The interesting engineering behind the SHAPE of Train wheels!

[@SabinCivil]

I hope you can support us today and save our educational service : www.patreon.com/Lesics Regards Sabin Mathew

[@BhaskarRao-k7o]

You Support Us

[@thomashounsome7737]

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.

[@joemorris143]

Neither had I Thomas. I have wasted my life.

[@mbartelsm]

I always just assummed they sucked it up and let one wheel or the other slide a bit over the tracks.

[@kathleenr4047]

I said out loud "THAT'S what a differential is?" (I am not a mechanic, but I know a car has a differential.)

[@Rondo2ooo]

@@joemorris143 You did.

[@GregoryMichaelCarter]

KZbin is changing the world.

[@davidrayner9832]

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.

[@Sudip_Banerjee]

Knowledge speaks

[@therealrobertbirchall]

Is that why Brunell's wide gauge never caught on?

[@Dawgreen]

@@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 .

[@realtruth172]

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

[@ohh9979]

Thanks, now I know more about trains.

[@DrPeppa]

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!

[@info1841]

i don't understand first reason

[@Silverado138]

Same 🤷🏻‍♂️🤦🏻‍♂️😂

[@kingdommusic5456]

No one knows the exact day hour /But we can see the signs events all around us. And by the timeline, Israel is 80 years and 1 generation span according to bible text will be around 2027 , which israel was declared first in 1947 + 80 years = 2027 . so we know we dont have 10 years left as this is 2022 so the rapture, then the tribulation will be before 2030 for sure.The rapture will happen without a doubt and it will happen much sooner than many believe (less than 10 years according to all the environmental, weather,astronomical signs ,israel timelines etc showing ). It will happen without any warning , not one , in an instant , catching masses of people off guard just like God always does, ie the flood ~ a rude awakening . No one knows the exact day or hour the rapture will happen is a certainty . THE RAPTURE CAN HAPPEN NOW at ANY TIME make no mistake !! . Please awake to Christ Jesus which is the ONLY hope NOW and dont let it be found out it IS all true later when its too late & many have been left behind in the most terrible times the earth Has Ever experienced Before and ever will...for anyone who sees this and doesnt know what to do please If anyone hasnt given their life and heart to Christ Jesus will have REAL BIG problems way bigger than any problems Ever had If left here on earth after the Rapture . After the Rapture The USA , Worldwide , will face More evils , Inner city chaos, firearm wars etc etc ,power & water , food shortages , military invasions,mass executions (yes much blood will be required by antichrist ) etctec than it Has EVER been seen Before and you surely dont want to be Here then . We Have Time NOW to change , please seek Christ Jesus while there is still time to save ! no one knows the day or hour of the rapture it will start out just like any other day and it will Take Place In the day In Broad daylight/sunny day , In an Instant FLASH without ANY warning ,& there will be peoples Driver Ids, cell phones ,wallets found in various parking lots,Purses, bill folds Found at work etc etc with NO explanation , and People VANISHING so No One can refute it has taken place. .romans 10:9-10 That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead thou shall be saved! please share with others =IMPORTANT raptureready.com Information for anyone who has come across those that refute the rapture and say that it was supposedly made up and say it was created by darby church in 1700s . This is real good to show it was way before darby , and its documented . also rapture pre trib proofs even in dead sea scrolls .15-1700s/ irenaeus 170ad/ 250 ad / /isidore 4th century sourced by intense search and study by ken johnson kzbin.info/www/bejne/m2Kxp2Cue86abqs

[@prithviraj627]

@@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.

[@rosyc9250]

@@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.

[@fibonacci112358s]

"The designer knows he has achieved perfection, not when there is nothing left to add, but when there is nothing left to take away."

[@jrviade85]

In the open world

[@theoryianabsolute8777]

There is not such think as perfection, but rather compatibleness of result and expectetions (depends on system.)

[@jrod2989]

@@theoryianabsolute8777 ok

[@jpedrosc98]

@@theoryianabsolute8777 ok

[@cryptopoops]

@@theoryianabsolute8777 ok

[@pottabatullamanjula912]

Three things that made this channel so wonderful to me are : 1) next level animations 2) next level teaching 3) next level examples I love this channel

[@cartoonelladefrasz7568]

4) next level train I watched many magyar vasút video no one example similar.

[@SF-li9kh]

The main reason for success is the animations and American narrator. There are channels with only one of those but didn't succeed

[@savage22bolt32]

And the absolutely crappy music stopped after the intro.

[@victorprati7908]

nExT LeVeL

[@yurikawaii7809]

I like the colors. Can someone get me a juicebox please

[@calebdoner]

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.

[@GregMoress]

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.

[@edwinerickson6035]

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!

[@therealtampadude9175]

The flanges are required because in turns or on irregular tracks, the wheels could still push themselves off the tracks without them.

[@enzoorciuoli328]

@@edwinerickson6035 i tinn dares ahh, king pin two elp, negotiate tunzez

[@tfan2222]

@@enzoorciuoli328 what?

[@niekovryburg7901]

At 80 years of age I now realise that "YOU ARE NEVER OLD ENOUGH TO LEARN" !!. hehehe

[@emiliofermi9994]

Good old man ☺

[@ascarez4841]

Very true, it’ a gift

[@ahmedthanoon5419]

👍🌹

[@ShotByGabriel]

No shit !

[@harshsingh-oj2ky]

Exactly right.

[@NightMotorcyclist]

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.

[@railtrolley]

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.

[@u2bear377]

@@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"). 😄

[@Alexg1561-t4m]

I remember Feynman explaining this years back. Was so fascinating to learn how something so simple could have such a profound application and effect.

[@anujtuladhar8318]

send me the link

[@BazGibb45]

@@anujtuladhar8318 kzbin.info/www/bejne/hmLaqGR_jbeZiqM

[@Derpkips31415]

@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!

[@Rimrock300]

@@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!'

[@mrdeafter]

The design of a soda can in also ingenious as well you should watch it

[@deusexaethera]

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.

[@KS7779]

kzbin.info/www/bejne/aZ2ceaCVm7J8aMk

[@txbddipu8656]

Qqqlaq@pq1qqq

[@warriorwithin767]

💯same thoughts ✌️✌️👍

[@Baka_Oppai]

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.

[@fatitankeris6327]

That's why city trains squeek on turns.

[@rungnhietoi3708]

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.

[@SimpleAmadeus]

They're applied by engineers, not by scientists. ;)

[@deusexaethera]

@@SimpleAmadeus: Nobody in the real world is a pure scientist. Even lab scientists have to apply principles to build equipment for experiments.

[@ge-9848]

Engineers, not sc..... Already said, have a good one 🖐️

[@SimpleAmadeus]

@@deusexaethera Most of what people call "science" is actually engineering. Relatively little science occured in the past half-century.

[@JAnx01]

@@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.

[@ObeyCamp]

This is simply incredible. They say simplicity is the cornerstone of brilliance. This invention is extremely simple and even more so brilliant.

[@Abhinav-gu2ui]

It is incredibly simple( just for understanding not invent !!) And simply incredible😀

[@info1841]

@@Abhinav-gu2ui i don't understand first reason

[@ckmoore101]

Automatic Transmission says hold my beer.....

[@tomperry1048]

Speaking of incredible, my sister can pull a train.

[@sheku1803]

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 🙏 🇮🇳

[@ChintanPandya01]

Thanks for your service 👍🏻

[@sheku1803]

@@ChintanPandya01 it is my duty brother....Hope Indian Railways make your journey beautiful 🙏

[@anerkant]

@@sheku1803we brother that you become successful in life by being successful in your duty. God bless🌷🙏

[@Pork-Chopper]

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???

[@saileshram7610]

Even our trains are having the same shape? I thought ours are like locked with wedges on either side of the track line.

[@WideWorldofTrains]

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.

[@currycel470]

Wide world of Trains, Intersting name

[@JaguarXJ]

He mentions the flanges and their function at 2:20 in the video…

[@gudpalebasvant9609]

@@JaguarXJ 😘

[@gordoncracknell7730]

Indeed, they also have a slight concave more better contact

[@talalzahid2241]

pg rating?

[@tomstutz2645]

It also has a 3rd passive action. It continuously generates the smallest available contact patch. Less contact less rolling friction more efficiency.

[@_Wai_Wai_]

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.

[@mehmettemel8725]

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.

[@tomstutz2645]

@@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.

[@fukkitful]

@@noname-nd8ec He wasn't referring to that kind of bearings. The track bearing the weight of the train.

[@mehmettemel8725]

@@SS-du7tr Well here we are talking about rolling resistance and in this case the resistance is not high at all.In fact it is not much different to a ball or roller bearing where it's considered frictionless since the whole axle and wheel assembly is one unit.Maximum friction occurs when the train takes off depending on speed and load and when fast breaking.Rolling resistance and friction are always present but to different degree depending on situation.

[@ajmittendorf]

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.

[@SmokeySauce]

This was one of my first thoughts, and surprised they didn't cover that

[@callanc3925]

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

[@freethenorth7583]

@@callanc3925 or wear them down to quickly

[@samkerski]

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.

[@splintergp]

@@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.

[@francescopetrarca7382]

0:58 This guy is using the silver play button as train rails Lmao 😂

[@ashutoshsuman9473]

The use of cup was really intuitive to explain this. We can do this experiment at home as well. Thanks 🙏

[@Nerd3927]

Only if you have a few KZbin awards at hand to make a track :-)

[@hamzafiroud]

@@Nerd3927 that was a good one LoL

[@iankemp1131]

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.

[@karanmathur5276]

kzbin.info/www/bejne/oYuooX18n92Mm80

[@sanskargupta6493]

kzbin.info/www/bejne/Z6qQaXSFosl5r9E qrf

[@nozyspy4967]

I never knew that something as simple looking as train wheels were actually this ingenious!

[@LukeFaulkner]

0:34 Pretty sure the "tracks" are the KZbin play button. Subtle flex 💪

[@almohhannad]

When brilliant engineering meets brilliant simple explanations, this is one of the highest quality videos I've ever seen in a while.

[@almohhannad]

@@diegofondoo1780 Thanks for pointing that out, I didn't mean it that way lol

[@KS7779]

kzbin.info/www/bejne/aZ2ceaCVm7J8aMk

[@laernulienlaernulienlaernu8953]

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.

[@slowville6637]

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.

[@laernulienlaernulienlaernu8953]

@@slowville6637 I bet if the train was invented today it would have involved something more complex.

[@slowville6637]

@@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.

[@laernulienlaernulienlaernu8953]

@@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.

[@slowville6637]

@@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.

[@matthewgumabon7498]

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.” 😂

[@emponator]

"Simplicity is the ultimate form of sophistication"

[@КлинковДмитрий-ь7я]

@@emponator хйфйшаж

[@mello9586]

@@emponator ඞඣඛගකඣඞපඪ

[@taxicamel]

"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.

[@albingrahn5576]

​@@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.

[@stevefick3919]

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!

[@stevemorgan4702]

That must be one hell of a lathe !

[@davidnovakovich5583]

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!

[@AminFCMobile]

Physics 🤩

[@Chris_Sheridan]

@@AminFCMobile .. 'evolution' explained in one word > biology - class dismissed. 'physics' - now you understand everything from a teacher who can pronounce the word.

[@benlomondbne]

Actually most of the time the rails are not upright. :)

[@sanskargupta6493]

kzbin.info/www/bejne/Z6qQaXSFosl5r9E ryg

[@du4lstrik3]

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.

[@takumimatsuzawa1774]

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!

[@TheBoatDude]

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.

[@takumimatsuzawa1774]

@@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.

[@wolfballzlp8095]

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.

[@stevemorgan4702]

Thanks for that information. Another layer of brilliance!

[@thomasaquinas2600]

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.

[@DJ_POOP_IT_OUT_FEAT_LIL_WiiWii]

eh that not impressive, god designed my shaft, much better shape

[@Name-lt2tz]

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

[@craigmayhan4009]

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.

[@stevemorgan4702]

That's fascinating! Maybe I can add to this. If you take your car in for brake work they will replace the brake pads of course. They will not remove the rotors to true them. Many shops now have a machine that connects to your hub and the lathe portion of the machine cuts the rotor while the hub is being rotated. Maybe trains will do this someday.

[@medicasclepius236]

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.

[@jidangg248]

I don't understand its concept, yep, I am talentless.

[@taxicamel]

"Totally don't understand ...." Yup ..."totally". Spoken like a child .....today's generation.

[@the_headless_horseman9682]

@@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.

[@nirbhaymnnit]

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.

[@pstrap1311]

What are "sleepers" in this context? Is that the top of the rail?

[@rbflowin_TV]

@@pstrap1311 If I'm not wrong in US they call them "Tie'" . The concrete slabs under the tracks.

[@pstrap1311]

@@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.

[@lewisdoherty7621]

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.

[@shayon8012]

@Master the Blaster not everyone is american

[@mahermagdy4604]

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

[@JessifurC]

Can you elaborate please

[@ALEX-db6rr]

@@JessifurC wheels are going left and right and train cant go brrrr

[@JessifurC]

@@ALEX-db6rr lol ah gotcha, I thought Maher was making a statement on the limitations even while traveling entirely straight.

[@ALEX-db6rr]

@@JessifurC its also true for travelling straight since wheels going left and right as well, just no as much as on turns

[@AaronSmith-sx4ez]

@@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.

[@victorthangarajah1622]

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.

[@SALESENGLISH2020]

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.

[@TrollMeister_]

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.

[@deus_ex_machina_]

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.

[@Derzull2468]

@@deus_ex_machina_ Why are you using past tense? That's still the case, physics haven't changed.

[@charbelalam2648]

@@Derzull2468 because the jets that exist now were designed in the past. The past is for designing the jets not them existing.

[@py2724]

FERNGULLY :BATTY: "LIFT, I NEED LIFT!"

[@Derzull2468]

@@charbelalam2648 But it's still how we design them right now, it's not a bygone design method that no longer exists.

[@devo1977s]

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

[@dzenan.m]

Interesting question

[@callanc3925]

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

[@callanc3925]

@ 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

[@MangaGamified]

trial and error, and the science was just an after thought. cause honestly who would call it science if it failed?

[@rowejon]

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.

[@blackpurple9163]

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

[@chandanprasanna9755]

Wtf is that u r trying to say

[@commieTerminator]

@@chandanprasanna9755 just some extra info from 10th grade geometry.

[@rogertycholiz2218]

Black+Purple -~- I think you mean truncated cone!

[@vintagethings9187]

Thank you. I shall need that some day! Maybe in a quiz, maybe to shut up my smart ass mate!

[@stevemorgan4702]

🤣

[@wesleytheamazing]

0:30 Its funny how he is just casually making rails out of silver play buttons

[@carlmclelland7624]

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.

[@johncuervo3019]

Wished the inside track was explained in the video because I have zero idea what you are talking about

[@sweetsingin]

Know what I love most about this? No annoying background music. Thank you. Wish more channels were like this.

[@smartbart80]

yeah. only annoying background misalignment of KZbin plaques.

[@wwfc779]

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.

[@StingofaSingh]

The transition between the cup example and the animation was perfect! I watched it over a few times, great work!

[@tanmaydeo9334]

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.

[@bradleyanderson3996]

Sheesh

[@raymondlucero4999]

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!

[@trueaussie9230]

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.)

[@francescosirotti8178]

This is exactly the same mechanism of crowned pulleys, wonderfully explained

[@peterchristensen9585]

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 KZbin for "how crown pulleys work." Thanks! kzbin.info/www/bejne/in_Yq5xjn7KLpbs

[@dtvjho]

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.

[@vintagethings9187]

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.

[@LRM12o8]

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?

[@dtvjho]

@@evilkittyofdoom195 There's plenty in Philly and NYC, frequent service for less than what many heritage/tourist railroads charge

[@dtvjho]

@@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.

[@adesign5]

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

[@frederikschmeibt7836]

When the train is slightly out of center and the train tilts, it also creates a net gravitational force countering this motion.

[@trueriver1950]

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.

[@chetthejet3896]

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.

[@johndoyle4723]

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

[@SLJ2137694]

I didn’t think about that either. Always learning something!

[@thomasstambaugh5181]

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.

[@KS7779]

kzbin.info/www/bejne/aZ2ceaCVm7J8aMk

[@antagonistickeypress5271]

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.

[@PeterAuto1]

It is about equilibrium. self correcting mechanisms have a stable equilibrium

[@_mickmccarthy]

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!

[@تعلمبنفسك-ر6غ]

kzbin.info/www/bejne/m17NXnuubNtmpas

[@garrom5652]

@@_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?

[@_mickmccarthy]

@@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!)

[@MG-pw7jp]

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.

[@RichardMiller-tq6ut]

That "differential" phenomenon is actually the reason why the wheels are corrected on the straightaway as well

[@w.harrison7277]

Good observation.

[@تعلمبنفسك-ر6غ]

شكراkzbin.info/www/bejne/m17NXnuubNtmpas

[@juanitovonbumblepantz7252]

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.

[@mohammedarif395]

But at last he has mentioned the centrifugal force. I Hope that is enough

[@derimmor]

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.

[@voprais]

@@derimmor It's called a tilting train. "Pendolino" is a specific family of those trains made by Alstom SA.

[@simonm1447]

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.

[@OlgaPlaysMatch-3Game]

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. 😪😪😪

[@KerbalChris]

@@OlgaPlaysMatch-3Game is slants upwards and its called a dihedral to help with roll stability

[@DanSlotea]

@@OlgaPlaysMatch-3Game you have been obviously smoking the wrong stuff

[@yosyp5905]

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.

[@simonm1447]

@@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

[@edgleason8918]

The elegance of simplicity. That was cool.

[@SanthoshSandy1991]

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".

[@itchyvet]

You should have told him you steer the train with the hand brake wheel. L.O.L.

[@zach6867]

Your answer was right too

[@Steamrick]

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.

[@justinsanity501]

As an engineer, simple but effective design like this is what I live for. This is freaking beautiful.

[@sawyerwallin-hb4vo]

Awesome this is why I like trains.

[@Nascarnate100]

This is such a cool video! Educational, while still being easy to understand, and visually appealing, without losing the basis of the content. I love it and I can’t wait to watch more

[@NoIPHU]

So underrated comment. Totally agreed.

[@helomech1969]

I had worked for a major railway from 1999 to 2001 as a heavy equipment mechanic for the equipment that relayed rail and replace ties. I did notice when we relayed rail it was on curves and it was always the outer rail that needed to be replaced. Obviously you don't get full differential capability due to tighter radiuses and I'm sure other factors. But it was also interesting in my observation that curve rails that were replaced tended to be in position longer, meaning a longer period of time between replacement for those rails that were attached to wood ties opposed to concrete ties. I presume that wood ties give a little flexibility opposed to concrete ties. I am in no way shape or form educated in engineering as I'm just a high school graduate with my highest education. Feel free any of you to add to this to explain what I have witnessed during my time with a major railway.

[@philiptong4978]

assuming a heavier train would wear down the track sooner, the frequent outer track replacement could indicate trains were going faster than a turn was designed for, or the bank angle (tracks tilt towards inside of a turn like a dinner plate) was reduced somehow

[@sumanthm629]

Good observations. Glad you observed things closely at work to make logical and reasonable conclusions without going through just the motions. Hope the Engineers listen to these to make better and safer rail tracks.

[@lewis2553]

You are right about the curves sometimes being too tight for the conical shape of the wheel to compensate. The wear is probably from the slippage of the outer wheel against the track when negotiating the turn. If the conical shape could be properly calculated to accomplish 100% of the needed differential action on a particular radius curve, ALL curves would then have to be the same radius to avoid this wear. I doubt that would be possible.

[@chancelindsey]

Your service is very much appreciated, valued and necessary. People like you are the ones actually keeping the world as we know it moving.

[@lewis2553]

@Fred Wills I'm glad you said that it is counter-intuitive TO YOU, because, to me, I see an axle rolling in one direction -- forward -- with two wheels of different diameter contacting the rails on curves. One outtravels the other, giving the differential action, and also, being a larger diameter at the line of contact, it also lifts the train on that side, shifting some weight to the inner wheel. The inner wheel, being a smaller diameter at the line of contact, drops the train a bit, taking on more weight. This is equivalent to to a banked curve on a racetrack or highway. Since the principle of banked curves has been in use for decades, or perhaps centuries, I don't understand why it would be counter-intuitive. Maybe it's because you have erroneously assumed that the torque on the two ends of the axle is in opposite directions. It is not. This is variable differential action, the degree of the action depending on how much the train shifts to the side. But it is within a limited range because the axle is solid. The tractor differential has two separate axles, and either one can outtravel the other by an unlimited amount. You can hold one wheel completely still and let the other go around it in a circle because of that. You can raise one rear wheel of a car off the ground, and yes, you will have torque in a direction opposite to the torque direction on the opposite wheel. But that is a powered axle, and it is a different type of differential system with TWO separate axles and unlimited range of differential action. With trains, it's different. If you had torque in opposite directions on the two sides, one side would have to overpower the other to get movement. The side that was overpowered would then have to slide on the rail. In reality, there is no torque on either side, since there's no drive shaft and no driving force applied to any of the train wheels other than those of the engine. And the drive wheels of that use a regular differential like automobiles and tractors. It's really quite simple to understand, if you just look at it right.

[@sudeeptKJ]

Your simplicity on each topic is awesome

[@sundarrajan9886]

Superb explanation! It has been said that we don't invent principles, principles already exist in nature. We only discover them.

[@DunnickFayuro]

Now for your next video: How do you determine the optimal tilt angle of the wheels, and how it is if it is) related to the maximum turn radius of tracks?

[@jacklincoln7786]

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.

[@kfossa344]

Okay

[@troyt6532]

How do chariot wheels have anything to do with this?

[@caseyb1346]

@@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.

[@friendlynudist2191]

@@caseyb1346 Do you know why Spain has wider railroad tracks than the rest of Europe?

[@kfossa344]

@@caseyb1346 see, now this is actually some interesting stuff. More people need to be like Casey.

[@PranavPandey]

Dangerous fun ever in history 2:25 btw out of fun (Not your kind of 😂 ) Your explanation through amazing graphics shows your pure dedication towards your work ,Thanks Sir!

[@lksout2436]

😉😉⏭️⏭️🏧🏧🏧

[@sebastianbuse4899]

what is camber

[@jimmybagg9439]

I couldn’t understand

[@DipFF_Youtube]

Wah badia

[@ihaveagoal4665]

@Based Madara can confirm.....i have seen biden asking him to write his speeches

[@ZelineZed]

This feels to me like the highest form of overexplaning because it happens to be one of those things that are so evident they just feel so natural and self explanatory. BUT I do recognize that this could just as easily be smth I would not naturally understand and I am still grateful for the explanation. Stumbling onto those small "natural knowledge" gems gives me a taste of what actual genuises must experience when experiencing the world. It is quite astonishing to find that this is like understanding why a cone is more stable on it's base for me yet I struggle with so many other concepts. Blows my mind to think that some things I really can't wrap my head around, are this easy to understand for some others!

[@onrr1726]

Profiling the rail with rail grinders also helps with keeping the train on the tracks as the rail will develop spliters and railhead drift. The inner rail on the inside curve develops spliters and drifts to the in side of the gage in the curve while the outer rail drifts into the out side of the curve wearing down the inside of the railhead. All this can wear down flanges on the wheel sets.

[@medicasclepius236]

I'm interested in the topic you speak of. I'll try to search it but you have any websites on this or videos to suggest I'd greatly appreciate it. Very cool information to know imo Good thing I'm not one to panic. But I definitely would if I was in a remote place in a 3rd world country. They tend to skip on those safety details (at least I would think they would). Does this always explain why most trains will derail on turns if not properly maintained?

[@onrr1726]

@@medicasclepius236 in general it's good practice to get even wear on the track by running trains in both directions on the same set of rails. The big Class 1 railroad in my area CSX dose this with the two track main line. All east bound traffic will run on track 2 for 12 hours and west bound traffic on track 1 for 12 hours. When they change dispatchers the trains on 2 start going west while trains on track 1 go east for 12 hours till the dispatchers shift change happens again. There is definitely some decent material on Rail profiling look up LORAM they give a brief on their web page on what they do. There is footage here on KZbin but most of it is railfan footage. Another company that might have something is Pandral Jackson or Harsco? Not sure what they call them selves now.

[@medicasclepius236]

@@onrr1726 Thanks, most appreciated. Did a little bit of "light" reading on it last night. I definitely look that up.

[@sapper82]

And when you start throwing in "Gauge Corner Cracking" which led to the horrific Hatfield Derailment one can understand why rail grinding is an essential exercise on a high-speed railway.

[@captainkeyboard1007]

I enjoyed this lesson about the movements of the flange wheels, even rolling through the curves of the railroad track.

[@Mystikan]

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.

[@Sweet-bx2ec]

Sure but.....a train doesn't only have wheels....so you can't really make a sharp turn

[@Mystikan]

@@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.

[@Mystikan]

@@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".

[@briantelford8532]

High elevation curves also utilize rail lubrication devices to help prevent premature rail and wheel wear.

[@jerryhong4304]

Calculus

[@prototropo]

The first two points of logic are revelatory--the conical angle corrects the tendency inward, and compensated for angle differential. Wonderful.

[@TheDreamingDriftersStories]

I have never even thought about how the wheels of a train work. I had no clue there would be this much thinking and calculating, involved with designing those simpel metal wheels. Great explanation 👍

[@lksout2436]

👓👓⏭️⏭️🏧🏧🏧

[@magus1017]

How did the algorithm know I’d find this random thing so interesting… it’s really scary. I didn’t even know I wanted to know about this either. But honestly when he explained how the differential action can still be achieved with a fixed shaft connecting the two wheels I was mind blown how simple it was. They’re actually turning at the same rate and not going all wonky like I thought they would. And because of the shape of the wheels one side is actually covering more distance. Amazing

[@zGJungle]

KZbin also some how knew I would enjoy this too, some clever engineering solutions.

[@holomurphy22]

Because most things are interesting when it's well explained So well explained things get liked and thus recommended

[@coltonbabb2705]

During cornering the outer wheel also achieves a higher position, the inner become lower due to the conical shape creating a slight lean toward the inside of the bend thus achieving a positive inward lean, like a nascar track but to a much smaller extent

[@mattburns617]

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.

[@SuperPuggle]

As someone who maintains locomotives, this is all true but for safety there are axle boxes too. Extra safe

[@mscir]

Interesting vide, thanks. - What's the maximum turn radius the wheels can accommodate without slipping? It would be interesting seeing the math that shows the relationship between the max and min diameters of the wheel surfaces that contact the track, and how they relate to the turn radius.

[@sreecharanchintapalli7878]

Yes. I too want to know

[@daxgaming2960]

Rt : radius of turn ; Wt : Width of train ; Rw : outer radius wheel "the small radius" ; Ww : width of wheel ; theta : angle of tapper on the wheel. the condition for no slipping is : (Rt + Wt) / Rt

[@bmw123ck]

And this has to take in to consideration that the faster the train the smaller the "slope" on the wheels. Thus a faster train needs bigger radius curves to turn

[@davidrayner9832]

I don't know the formula to calculate that but the wider the gauge, the greater the difference in distance to cover and thus rotational speed of the inside and outside wheels which is why poorer countries and mountain railways in many countries (poor or not) are narrow gauge. Much cheaper to go around tight curves than to tunnel through hills and mountains. At the other end of the spectrum, UK's Great Western Railway had very gentle curves and was able to use a 7ft gauge.

[@nlaad13]

It can easily take care for curves upto 6degree…. Beyond that curvers are very rare and also speed restrictions imposed….. railways dont have shapers curves as highways thats why differential wheel is not required intrains jst like cars….

[@derekfromtauranga6012]

On a conveyor belt the same situation applies to the drive drum and end drum. They have to be curved with the greatest diameter in the centre so the belt will self centre to track properly. Never thought trains had tapered wheels. I thought the flanges stopped them from going off the tracks. You learn something new everyday. 👍👍👍

[@ashekdahal9436]

I didn't study this in my four years of Mechanical Engineering with loads of content on wheels, gears and differentials Definitely bringing this up with my mates

[@rrrigil]

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.

[@theKiroo]

Being watching your videos for so long, I really wouldn't mind seeing you in person more often in the shots, you have a great room setup there and great personality. But dude, your animations are great, that cup-train wheel transition 😍

[@laurisikio]

We are not here for him but for his understanding of engineering. Besides, the indian accent is way too strong to be understood properly.

[@nagendra27nv]

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.

[@justanotherguy9034]

This is brilliant and yet so simple.

[@sumanthm6038]

I learned more from this video than from my entire 4 years of college. Good work🔥

[@flybeep1661]

I knew this for years since Richard Feynman talks about this in one of his home interviews during the 1970s. Funny thing is, the concept is simple if understood but when I try to explain this to other people for some reason they try to find excuses to match their own assumptions and not the explanation. Most thing I've heard, "trains don't need a differential like in cars because the tracks bend very slowly" or "they don't need this shape because the flanges on the wheels are what keeps it on the rails". These kind of reaction are mostly present with educated people (higher degrees) who consider themselves knowledgeable on all and every subject possible.

[@asneakychicken322]

Sounds like a proper Dunning-Kruger effect, they know enough to be confident but not enough to know how little they know.

[@Ronnymikkonen2686]

But that doesn't explain it!

[@lennartstockl5826]

You need to understand vectors to understand this properly and the basics of vectors are already high school matereal that I've seen people struggle with. Not everyone is proficient enough in physics to understand it immediately.

[@Ronnymikkonen2686]

@@lennartstockl5826 I understand.

[@howieduin915]

Educated beyond their intelligence. I see it too often.

[@tytn9978]

Thank You! At last, a question I've had about trains over the years has been answered in a way that i can understand. Now the ability to go so smoothly around curves makes perfect sense! The other question I have, living in a country that has lots of snow: how do the wheels stay on the track as the front engine uses a snowplow to sift snow to either side? I know with a car how easy it is in a snowstorm to slide off the pavement onto the shoulder, but I don't ever hear of trains doing the same off the track!

[@claiborneeastjr4129]

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.

[@surferdude642]

Thanks, I never knew that, I thought it was just the flanges that prevented derailment. I guess it would also reduce friction. It could also reduce traction when climbing, no? Especially, when wet. I realize they spray sand on the rails to increase traction.

[@makismakiavelis5718]

I think traction in trains is provided by their sheer weight. Even so, most trains are unable to climb steep inclines. For this special trains fitted with cogwheels underneath the chassis and special tracks fitted with chain and pulley systems are needed. But I am not sure.

[@danielcarroll3358]

@@makismakiavelis5718 The track is fitted with a rack, an unrolled gear that engages the cogwheel or gear under the locomotive. Flanges are secondary devices to prevent derailment and are necessary on especially sharp curves. You can hear the squeal when the wheel skids on the rail and the flange rubs, especially with trams or streetcars on street railways. In cases where mainline railways must have very sharp slow speed curves they will use a flange oiler to reduce the problem.

[@makismakiavelis5718]

@@danielcarroll3358 Interesting. Thanks.

[@1963TOMB]

@@danielcarroll3358 Sometimes the uses of a 'check rail' is also used to ensure the wheel stays on the rail on tight curves and at points (switches).

[@danielcarroll3358]

@@1963TOMB True. Also on bridges and such you will see another set of rails inside the running rails to keep the train from falling off the bridge if it *should* derail.

[@ninjabaiano6092]

I do like to point out that this shape also makes it possible for trains to keep running even if the tracks are not perfectly at the same lenght as normal.

[@cyanidesky8170]

Keep up the good work! I wish such videos were there at my school time. It would have made learning more and more enjoyable. Engineering keeps inspiring me

[@kevinpatrick8788]

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 .

[@orbismworldbuilding8428]

Basically: The wheels are shaped that way so they fall into eachother towatds the center of the track The turn thing works because the cone has varying diameter depending where you are on it, and the speed of the wheel rotating depends on how wide the wherl is

[@nisios]

I think this video was short, informative and well made. Your comment resuming it is pointless.

[@shyambuddh5546]

@@nisios it could be useful for the person themselves

[@orbismworldbuilding8428]

@@shyambuddh5546 yes

[@A_Ereira]

@@nisios Nah, I found it helpful to read another summary of it. Things being explained in slightly different ways makes it more understandable for me.

[@universalstudios13]

Very well explained mate.

[@paulrandolph8469]

This self-centering sounds similar to the way dihedral wings self-level the plane when it tips--vectors and perpendicular angles.

[@michaeldosoo5994]

Thanks!

[@petra_kalbrain4426]

Never thought about this before. Never really cared to know. Now that I know, it’s a fascinating piece of “useless trivia” to have at my disposal for party chit-chat. Thanks for the great & clear explanation! 👍🏻😎👍🏻

[@robertvig3227]

Good explanation. :-) Just one thing makes harder to understand: you call the right wheel the left considering the movement of the train. I like naming the wheels from the driver's point of view. It's conventional throughout the vehicles.

[@chuckgilly]

I work on vehicles, however, the driver side does not work because there is both right and left-hand drive.

[@philr696]

But you are still facing the same direction.

[@brumbywal8432]

I was looking for the negatorians, smack on I've found'm.

[@KerbalChris]

The conical shape does have a bad side, it sets the trains top speed. It’s a cost for having increased stability, but the train will wobble if it goes too quickly

[@snowstrobe]

The wheels on the high speed trains are still conical, but not to the degree of other trains. This is why high speed can only realy be used on tracks with minimum curve, since any doubling of speed requires a quadripling of a curve's radius.

[@sublivion5024]

@@snowstrobe some high speed trains will havs less conical wheels, but most just use yaw dampers

[@reggiep75]

But this is why *properly planned* fast train networks limit their turns and build in a straight line as possible and just dig thru anything in the way.... like a mountain. 'Out of the way, we've got a fast train track to build here!' 🚅🚄

[@sublivion5024]

@@reggiep75 No, minimum radii and transitions for high speed lines are set for passenger comfort, not normally the capabilities of the trains

[@reggiep75]

@@sublivion5024 - And my point completely encompasses yours as I mentioned nothing of train capabilities. You did that to illustrate a moot point that is already given as is passenger comfort 😐😑😐😑😐😑😐

[@ShineWithShimmi]

Explained with Animations" impressively simplifies complex concepts. Clear explanations, captivating animations, and enthusiastic narration make it a must-watch. Real-life examples could add practical context. Excellent job! Recommend for a concise understanding