The interesting engineering behind the SHAPE of Train wheels!
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- Опубликовано: 27 дек 2021
- Have you ever wondered why the train wheel shape is conical, not straight. Let's explore this simple, but genius invention in detail.
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At 80 years of age I now realise that "YOU ARE NEVER OLD ENOUGH TO LEARN" !!. hehehe
Good old man ☺
Very true, it’ a gift
👍🌹
No shit !
Exactly right.
"The designer knows he has achieved perfection, not when there is nothing left to add, but when there is nothing left to take away."
In the open world
There is not such think as perfection, but rather compatibleness of result and expectetions (depends on system.)
@@theoryianabsolute8777 ok
@@theoryianabsolute8777 ok
@@theoryianabsolute8777 ok
I knew the shape was to keep the train centered on the track, but I never even thought about the differential action when going around curves to be honest, pretty interesting how simple it is!
i don't understand first reason
Same 🤷🏻♂️🤦🏻♂️😂
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@@info1841 first reason was difference in radius b/w two wheels
When rolling left wheel has greater radius than right one. Becoz of that left wheel have to cover larger radian angle which is directly proportional to distance covered.
Meaning
Larger the angle larger wheel have to cover distance.
So when turning left wheel right wheel covers lesser distance then left one.
Second one:
When rolling right wheel tries to move towards left wheel but end up balancing each other at the end because of shift of centripetal force towards their Centre.
@@info1841 It's just the weight finding balance. The slight weight difference forces it to want to stay center even when turning as long as speed is reasonable for the curve.
After working in our subway system, the rails are also pointed slightly inward. It's very slight and looks pretty straight until you take measurement. The plates holding the rails to the ties will show a difference in height from the gauge side to the outside. Turns are also slightly shifted higher towards the outside of the turn which is why when track inspections are done, we have to take cross level readings as well as the gauge.
Exactly. Glad you noticed that they missed the inwards tilted rail head, in the video graphics. The higher outside rail on a curve is called Super elevation.
@@railtrolley
'Superelevation' is an American term.
The British is 'cant'.
And the Russian is 'elevation of the outer rail in a curve' ("возвышение наружного рельса в кривой"). 😄
Driver (engineer in N America) of 40 years here. I've had to explain this to several trainees over the years and none of them had any clue of this phenomenon before it was explained to them. It's just not something the average person wonders about. I also explained (not to criticise as your video is excellent but you probably should've too) that the further apart the wheels are (the wider the track gauge is) the more differential action is needed because the outside wheel has to travel a LONG way more than the inside wheel but train wheels and the rails they run on are only around 80mm (3") wide so the wider the gauge, the less tight of a curve the train can negotiate. That's why mountain railways are often narrow gauge. Narrow gauge is cheaper to build than standard or broad gauge and when people are told that, they always say "because the sleepers (ties) are shorter?". Well, short sleepers probably are cheaper than longer ones especially when you need thousands of them but narrow gauge is cheaper because you can go around mountains rather than having to tunnel through them because you can't negotiate tight curves.
Knowledge speaks
Is that why Brunell's wide gauge never caught on?
@@therealrobertbirchall given Japan's high speed network is narrow gauge , I don't think it was down to the physics of cornering, Some African and Australian railways are narrow guage for freight too so that also wasn't a consideration , Brunel was simply a victim of the politics of his time, also the added cost of wider guage , wider track beds tunnels and other assorted infrastructure. I personally think wider guage would have been better if adopted as the main standard .
im just the average joe 39 years retired owner operator of two macks but i have just learned somethings i always wondered about. (with the wheels ) also i happened to have an inspector explain the laying of ribbon rails while watching for two hours how they install new rails ( i always wondered how they prevent the rails from bowing out ) well what they do is nail down the rail about every fourth tie then they heat up the rail and nail down the rest of them this helps to prevent expansion when the temperature get real hot also the machines were owners of the company that layed the rails . this was done on the wisconsin southern line from waukesha to milton two trains per day the guy said that these rails could last up to a hundred years
Thanks, now I know more about trains.
I had never considered the necessity of differential action when a train turns a corner, this explained it very neatly and the animation was excellent nice and clear. Thank you very much.
Neither had I Thomas. I have wasted my life.
I always just assummed they sucked it up and let one wheel or the other slide a bit over the tracks.
I said out loud "THAT'S what a differential is?" (I am not a mechanic, but I know a car has a differential.)
@@joemorris143 You did.
RUclips is changing the world.
This is simply incredible. They say simplicity is the cornerstone of brilliance. This invention is extremely simple and even more so brilliant.
It is incredibly simple( just for understanding not invent !!)
And simply incredible😀
@@Abhinav-gu2ui i don't understand first reason
Automatic Transmission says hold my beer.....
Speaking of incredible, my sister can pull a train.
I also learned recently that the conical wheels produce much less drag on the rails than flat wheels would, and that is also why the rails are slightly convex: less contact = less friction = less drag.
This was one of my first thoughts, and surprised they didn't cover that
importantly this has to be balanced with the strength of the materials used such that the increased pressure force from reducing the surface area isnt enough to buckle or crack the wheels or the tracks
@@callanc3925 or wear them down to quickly
The wheels are rolling, not sliding (unless something is actively going very wrong I guess), so the friction between the rail and wheels shouldn't really matter. Additionally, friction is independent of the size of contact surface. However, I think your point on the small contact area being useful still stands, as it minimizes the amount of perfectly circular material that needs to be fabricated.
@@samkerski it does matter, because trains don't use tires purposefully, the less drag/friction a train has makes so it moves freely over the tracks, i'm not a engineer or train specialist so i can be wrong but i think that makes trains need less power to keep up at the same speed or to accelerate, since a train is very heavy and when it is accelerating it IS basically sliding the wheels on the track, same for braking, i presume trains basically just move the wheel as they want and let the friction catch up to it.
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1) next level animations
2) next level teaching
3) next level examples
I love this channel
4) next level train
I watched many magyar vasút video no one example similar.
The main reason for success is the animations and American narrator. There are channels with only one of those but didn't succeed
And the absolutely crappy music stopped after the intro.
nExT LeVeL
I like the colors. Can someone get me a juicebox please
I have seen lots of train wheels, but never looked close enough to see the taper. Makes perfect sense! I always assumed that it was just the flange that kept the train on the tracks.
Pretty sure the angle is exagerated in the video to clarify the concept. You'll notice the animated wheels are very wide, another exaggeration for clarity.
Can anyone explain if the differential effect limits how the sharp a turn can be? I feel like that also coincides with the fact that inertia of the train would also limit the turn radius to prevent it from tipping over and derailing. Thanks!
The flanges are required because in turns or on irregular tracks, the wheels could still push themselves off the tracks without them.
@@edwinerickson6035 i tinn dares ahh, king pin two elp, negotiate tunzez
@@enzoorciuoli328 what?
Having had toy trains for years, I had no idea that the actual wheels were as cleverly engineered as that. They appear to be far more tolerant of rail gauges than one would suppose.
eh that not impressive, god designed my shaft, much better shape
check your toys, are their wheels also engineered like this? :) too sad I did not have such toys :( maybe I should buy them now as an adult :D I have bought rc car but just played few days and now it collects dust
A worthy note on the conical shape of the wheel is that it prevents achieving higher speeds . as the constant oscillation automatically damps the train speed
Can you elaborate please
@@JessifurC wheels are going left and right and train cant go brrrr
@@ALEX-db6rr lol ah gotcha, I thought Maher was making a statement on the limitations even while traveling entirely straight.
@@JessifurC its also true for travelling straight since wheels going left and right as well, just no as much as on turns
@@JessifurC The more tapered the wheels, the more the train will sway back and forth. This can create a positive feedback loop in which little sways lead to bigger and bigger sways. At low speeds this isn't a big deal because the horizontal momentum will be offset by the weight of the train. But at high speeds big oscillation will cause the train to derail.
0:58 This guy is using the silver play button as train rails Lmao 😂
I remember Feynman explaining this years back. Was so fascinating to learn how something so simple could have such a profound application and effect.
send me the link
@@anujtuladhar8318 ruclips.net/video/P1ww1IXRfTA/видео.html
@Lee Ovenden BLESS YOU for not only giving the correct link relevant to the thread, you also gave the relevant time stamp in a 10+ min video. Thanks Lee Ovenden!
@@Derpkips31415 Seinfeld : 'The question is, why do we so dearly need another explanation of such a simple thing already well explained by Mr Lesics? George : 'Mr Feynman is the boss! George only trust Mr Feynman! George is out of here!'
The design of a soda can in also ingenious as well you should watch it
Makes you wonder when the designed the wheels if they actually understood what forces were actually keeping it on the track, or was it just trial and error and this was the result because it worked the best
Interesting question
Id say given that newton predated the creation of trains by a good 150 years or so it was the former, but as with any designing a bit of trial and error played a part too
@ Lazy Leftist This isnt so much an invention as it is a practical application though. They knew what the wheels needed to do they just had to figure out a way to make them do that
trial and error, and the science was just an after thought. cause honestly who would call it science if it failed?
The idea has been known for centuries. Incline a ladder at a shallow angle & you can roll wooden barrels down it without them falling off.
I used to work in a machine shop that used a very large lathe to re- turn the taper on box car wheels. The taper would start to wear flat, causing the wheels to wander on the tracks. The machinist would use a template to check for the proper taper. It was a slow process, because the wheel surface becomes surface hardened as it rolls along the tracks. You would have to machine the wheels at a slow speed because of the diameter of the wheels as well. (Surface Feet per Minute). Great video!
I never thought of how conical wheels could compensate for different lengths of travel when rolling around a corner. I just assumed each wheel rolled independently and wasn't firmly attached to an axle. But now that I think about it more, having the wheels firmly attached to axles means the same differential action caused by the conical shape would also cause the wheels to _actively steer_ back to the center of the track if the wheels were shifted off-center. That's brilliant.
ruclips.net/video/3l9Hm_fMI2g/видео.html
Qqqlaq@pq1qqq
💯same thoughts ✌️✌️👍
the conical shape is not going to make a huge difference in travel. The wheel on the inside of the turn still drags along. One other thing not mentioned is that the conical shape allows for a ticker stronger wheel with a small contact patch thus reducing friction as well.
That's why city trains squeek on turns.
I am an Engineer in Indian Railways and I was asked about this question in my interview...I know the answer but the way you explain about the acting force is very good. Thanks 🙏 🇮🇳
Thanks for your service 👍🏻
@@ChintanPandya01 it is my duty brother....Hope Indian Railways make your journey beautiful 🙏
@@sheku1803we brother that you become successful in life by being successful in your duty.
God bless🌷🙏
Most of the wheels I see on trains are already flattened.
Question?? So how often are the wheels replaced?? Or maintained?? The process can be costly.
Is this the reason trains derail mysteriously??? Because the wheels are worn past service limits???
Even our trains are having the same shape? I thought ours are like locked with wedges on either side of the track line.
Physics play such a huge part in our daily lives. I could have never imagined just how much so in the rolling of a train wheel. And just think this knowledge was known back when the train first rolled down the track!
Physics EXPLAINS how and why things are as they are - and, thereby, why they can't be any other way.
Physics doesn't cause things to be as they are.
(BTW - 'physics' is an 'uncountable' noun and, therefore, treated as 'singular', ergo "physics playS...". Unlike the laws of physics, the accepted rules of English grammar define how things must be.)
Know what I love most about this? No annoying background music. Thank you. Wish more channels were like this.
yeah. only annoying background misalignment of RUclips plaques.
0:30 Its funny how he is just casually making rails out of silver play buttons
Only now did I know that the 2 tram wheels are fixed on the same axle but operate as an independent differential. All these simple principles are very well applied by scientists. Thank you for sharing this great video.
They're applied by engineers, not by scientists. ;)
@@SimpleAmadeus: Nobody in the real world is a pure scientist. Even lab scientists have to apply principles to build equipment for experiments.
Engineers, not sc..... Already said, have a good one 🖐️
@@deusexaethera Most of what people call "science" is actually engineering. Relatively little science occured in the past half-century.
@@SimpleAmadeus Actually, there have been more scientific papers published in the past 10 years than in the entire 20th century, but 99% of those papers are worthless and some are downright moronic. I cannot fathom how, for example, medical researchers have been going on about moderate correlations between BMI, fat and health, but there are almost no studies on the underlying mechanic that's the root of it all and explains why some obese people can remain healthy throughout the life - that is, the number of cells in the body doesn't increase after the age of 20. When they're full, they can no longer function and fat&sugar become systemic.
Thanks, never really thought about differential,but the changing diameter of the wheel as it rides up or down the cone was not something I had considered.
Very elegant design
I didn’t think about that either. Always learning something!
I am 89 years and I too learnt something new. Thank you for sharing your video
The use of cup was really intuitive to explain this. We can do this experiment at home as well.
Thanks 🙏
Only if you have a few RUclips awards at hand to make a track :-)
@@Nerd3927 that was a good one LoL
A further parallel would be a flat roller (toiler paper tube?!) - there would be no self-centring force helping it to stay on the track, though it would be better than the opposite placement of cones.
ruclips.net/video/kZEpJFjxYek/видео.html
ruclips.net/video/1y-8AOmdFyo/видео.html qrf
How elegant, as good engineering should be! Solving huge engineering problems using just simple geometry. No gears, extra shafts, or separate machines or control electronics.
The engineers were like, “Just add a taper and we’re good.” 😂
"Simplicity is the ultimate form of sophistication"
@@emponator хйфйшаж
@@emponator ඞඣඛගකඣඞපඪ
"The engineers were like ..." ....what are you ....a four-year-old? Learn how to communicate intelligently ....not like, ya know, I mean, kinda, ..... If you want people to listen to you and take you seriously, then communicate intelligently .....no gutter talk like in a bar.
@@taxicamel You say that, but you're the only one here who seemingly invented their own grammar. I can understand Matthew's comment perfectly, but I would have an easier time understanding the russian comment in this thread than trying to decode whatever you wrote... Your capitalization is inconsistent, you have double spaces between sentences on multiple occasions, and your weird use of ellipses leaves your total sentence count up to interpretation (my guess is somewhere between 3-7, no wrong answers though!). You also told him to "communicate intelligently" twice which is very ironic. Also what is this: "....not like, ya know, I mean, kinda, ....."? Did you have a stroke? That comma followed by an illegal 5x ellipsis genuinely gave me an aneurysm.
I'd always wondered how trains handled the differential rotation of going around curves given that they have a fixed axle with no differential gearing. This answers a question that has bugged me for years.
Seeing this has also allowed me to figure out another thing you didn't mention: the reason why there is a definite limit to how sharp a corner a train can turn. If the turn is too sharp (which is certainly the case in your video, although I realise the turn was exaggerated for illustrative purposes), the differential rotation required to negotiate the turn becomes greater than the differential rotation that the conical form of the wheels can supply.
The ratio between the inner and outer radii of the wheels thus represents a hard limit on the tightness of any turn the train can make. This is why you can't have right-angle corners on railway tracks, and why they can only curve gently.
If the cones were steeper, thus giving a higher inner:outer radius ratio, the train would be able to take sharper turns. However, the steeper slope of the wheels would also increase the lateral forces between wheels and rails, putting increased compression and flexion stress on the axle as well as expansion stress on the rails.
It would be interesting to work out the optimal inner:outer radius ratio to maximise the possible turning angle while keeping the stress on the wheels, axle and rails within structural limits.
Sure but.....a train doesn't only have wheels....so you can't really make a sharp turn
@@Sweet-bx2ec Of course. Without actually doing the maths, but considering the trigonometry involved, I would imagine the relationship between the steepness of the cone and the sharpness of the turn that would enable is related to the angle tangents, meaning that the stressors would increase asymptotically with cone steepness, reaching infinity at 90 degrees which of course would mean the cone has no depth.
I'd imagine that stress curve would rapidly become untenable, in fact, if you took the cone angle much past 30 degrees.
@@Sweet-bx2ec Also, the length of the bogie would also be a factor in that limit as per your comment "doesn't only have wheels".
High elevation curves also utilize rail lubrication devices to help prevent premature rail and wheel wear.
Calculus
I've always wondered how the differential action was achieved. Now I understand. Those early train engineers were brilliant! And the solution seems so simple.
I never knew that something as simple looking as train wheels were actually this ingenious!
Yeah, train wheels are the perfect example of keeping things simple, no need for expensive over-engineering and complex mechanical parts. Very simple but very clever.
To be fair trains are on tracks so it doesn't need complex mechanical parts, vehicles need to manually turn on the roads while trains just needs to speed up or slow down.
@@slowville6637 I bet if the train was invented today it would have involved something more complex.
@@laernulienlaernulienlaernu8953 Well you can say that about anything if it was invented today because our technology is far from simple design.
The highspeed bullet train being built today is way more complex than regular noisy & ruff trains but it is also way more superior in almost every way.
@@slowville6637 that's what makes things like train wheels so impressive, because they had to find solutions without all the tech we have today. They might seem primitive now but to this day train wheels haven't changed despite all the advances in technology.
@@laernulienlaernulienlaernu8953 Look what I'm saying is they are simple because they are on rails, there is something guiding the wheels so you only need wheels that will ride along the rails without flying off, just look at roller-coaster.
They are genius but not complex for that reason, cars are complex but they can do so much like racing/drifting/donuts & ramp jumping, they can even go off road which a train can never do due to simple wheels.
I enjoyed this lesson about the movements of the flange wheels, even rolling through the curves of the railroad track.
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Train wheels have flanges on the inside of each wheel to prevent the train from derailing, very good video you have here, Also the railroads have huge grinding machines that grind the rails smooth several times a year. This makes the wheels and rail last much longer. I have videos of these machines in action.
Wide world of Trains, Intersting name
He mentions the flanges and their function at 2:20 in the video…
@@JaguarXJ 😘
Indeed, they also have a slight concave more better contact
pg rating?
When brilliant engineering meets brilliant simple explanations, this is one of the highest quality videos I've ever seen in a while.
@@diegofondoo1780 Thanks for pointing that out, I didn't mean it that way lol
ruclips.net/video/3l9Hm_fMI2g/видео.html
I was 10yr when I looked at the wheel shape and figured it out, but an explanation of this depth is really amazing to listen to.
Two things. First The ancient chariot wheels are the same distance apart as the modern day train wheels
Second. Barrels have the same conical shape on each end. This allows them to be rolled on rails up and down ramps.
Okay
How do chariot wheels have anything to do with this?
@@troyt6532 Wooden wheels like those on chariots form 'ruts' in dirt roads over time. The romans had a standardized axel length of their chariots, so their wheels all fit in the same pair of ruts on every road. After Rome fell, the roads remained, so later Europeans built their carts, wagons and buggies with the same width axel to use those same ruts. When the train was invented, the designers had to choose an axel width for the cars, and they went with what they were already familiar with.
@@caseyb1346 Do you know why Spain has wider railroad tracks than the rest of Europe?
@@caseyb1346 see, now this is actually some interesting stuff. More people need to be like Casey.
As a dispatcher in a Train Control center in Germany , i can add that they also have this shape that we wheels get worn off evenly. Because they move from left to right all the time they don’t get stains in the wheels.
This is wonderful! Your simple experiment makes students think, and then the detailed animation explains it well. I learned this from Prof. Feynman's video.
I learned more from this video than from my entire 4 years of college. Good work🔥
I learned so much about trains without expecting to.
It also has a 3rd passive action. It continuously generates the smallest available contact patch. Less contact less rolling friction more efficiency.
Less contact area results higher bearing stresses. Thus in order to maintain that small contact area, the two materials to have high hardness and stiffness.
I think that's negligible here,that is true for pneumatic wheels like car and truck tires.On the other hand less contact also means more wear since load is concentrated over a smaller area but in this application there isn't much choice.
@@_Wai_Wai_ No it doesn't, the bearing is at the hub and has the same contact area and pressure regardless of the area of contact of the outer rim to track.
@@mehmettemel8725 steel on steel is going to wear no getting around it. Rolling friction is definitley a factor though. A train with hundreds of tons on a hundred of these axles is going to generate some resistance pretty quick.
@@noname-nd8ec He wasn't referring to that kind of bearings. The track bearing the weight of the train.
Another elegance I see is that the conical shape would not be affected when the wheels and the rails expand/contract by heat. It just works!
Short of taking a blow torch to tracks or pouring liquid nitrogen over them any shift in temperature in the environment would have a negligible effect. Whether it's 10°F or 100°F the tracks are effectively the same. The difference in expansion or contraction between 10°F and 100°F is 0.00058", which is smaller than any tolerance a train or the tracks are built to.
@@TheBoatDude True. I didn’t realize how small the effect was.
A quick math reveals that a 30m iron rail would stretch/contract about 1cm with temperature difference of 30K. It is completely negligible when it comes to the width of the rail like you said.
0:34 Pretty sure the "tracks" are the RUclips play button. Subtle flex 💪
0:34
RUclips silver play button as track.
Bro is flexing.
I’m amazed at the ingenuity of the rails: how they can remain upright under such tremendous loads, including the sideways force exerted from the conical shaped wheels, with only spikes driven into wooden ties to hold them in place. Those designer/engineers so long ago were pretty bright: simplicity is genius!
Physics 🤩
@@Amin10XD .. 'evolution' explained in one word > biology - class dismissed.
'physics' - now you understand everything from a teacher who can pronounce the word.
Actually most of the time the rails are not upright. :)
ruclips.net/video/1y-8AOmdFyo/видео.html ryg
Yeah, it's a shame we don't have too many bright people left around anymore. We rely on simulations and modeling on computers to design our parts, rather than critical thinking.
I worked at a place that designed aircraft engines a long time ago as a machinist, and one day I asked one of the engineers how she calculated dimensions for designs in her work. She showed me a program the engineering team used, which was basically a beefy version of CAD, and it did all the number crunching for you. You told the program how big or small you wanted certain angles and it would automatically shape the part for you and then you could perform fluid/airflow tests within the program to test your design. You could manipulate the part with a selection tool where you could click and hold to make certain angles smaller or larger and everything if you wanted to refine the design further.
Once they were happy with the program, they would copy the file for the part from the CAD program and run it through a 3D printer and use the plastic as a prototype demo to display to management. Upon prototype approval, they would export the dimension mapping to the mills and wire EDMs to make the final metal-formed parts for QA and final production approval. The process is amazing, but also pretty sad. If you took that program away, I guarantee you almost all of those engineers would've struggled to finish their projects.
I thought my car was amazing when I found out in highschool how this was achieved. Now I'm blown away from this. I realized what it did immediately as soon as I saw the (larger/smaller) contact surface area on the track.
Totally don't understand why my shop teacher didn't use this as another example of how it works.
Nice video, appreciate the learning and lesson in less than 5 minutes.
I don't understand its concept, yep, I am talentless.
"Totally don't understand ...." Yup ..."totally". Spoken like a child .....today's generation.
@@taxicamel You tell 'em sir, them pesky kids these days can't even speak or write proper english and we should not stand idly by it.
The wheel flange is also very important to keeping them on the rails . Once the flange gets too thin or wears into a double flange its time to replace the wheel .
The first two points of logic are revelatory--the conical angle corrects the tendency inward, and compensated for angle differential. Wonderful.
I worked in the Railway for 38 years as a Guard in charge. About 37 years ago I heard about this wheel technique. But the normal people do not know about this. Some are not never thinking about this technology. Thank you.
I worked for a small RR in Arkansas and I was taught a very rudimentary way to lathe the wheels on our locomotives out in the field, not in a shop. It was labor intensive, filthy,hot and sweaty work but very satisfying.I had to jack up the locomotive, unhook the cables from the electric drive motors and hook them up to the welder on my service truck to make the wheels spin. Then I attached a lathe to the track under the wheel and manual cut and measured until the wheel was back in compliance.
Everyone is a gangsta unless that boy comes and pushes the train wheels with his bare hands ...🙌🏻
That shape of the wheel which appears when a cone is cut parallel to it's base, is called Frustum, the upper cut part becomes another cone, but the lower cut part is called Frustum
Wtf is that u r trying to say
@@chandanprasanna9755 just some extra info from 10th grade geometry.
Frustum could be of a base of any shape with an apex, meaning pyramids, and cut at any angle (isn't a right frustum). For a video about trains for laymen, I think truncated cone is adecuate.
Black+Purple -~- I think you mean truncated cone!
Thank you. I shall need that some day! Maybe in a quiz, maybe to shut up my smart ass mate!
You forgot #3!
In a turn, the conical wheels tilt the side of the train downwards toward the inside of the curve, making the load more stable, and comfortable for passengers.
But at last he has mentioned the centrifugal force. I Hope that is enough
In a turns tracks themselfs are much more canted towards inside than is provided by conical shape of wheels. Also in some high speed trains cabins are also tilted from chassis to the inside in a corners for comfort that technology is called pendolino.
@@derimmor It's called a tilting train. "Pendolino" is a specific family of those trains made by Alstom SA.
Superb explanation!
It has been said that we don't invent principles, principles already exist in nature. We only discover them.
The factor about the differential action it the new thing i learned, simply brilliant!
In addition to this, sleepers are not flat rather they are canted at same slope as wheels cone (usually 1:20) to assure that flanges are not rubbing against the rail in straight track. This also assures a good contact between rails and wheels and less wear and tear; increasing the life of rails as well as wheels.
What are "sleepers" in this context? Is that the top of the rail?
@@pstrap1311 If I'm not wrong in US they call them "Tie'" . The concrete slabs under the tracks.
@@rbflowin_TV oh, I see, thank you. Yes, we call them "ties", because they "tie" the rails together, I think. They used to be made of wood.
In wooden tie/sleepers and on some concrete ties, the tie plates using the spike system or a screw system is thicker on the part toward the outside of the gauge than the inside of the gauge so that the rails are tilted toward the inside. So on those, the tilting is accomplished not on the sleepers/tie, but on the tie plate situation on them.
@Master the Blaster not everyone is american
Now I understand what the instructor was trying to ask in my college lab exam viva questionnaire session. He just asked "How does a train turn? I answered "tracks turn so does the train".
You should have told him you steer the train with the hand brake wheel. L.O.L.
Your answer was right too
And all these years I thought it was the flange on the wheels that keeeps trains on track. And now I know what really keeps them on the rails. Thanks👍
FABULOUS!! Loved it! Explained so very lucidly!
This is 3:05 am, tomorrow ill be on early shift, and i just found out how a conical shape is very important to train wheel.
That "differential" phenomenon is actually the reason why the wheels are corrected on the straightaway as well
Good observation.
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Every time he says, "Interesting right?" I feel like he's gonna follow it up with "Wrong."
Very badass...
Thanks for explaining this so I could easily understand.
A similar concept though not exactly the same is the use of “dihedral angle” in airplane wings. The wings of an airplane are not parallel to the ground but tilt slight upwards. This provides automatic roll stability in flight. If the airplane were to roll slightly in flight, say because of turbulence, the horizontal component of the forces always cancel out but there would be a force differential in the vertical components which would act in the opposite direction to center the plane.
Incidentally, with the advent of microprocessors, some fighter jets were designed with inherently unstable geometry, so as to improve manuverability, which had to be constantly counteracted by computers.
@@deus_ex_machina_ Why are you using past tense? That's still the case, physics haven't changed.
@@Derzull2468 because the jets that exist now were designed in the past. The past is for designing the jets not them existing.
FERNGULLY :BATTY:
"LIFT, I NEED LIFT!"
@@charbelalam2648 But it's still how we design them right now, it's not a bygone design method that no longer exists.
This is exactly the same mechanism of crowned pulleys, wonderfully explained
I remembered when we used to run rolls of film through film processors in the 60s, the rollers were high in the center. I remember an engineer explaining why the film didn't run off to the side, but couldn't remember today! I couldn't find the answer Googling, till I read your comment and searched RUclips for "how crown pulleys work." Thanks! ruclips.net/video/TNuzi-jMXoY/видео.html
This is something I would watch at 3am, ironic, because that's what I'm doing right now
It's 5:00 in the morning and I'm watching a video about train wheels... and enjoying it. I'm very sleep deprived.
A similar process occurs in the knee joint , wherein the lateral condyle of the distal femur is less curved than medial condyle making its radius of curvature more than the medial condyle so that some amount of rotational motion occurs during terminal extension of the knee and the femur rotates internally.
Fascinating.
Sheesh
In all the years I taught Technical Traffic Accident Investigation and Traffic Accident Reconstruction, one of my first questions to the students on day one... "How can a train turn a corner with solid axles?" This video does a good job of explaining it, although you left out one factor. What will be the INSIDE TRACK on the approach curve, this track is depressed slightly in tangent before the beginning of the curve. This creates a horizontal lift component in the direction of the curve and breaks Newton's Law of Motion for the object to continue in a straight line. Excellent explanation!! Carl, Washoe County Sheriff's Office, Reno, NV, Patrol Division, Traffic Section, Major Accident Investigation Team (MAIT), retired.
Wished the inside track was explained in the video because I have zero idea what you are talking about
Next time i go to look at the trains, i will have a close look at the wheels. Great posting, thanks.
What a Physics behind the conical shaped train wheels! nice explained, thanks!
It is perhaps worth mentioning that this amazing engineering marvel was created in the middle of the 19th century. As marvelous as these animations are, the depiction of modern high-speed equipment may leave the impression that the shape of the wheel is also modern. It is not. Another aspect of this work of ancient art is the carefully engineered curve that joins the tread to the flange. This greatly exaggerates the forces acting on the wheel as it approaches the extremes of its lateral movement.
There is another aspect of this magic that the video fails to mention. The weight of the car or locomotive pushes the wheelset back towards the center. This is because the conical shape means that as the wider part of the wheel (near the flange) is moved towards the rail, the increased radius means that the equipment above the wheel must be lifted. This is a powerful force keeping the wheels centered between the rails -- the flanges never touch the rail in normal operation.
Finally, it is worth mentioning that rail head is also curved. The tread and rail head interact in a carefully engineered and orchestrated balance that keeps the train on the track, guides it around curves, and reduces friction.
ruclips.net/video/3l9Hm_fMI2g/видео.html
When the train is slightly out of center and the train tilts, it also creates a net gravitational force countering this motion.
Yes, technically true. Sadly not enough to be useful. The French TGV has active elements tilting the train far more than the tiny effect from the profile of the wheels. That is needed to keep passengers comfortable while traversing a bend at speed.
People take trains for granted, including me. But the physics behind this system is just amazing.
Wow, glad the YT algorithms brought me here. I learnt something new today. I've always wondered about this but never questioned why. Brilliant engineering this design, so simple, so effective.
Thanks!
Brilliant video! Something I had never given any thought to before, but this was presented in a simple, yet informative manner. Amazing how something like a shape of a wheel can be so intelligently designed yet taken for granted.
Yes as you said something I learned a while back and yes very clever and simple. And most of us take it for granted. Another thing folks do not maybe know is why is it so very easy to move a train wheel with a heavy load. It is hard and the track is hard no give, not soft as a car/truck wheel and the load needs to be lifted on a soft car wheel. The harder the wheel is the more round and easier to move. I like your video. Thank you. As a kid if something worked. I would take it apart to see why. If it did not work, I would take it apart and try to fix it.
I wonder how long it took for this design to be determined. Remember, the first train was invented in 1804. I suspect a "conical" shape was perhaps quickly determined, but I wonder how long to get to the exact geometry was finalized. Also, realize there is the track geometry to "mate" to the wheel. Wheels wear out and are replaced. Track is "reshaped" by equipment that grinds the profile till it needs replacing. How critical is this "reshaping"? It's been a long time since I heard the term "centripetal" used.
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"It's been a long time since I heard the term "centripetal" used."
In other words, you haven't been involved with physics for a long time. It's the correct term for that type of force.
You can also re-shape the wheels themselves, not only the track. The re shaping of the wheel profile (surface in contact with the track) is critical and must be performed as soon as the wear reshaped the conical surface. How often depends on the kind of track the train runs on: generally, the more turns the train makes, more often it is required. Other factors influence this, for example in the desert where there is sand between the wheel and the track, more impactful wear will occur :)
A wheel found from an 1816 train did not have the conical shape but did have excess grooves on the outer edges from wear. We can only assume led to the change in design.
@@Uomosabbiaa Another fairly common issue is the occurrence of 'wheel flats' on the conical surface, due to brakes locking up temporarily with them skidding along. The other side of the coin then is damage to the track itself, which has it's own problems, leading to more grinding to repair it.
@@johnkeepin7527 this is of course true, but it happen when the braking system acts on the profile of the wheel itself! Most passenger wheel sets today have brake disks either mounted on the axles or inside the wheel body
The cone vs “reverse” cone wheels makes me think about stable and unstable equilibrium in math (and of courses other corners of science, I just know it from dynamical processes), both wheels can stay on the track if perfectly placed, but if the “reverse” cone gets offset just a little, the train goes flying off the rail.
It is about equilibrium. self correcting mechanisms have a stable equilibrium
Another (in my opinion!) interesting example of this is the design of airplane wings.
On passenger jets the wings are slightly higher at the tips than the base, to provide roll stability (also linked to the fact that the wings are below the centre of mass). When the plane begins to roll, the lower wing will generate more lift due to it being more horizontal than the upper wing. As a result the plane will want to stay level.
By contrast, in fighter jets, the wings tend to be level or pointing downwards, this results in less roll stability (and more roll agility) which is desirable for quicker roll movement (and helped by some fancy computers fighting the plane's natural tendency to roll away from level flight!).
Check out dihedral vs anhedral wings for more info!
ruclips.net/video/e-j-Hx7v3oI/видео.html
@@_mickmccarthy very cool! To ask quickly, would another reason for this dihedral wing arrangement be to account for a plane’s wing load, along with lateral stability?
@@garrom5652 Not quite sure I follow, but dihedral wings are more necessary on passenger planes because the wings are relatively low compared to the centre of mass. If they were at the top of the fuselage then the plane would find it easier to stay level due to the centre of mass being below the wings. Almost acting like a keel on a boat.
Not sure if that answers your question though! It's a super interesting topic though (well, for some people, for some I'm sure it's very dull!)
For the same reason airliner wings are also attached in such a conical angle (seen in longitudinal direction), it stabilizes the flight of the aircraft.
Yes, they go slanting down from airplane so that the air pushes down increasing the altitude and producing flight of the airplane. But wobbling is a very common thing in airplane. 😪😪😪
@@OlgaPlaysMatch-3Game is slants upwards and its called a dihedral to help with roll stability
@@OlgaPlaysMatch-3Game you have been obviously smoking the wrong stuff
some airplanes, such as the F16, are electronically stabilized to avoid installing such feature, which reduces its agility. The surfaces apply small and fast correction to account for the unstabilizes flight.
@@yosyp5905 that's right, it's done exclusively with military fighter jets and bombers to make them more agile, the F-16 was the first to use a digital Fbw enabling such a aerodynamical instability. Today all of them are built like this.
Airliners however have to be certified after the FAR25 rules, after this rules aircraft have to be controllable even without fbw systems, so aerodynamical instability is a no go for any FAR25 aircraft
I wish all YT videos were this concise and well made!
Fantastic video, explained and illustrated so well! Thank you!
0:35 Of Course He Has 6 RUclips Play Buttons.. Subtle Flex..
The transition between the cup example and the animation was perfect!
I watched it over a few times, great work!
What a wonderful fact around a very small concept yet so significant. Well done
Hats off to those who found this Perfect solution by discovering conical shape.
Trains have changed so much since their invention but wheel design has never been changed. From 40 kms per hour to 400 kms per hour, wheel design is the same.
2:20 As the wheels move back toward center, their momentum can carry them beyond the center, inducing an oscillation. In railroad terms, that's hunting, as the wheels "hunt" for center. Passengers often call this "wiggling" of the train car. I remember the 1920s-era Broad St Subway cars in Philly that would get into long-duration wiggles so hard that you couldn't lean on the seat back if seated toward the ends of the car, the motion was 1ft / 30 cm or more! Equipment made after 1960 do much better.
Thanks for that. I was wondering if you could get the equivalent of an automotive tank-slapper, and it seems you could until they perfected the engineering.
So, the tail end of the cart is like a pendulum swinging side to side, except it doesn't stop, because the train's forward motion keeps introducing constant energy to oscillating the wheels?
Or was it just after corners that the wheels were oscillating for a while until the momentum died down?
@@evilkittyofdoom195 There's plenty in Philly and NYC, frequent service for less than what many heritage/tourist railroads charge
@@LRM12o8 The rails themselves can introduce wiggles. To give an example: the Market-Frankford line ("the EL") in Philly has this section of new track over Front St. very close to I-95. This was designed for the 1960s-era Budd cars, they wiggled on the rest of the line but ran perfectly on this stretch. Then the replacements (SEPTA calls them M4 cars) came online in 1997, and they wiggle on that stretch worse than the rest of the line in that area.
the movement is always most at the back. This is true for plains and trucks also. Although road trains, 3+ interlinked trailers has been shown to be more stable than 2 interlinked trailer on turns. Train links design allows for less motion transfer than truck links, come to think of it
One suggestion - at 2:57 you state 'the left wheel'. I always use the orientation of the movement for left/right, so I ended up lookin at the wrong wheel.
I think the best way off addressing this would be to say 'the outside wheel'. I think just about everyone will agree that in a turn, the outside wheel is the one opposite the direction of the turn - and thus the one that travels the longer distance.
simple yet accomplishes complex stuff...mind-blowing!!
Interesting. Never thought about and just accepted that it "works". Thank you!
Your simplicity on each topic is awesome
I’m not an engineering buff but this was very concisely explained and something the layman can understand. Great stuff
Based
What a brilliant man , i always thought what the use of analyzing forces , so this video makes me clarified
Thank you for this demonstration
Dude really used his youtube silver plaque as a demonstration of the train rails
That's a heavy flex!
Those who said that the railway is the most advanced transportation mode ever built definitively weren't wrong. 😉
I live in Karachi Pakistan and I like your comment if you don't mind
@@sayyamzahid7312 good to know
I was always so fascinated about the train wheels in childhood, thinking how the really works. Today you taught me about this mystery. Thank you so much for making such wonderful video.
What a great video, thanks!