineresearch3387]

@@Drmcclung Mr. Hunkin has a whole arcade called Novelty Automation, it's on my list of places to visit if I ever end up in the UK.

[@daffster13]

I literally get giddy when your new videos show up in my feed. Thank you sir

[@-IE_it_yourself]

i just thought it was an only video at first.

[@grumpyone5963]

Literally the best / most entertaining / most interesting thing you will see that day!🇬🇧

[@floraly88]

"you do that a couple of times while you acclimate to the terror....." bro im cryin. This is just the best line and caught me off guard.

[@BTGDelta]

I'd say it's because the same (atmospheric) pressure applies to the other end of the rod, the one that is stuck outside the whole time. This brings the forces to an equilibrium.

[@SmokeStackZA]

Mind blown! Realise that the piston's job is nothing more than keeping the piston rod centred and facilitating the dampening with it's small hole. If you were to make the hole bigger and bigger to the extreme where there's no piston left, the math starts only looking at the piston rod, which is the alternate way of explaining the working. The gas inside the piston tries to push the rod out (imangine no piston and the gas pushing at the end of the rod, as the piston gets pushed on from both sides, except for the area of the end of the rod). Atmospheric pressure is trying to push the rod back in. Thats the reason the rod's not moving as atmospheric pressure are both inside and out. Thanks TOT. I love many youtubers but I love you most. ❤

[@beanMosheen]

Yeah, I made a similar comment without seeing yours. The piston surface area isn't part of the force at all. It's the rod acting as a compressor.

[@EvanZalys]

Yeah - I found TOT’s explanation substantially more difficult to understand than just saying that “the volumetric change in the cylinder is small due to the displacement from the rod. P_0 V_0 = P_1 V_1, so if V doesn’t change much, P won’t change much, and so the force doesn’t change much.”

[@EvanZalys]

And yes, the piston is not a piston at all but just a guide bushing.

[@brianstenger154]

So the piston acts like a piston only for the dampening force by allowing controlled transfer of gas from one side to the other through the hole in demo and the groove in strut

[@shawn2295]

An extension spring would stretch if over extended, leading to the door slamming into the wall. The "Storm door chain stop" limits the amount of travel while the compression spring absorbs the shock, if the door were to open too far too fast. Love ya TOT!

[@joenelson]

Tony, I don't know how you did it but each of your videos of this year have hit EXACTLY when I needed it. Not the subjects of the videos, I can't seem to put any of that to use but the fact that your humor lightens my day at the right time, every time has to be noted. If only everything in my life had your timing. Keep it up!

[@scottsmall9898]

Greatest start to any weekend, TOT put out a new video!!! Everyone stop whatever you are doing and get ready to learn and more than likely smile or laugh a few times.

[@Gregorius421]

Thanks to this video, I was reminded me to watch an explanation of gas springs in 3 minutes. Now I know how it works, fascinating.

[@BestCommentEver]

I’ve had gas struts on my car where that groove on the side gets narrower as the strut opens allowing fast movement at the start and a slow down as it reaches the end of travel. A useful effect with practically no additional engineering or manufacturing cost.

[@mikew1547]

There was a LOT of engineering and manufacturing effort (i.e. many years of R&D) that went into figuring out how to get that groove just right. But yeah, once we had it figured out and the necessary equipment added to the manufacturing lines, no additional cost other than 1 extra component in the piston.

[@MultiMikim]

13:12 Oh. Happy birthday, Tony!

[@firstmkb]

That made a whoosh as it went over my head, thanks!

[@jaketaraj763]

Fantastic explanation. Your humor gained a new follower.

[@KevinGre]

Bonus was required for me to finally get it. Another way to think about it is to consider a just a rod that is sticking out into a really big vacuum, or just a space with much lower pressure (say atmospheric pressure). Pressing that rod into the compressed area takes force and does not change the pressure difference between the two areas very much. The piston is just there to keep the rod from coming out all the way and centered in the piston, but that can be added after. In your example it's 90psi on 2 square inches even with no piston there. The piston does not even have to be a piston. Any shape that keeps it from popping out the glass container and aligned will work.

[@peckhamian]

@KevinGre I was looking for this comment and it is the one that makes the whole thing easy to understand. The connecting rod is the piston, it has very smooth surface so it seals better. And the whole barrel is a cylinder. And that round part that is inside that was reffered to as a "piston" has the same pressure on both its surfaces and can be any shape, it only prevents the real piston (the rod) from kinking or bending when moving in and out of the barrel. TOT made it here unnecessary complicated. He should show another example where inside that glass jar is a simple wooden cross that helps the wooden dowel/piston move in desired way. For me the greatest wonder in those gas pistons are the seals that keep the gas inside pressurised for many hundreds/thousands of hours of use. I wish TOT elaborated more about these seals. And I was scrolling for more than 15 minutes to find your comment.

[@MrSKRZYNIU]

I’ve almost forgot I subscribed one day. You can imagine how happy I was you reminded me that I did. Nice to see your hands in perfekt, speakable condition.

[@certuv]

Thank's for posting, you have sorted a query I have on a difficult roof hatch design I am about to install.

[@KingJojoB]

Tony back at it again with a banger upload

[@justinpedersen9174]

tony dont miss

[@Bob_Adkins]

Tony's is the only channel I give a thumbs up to before watching the video.

[@opendstudio7141]

Engels Coach Shop. Amazing craftsmanship and projects.

[@mewintle]

The effortless humor of this is amazing. I’m now a subscriber

[@hedning003]

last time i checked my tirepreasure was 2 days ago,when i filled up the tank - someting my grandfather taught me, he was born in in 1894,so everything he said was more or less law, he passed away in 2002,at the respectable age of 106,so everything he said , i obey!...coolest guy i've ever met

[@jonathanrichards593]

Curious coincidence - the time between pressurizing my tyres and watching this video was about 7.5 hours. I hadn't checked the pressures for months before that though, sorry, Grandfather. PS They're tyres here, but I still put 34 psi into them, not 234 kiloPascals.

[@Bbeaucha88]

Skip part of a ToT video? Not on your life!

[@chriscarlcm]

First time viewer here; I subscribed after watching just a few minutes of this video. I can't wait to binge the rest!

[@karl-artureiskop4942]

2:22 it is designed that way probobly because a tension spring could over extend and become stretched, that mecanism can bottom out and avoid damage.

[@dyhidrogenmonoxide]

Mr. Tony, I don't know if this is the third method you were forgetting, but one other way to generate constant* force is with a vacuum cylinder instead of pressurised gas - imagine placing your finger over the end of a syringe and pulling. Apparently they use this method on an exercise machine on the space station, since weights are not really an option. *subject to barometric pressure & the volume of atmosphere you operate in

[@nickknowles6229]

Bigman.. I'm dumb as dirt but after watching this I can safely say that you learn me real good! Very good !

[@Carlobergh]

The gas spring in your previous video spurred my interest… wait no. I’m interested in all your videos!

[@tstthomason]

“It’s arts and crafts time” F*ck yeah!!!!! Arts and crafts are what we’re here for.

[@raddtadd22]

I need to change some of these for a vehicle because they are worn out. I was wondering how the gas springs work. Now I know. Thank you.

[@leybraith3561]

....The sliding gas tight seal that allows shaft to extend must be something rather special....Stunning that many gas springs operate in harsh environments with little in the way of dust exclusion from the shaft....Extraordinary!

[@dermarv7569]

Well, an extention spring will be damaged, when you pull it to much. But you can pull on your converted compression spring, pushing it all the way together, and it will just 'unfold' again, when you let it go.

[@lupuszzz]

The effort to change the screwdriver in the background is incredible - how I like this kind of oddity.

[@prjndigo]

Yup, its about 14 times easier to divide 500 by 25 and most people don't even consider their car is already deforming the tires.

[@catguy2043]

19:32 "thats right!" [It goes in the square hole]

[@Visigoth_]

1:53 I think It's designed that way so that you can disassemble it... I have one of those on the Utility room door in my old house, and when I need the door to fully open I always squeeze one of the (what's it called? The two parts "inside the spring" 🤔😅)... well, w/e... it's so you can disassemble it. 😉👌

[@mauriciomarianocarneiro]

We were waiting for you!!!

[@grizewald]

"When you're trying to be the fun uncle..." You sir, owe me one new keyboard! 🤣

[@jum5238]

Is this the pull my finger part where gas comes out?

[@jeetsheta]

The spring no longer acts as a spring because once you drilled the hole, the overall pressure in the system restored to atmospheric pressure i.e. 14.7 PSI and doing some math tells me that the piston side of the spring (assuming 0.8 sq.in.) experiences about 11.8 pounds of force while the other side (assuming 1 sq. in.) experiences about 14.7 pounds of force. Comparing them, the difference of about 3 pounds is not enough to overcome the friction between the walls of the cylinder and hence the piston stays wherever it is. This is not the case once the cylinder is pressurised where non-piston side will always exert greater force.

[@roman.4110]

While working on air springs for a living I have 100 percent enjoyed this video. Just like every other video that came before it. Keep up the good work!

[@Gergus]

Honestly you do the wildest things that make no sense - like the Subscribe on the silver air piston after 11:00 and the change in screwdriver colours at the start for no reason at all. It's hilarious and I have no idea why...

[@ChillGuy511]

Wow! That's so cool! I've recently started working on hydraulic cylinders and never thought of such an idea! One would think the piston wouldn't move with a hole in it!

[@Adamsadventures83]

The screen door spring is designed to be "captured" making it relatively safe from injury should it break. If it was a stretch spring that was not captured in any way then upon breakage or being dislodged from its mounting point it might fly at mach 7 right towards your eyeball

[@boots7859]

No, because you'd see the same nanny-state requirements on every door in existence. They are made that way for the often common case wherein a wind gust will catch a door and attempt to slam it at mach speed past its safe/desired stopping point. Man, where do some of these comments come from? Seriously, do people just sit around all day on the throne thinking of stupid answers to questions?