How trains actually Turn ? | on curved rail track.
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- Опубліковано 5 жов 2022
- #railway
train wheels are slightly conical in shape.
this helps to turn the wheel along the curved rail track.
In this video , learn the concept of how it works. - Авто та транспорт
Never knew that the shape of the wheels and the tracks were that important. Always thought just the flanges were responsible for the steering. Very clearly explained for me who has no degree in math. Thank you👊🤗
Fun fact: when a train traverses a sharp curve at high speed, it is not uncommon for the flange of a wheel to contact the side of the rail. To minimize the wear and tear on both the rail and the wheel, "flange greasers" are sometimes installed to apply a small amount of lubricant between the flange and the side of the rail.
track oil feels almost liks blinker fluid
This is taught in a 2nd yr of Mechanical Engineering in all good Engineering Colleges.
It's something obvious
@@tapanprakashsen3873 Could be. I'm a musician😉
This is a broadly correct but simplified explanation. Some extra details: the wheel profile is not really semi-conical; it is a complex hyperbolic transition into the flange. But at first glance it looks like a conical shape. The inside camber (angle) of the rails is necessary to prevent the "conical" shape of the wheel set exerting an excessive lateral force onto the rails, which would otherwise tend to be pushed apart. Two interesting effects can actually be heard; one is where the train has come to a near standstill on a curve with superelevation which is normally designed for higher speeds. Then the wheel-set is not sitting in quite the right position on the track, and one wheel starts to slip with stiction, giving an audible shuddering noise. The other audible effect is where the curve is so tight that the flange comes into action: this results in a sharp metallic (& loud!) squealing sound. This is usually at slow entry & exit sections into / out of stations and switch yards. To minimise flange wear, automatic grease pump stations on the track are often employed at these sections, which only grease the _inside_ surface of the rail where the flange makes contact, but not the running surface of the rail (you don't want grease on _top_ of the railhead).
Exactly. There is a curve between the tread and flange which helps centralize the wheelsets.
indeed, but in previous steam, they hadn't understood that yet. Like gears, involute was pretty recent - the pressure angles changed in 20s and then 40s.
Exactly. I have said this many times.
"The Loop" in Chicago is really loud as the trains negotiate ridiculously tight curves.
I've tried to explain this so many times to my grandsons and they never seemed to grasp it. Showed 'em your comment and finally they understand. Many thanks!
👁 👁
👄
Wonder how these massive steel wheels are quieter than car tires moving over steel tracks at 160-200 mph. Might be interesting to hear a train engineer give detailed explanation why high speed train is relatively very quiet from inside. Freight train moving 30-40 mph is very noisy standing outside. We are talking about bullet trains.
In the corners they make very much noice
@@J2gt yeah, *ALOT* of noise
No, my friend, they are not quieter than cars...
@@J2gt only if the train is badly designed or extremely old, like NY subway
There's less friction due to smaller and slicker contact surface. They do make a lot of noise when rails are not welded together though.
That’s as long as the wheel profile matches the curve radius. Once the radius gets tighter, the flanges come into effect and you will hear flange squeal. Also, the flanges are what guides the trains through turnouts aka switches.
This is why flanges must be at a certain thickness. A thin flange can split a switch, causing a derailment.
My dude, you post sick bass AND know about traction systems? Pretty cool
@@abhinav7885
I make Bass music but also into everything about the railway system. 👍🏻
@@Bassotronics what a legend
@@Bassotronics I had a question, what do you recommend me to start getting in to railway engineering? I am an EE and wish to work in this field.
6:15 The solution in short: As the railway turns (let's say to the right), the rails slightly move to one direction (to the right), but the wheels want to roll straight because of their momentum. As the wheels are semi-conical, the contact position between wheel and railway is shifted (to the left) and that creates a semi-conical rotation, where the wheel automatically roll to the side (to the right) and takes the curve.
Good explanation. Different people have different ways of expressing the same point. We need to appreciate the intention.
You sound as bad as the video.
Not forgetting that the inner wheel has to compensate for the shorter distance travelled while being on a fixed axle, and the outer wheel travelling a longer distance on the same fixed axle during bends.
Thank you. I found it a little hard to understand with the robot- like voice in the video
rather than thinking in terms of cones and conical things- think of it as modifying the operating radius of the wheel. a smaller radii on the inside wheel is going to make the axle turn in the direction of the track curve.
Always knew that the wheels were slightly conical but this demo makes the actual physics of the conical shape easily understood, before when I was explaining that train wheels were slightly offset the ones I was talking with couldn’t really believe me but now I’ve got something that explains it better than I can
Fool
there are no 'physics' unless the wheels are turning- the shape of the wheel-treads are designed to operate using differing radii in curves and this also illustrates why gauge accuracy is so very important.
It's bloody 2:14am, and here I'm getting some science lessons from YT og recommendations.
When I was a kid, I did a lot of research on this.
Out in the “road,” the wheels act like this, steering themselves.
I had hung around with a switching crew for a summer.
The most incredible parts were where the curves were so sharp, that the wheels squealed and the flanges were taking over the job.
I always found this fascinating to the point that had some railroad had taken a chance on me, I would have made a career out of it.
Well, I got stuck in a construction and trucking job where I was sometimes working in the worst of conditions.
They had no clue.
Their loss, not mine!
i always wondered what the life expectancy of the track and wheels would be especially in the turns. i had a whole career 40+ years working as a lineman for a municipal power company but i have often thought that in my next life i would work for the railroad like in track maintenance and construction or perhaps even driving an engine. i think it would be a good calling for guys to get into. one other thing i've always thought of is the fact that they have turned a lot of the old railroad beds into bike paths which is good but thought they would have been better served if they had turned into use as public transportation between towns and without track but on tires. just an idea.
very cool. i'm envious!
@@steveperry1344 I had considered that, too,
It’s actually a good idea.
But, I did the research as a kid, and thought, maybe a few concessions?
The Michelin brothers came up with a flanged rubber tire that rode on rails, just like todays trains do.
They didn’t like the steel-on-steel noice while traveling around France.
There were a lot of other issues as well.
But, the fact that the grades are still there.
Sure, some of the bridges would need to be replaced, but the surveys wouldn’t be needed, and it wouldn’t be hard to take control of those old grades again.
Who knows, maybe we would have floating trains above them in the future?
@@dangeary2134 the flange was not made of rubber in michelin's micheline scheme- it was steel augmenting an inflatable traction-tire configuration. if it lost car- the wheel's base contours and flange took over. budd used the design back in the 30's after goodyear's wheels repeatedly derailed in testing.
@@tommurphy4307 actually, the later versions were.
My college thesis, I did a lot of research on the subject.
As it turns out, a layer of rubber over a piece of steel that is used for traction tends to either separate, or suffer internal damage, splitting the rubber. Inflatable rubber tires, even for trains, did work.
After the flanged rubber wheel was developed, they suffered from wet rails, and they slipped.
They added sipes to the tire that simply went crosswise on the tread area.
They had the effect of being a squeegee for the following tires.
The sipes also had and unforeseen effect on the tires.
They didn’t wear out as fast.
The Michelin brothers did some really serious development to rubber, even before tubeless “clincher” tires and rims were developed.
An amazing animation and clear explanation. I've never thought simple - actually, as I've learnt today, by far not so simple - rail tracks and wheels require this much sophisticated design.
Thank you so much for this video. I've found it just by accident but now I'm looking forward to watching the previous ones, too.
I was working on the central line (London underground) when they got the new trains, the wheels were designed differently to what the old stock ran on which resulted in the tracks getting worn... Large sections had to be shut down at a time to replace the track. We weren't privy to the possible upgrade of the wheel set up but this video is interesting.
Now I have learned something I didnt know anything about, and that I have never even thought could be an issue in rail engineering.
Thank you!
Well explained , shows us that it was almost impossible to find out by ourselves how that all worked actually ! and it started already in the nineteenth century with all the machines needed to produce such fine pieces ... wonderful !
Who was the genius who developed train wheels shape in the 19th century? We all learned about the first locomotives, but nothing about wheel and track profiles! Till you posted this - Thank you
@@portobellotent Flanged wheels go back to the 1600's. Don't know about the conical wheel shape.
Such a video voiced by an actual human with a firm grasp of the English language would be much appreciated.
Very nicely explained. Many times I wondered how rigidely connected wheels, in the absence of a differential manages to negotitate curves without slippage. Your clipping cleared all my doubts. Thank you sir.
im agree with u sir.
True. Agree. I thought the flanges did the job.
tx,
Im not sir, no need of saying sir.
We all humans, im Darme,from srilanka.
Im proffessional engineer, in electrical
Cheers
there is no such absence- the entire wheelset acts like a differential due to the wheels' varying radii.
They slip. They always slip.
good vedio.
Explain very well.
Thanks for ur prasantation.
Keep going.
Thank you for adding what would happen at the end if the smaller conical shape were on the outside rather than the inside. I'd been trying to imagine it as you were describing the correct configuration.
Thanks to the animation creator and who explained the physics. Excellent presentation.
i started my engineering career with rail support maintenance and was so surprised as how this occurs. Cars and locomotive trucks must be re-turned to put that profile, as well as the rail. specialized equipment is used periodically to regrind the rails. amazing!
really? even 5-year-old boys who played with lionel post-war trains knew that- i was one of them.
@@tommurphy4307 cool - my dad was not big on mechanical items so sadly i only saw trains in displays.
I don’t know why i am watching this at 3am but it’s quite fascinating to understand rail working
Lots of good information but I'm left with questions (in case they do any revisions). The graphics for the force vectors are all drawn by someone who didn't understand that the length of each vector is proportional to its magnitude. The big resultant should be the diagonal within a rectangle and the horizontal component is the short side of that rectangle while the vertical component (resisting gravity in this case) is the long side. Next, I kept asking what keeps the wheel from getting so far to the side to have the flange touch the rail to make that squealing sound we all dislike (the sound that every Bostonian at Gov't Center hates). The video leaves the stability question only half-answered. Then there is the purpose to all that random, irregular thump, thump, thumping. Also, was this written by a person who made dozens of grammar errors or a computer who writes, mostly correctly, what it hears - leaving those errors untouched?
people who REALLY understand wouldn't even have to draw anything... but that would take mechanical and spatial aptitude. maybe some strength of materials knowledge would help.
What an amazing explanation! The graphics you created specially to explain the mechanics behind the design of rail tracks and wheels is so very effective and appreciable. The way you have explained the whole thing is so easy to understand. This is how complex concepts need to be taught. Three cheers!
True.
a picture is worth a thousand words.
You give the basics, but it's more involved than that. Without restraints on the wheel set, the forces that tend to centre the wheelset tend to cause it to overshoot and then hunting occurs where the wheelset shunts back and forth laterally. This phenomenon was extensively researched by British Rail scientists in the 70s and the science of self steering established. Up to this point it had never really been investigated properly. It then became possible to design the wheelset suspension to remove the hunting and for true self steering to be established. Eventually, it was found that the wheel flanges had rusted on the inside as they had played no part in steering the vehicle ! The BR scientists nicknamed them "the crash barriers". Of course, once the curve exceeds a certain value of "tightness" as in yards and sidings, self steering is not possible, and the flanges guide the vehicle accompanied by much squealing as wheels skid on the rails.
I completely understood what you said. What I was wondering was, when you design an entire railway system (say for a country), don't you also take that into account? In India our railways are not only nationalized, but we just have a few types of bogie/coach designs per track guage size in operation. Therefore, once the wheel base and axle width is set, it would be trivial to figure out what is the minimum curvature that a particular bogie configuration can move over without its flanges contacting the rails. So why do railways design their systems such that the flanges would intentionally rub/slide A LOT as the track curves? Besides the corrosion issue you mentioned
@@quadrannilator The cost of the infrastructure would be far greater if a minimum curve radius was defined for the routes, so it's a matter of balancing objectives. Our new High Speed 2 with a design speed of 250 mph has very large radius curves, but the trains still have to negotiate track at stations and depots. Here is a typical piece of line to be built
assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/532883/C223-CSI-CV-DPP-030-000003-FPD.pdf
Pretty straight, eh ?
The line is proving very costly to build
@@frasermitchell9183 Hmm, I think I understood. The minimum free curvature is too large. Accepting less curvature for wheel slip is a better compromise vs. ideal curvature
I think what you are referring to is hunting oscillation. In the most common wheel design it only becomes problematic above 160km/h.
Many bogies, esp. on high-speed passenger trains, have dampers fitted between the frames of the car and bogie that limit the speed of bogie rotation and hence dampen the hunting. Worn-out rotation dampers can often be identified by a hunting bogie. These systems still have a resonance frequency and hence they can only be designed to work efficiently within certain speed limits.
I'm 70 years old. Never to late to learn. Excellent video.
I live near railroad tracks, often walk near them and never noticed all this. Thanks.
You could have learnt by lying down between the tracks, and watching the wheels when a train went above you, safely. 😄👍
@@shreeveda 💀🤣
Lucid explanation...very well done...now I understand the Amtrak lurching and long period sway at high speed. Good stuff!
now explain the norfuck-southern approach...
The track system is basically the same since it started. That says a lot for the inventor.
The inventor is probably still getting the paychecks slingshotted to heaven.
Been wondering about how this works for years. Puzzle solved. Thanks!
I understand the differential effect and camber angles in automotive steering. This video makes complete sense, very good!
Excellent explanation. I used to know different explanation, you have clarified with correct information. Thanks 🙂
Keep making videos about train stuff.. I love these
I knew about this but I had trouble explaining it. Now I can direct folks to this website. Many thanx!
It is one of the best explanations i have ever encluntered on this topic. I wish they would teach the same way in school, colleges, and universities. Thank you very much for making this wonderful video
The ratio of triangle (sin and cos) explanation finally made me understand! Assume hypotenuse is constant (non changing). Any angle change set by the wheel at that point in time changes the horizontal and vertical (ratio of opposite and adjacent over hypotenuse). But since hypotenuse is constant only the other sides change length and the length is equal to the force!
Ken do attitude
precisely why its better to think in terms of varying wheel radii and their effect on the steering of the truck, as well as how that steering effect relates to the curvature of the rails.
@@tommurphy4307interesting indeed, so the change in length (force) corresponds to a change in contact of the rail to the differing diameter of the wheel shape?
Very nicely explained!
Thank you very much!
Sounds like Kevin Malone narrating. “WHY WASTE TIME SAY LOT WORD WHEN FEW WORD DO TRICK”
Terima kasih kawanku telah berbagi informasinya
Great video and very educational!! Thank you! 🙂🙂🙂
Very interesting and makes sense. Can or has someone explained the cross anchor bogie which improves curve handling.
even a blind can understood clearly.... thank you.... well described... ❤️
Excellent presentation. Very well explained. I learned something new today. Thank you.
This channel deserves 10M subs
this does a good job of explaining this but I wonder why it is so difficult for engineering types to use articles properly.
Haha, I was thinking the same thing. The animation was great, but the narration was horrible. Don't these UA-cam creators actually read their script before getting the robo-voice to read it, and then don't they actually listen to the video themselves to avoid getting embarrassed about all the grammatical mistakes?!
A lot of eastern European languages, like polish or russian, do not have articles. Speakers of these languages almost never used "the", "a" or "an" prior to learning english, which makes it difficult to understand their actual use and spot the errors. The mother tongue of the creator of this video very likely does not include these articles either. That doesn't mean the video wouldn't benefit from some proof-reading. I also found the mistakes distracting.
It's from India, creators are (likely) Hindi speakers. No articles, little plural distinction. The narration appears to be STT.
That said, English is very widely used in India, and there should be no trouble at all finding some average joe who can clean up most the grammar. The channel has very few vids as yet; perhaps they will start tidying their presentations.
very informative and very beautifully explained. never realised that the flanges are slightly conical. thank you.
Thank you for your most valuable lesson about the act of a railroad train. It convinces me more that railroad trains are not driven: they are only operated by engineers and other train operators. This lesson teaches me how flange wheels make slivering sounds when the wheels turn according to the bend of the rails.⭐🌟
the vector components at 4:20 are typically demonstrated by drawing a rectangle with F as the diagonal, and the components as the height and width of the rectangle.
Not only demonstrated. They talk about cos Angel and show random length.
I noticed that too. The blue arrow is the "resultant" force and only slightly longer than the vertical arrow. The horizontal arrow is shown way out of scale: it should be very short. Otherwise very nicely done.
This seems to be only partially true. For certain, the semi-conicity of the trail wheels helps keep them centered on the rails without the flanges doing all the work. But the part of this video that tries to describe both wheels on an axle as acting purely like a large truncated cone is at least somewhat specious. Even if this effect was entirely accurate, it does not explain how the wheels always follow curved tracks regardless of other forces (not mentioned in this video). Also not mentioned is that on modern trains, each bogie also steers passively, and the flanges definitely help the bogies reorient themselves to keep the wheels best aligned with the rails. In short, this video makes a good point, but the overattributes the affect as if it is the ONLY thing contributing to the train's steering.
the flanges don't do a damned thing unless there is a sharp curve such as what is common in yards. the wheel treads and flange-radii curves do it all otherwise.
Excellent - semi conical shape wheels - railway track -rails trigonometry mathematics calculation -centrifugal force - application - simply superb
U explained me a 200 pages book in 8 minutes . You're Amazing bro, Try to make people understand everything in this world keep it up 👍
Irrespective of a few extremely minor flaws...it's an excellent explanation on something I did not know before 👍👍👍👍👍
Whomever figured all this out in the first place was a genius. I've loved railways all my life and I just learned this today.
this should be taught in schools...very good. thanks
Thank you for explaining this principle in such lucid and easy manner. Much appreciated!!
No one thought a train had a steering mechanism…. 0:05
Was this known at the outset of rail roading, or was it developed through trial and error?
I imagine that the flange on the wheel - must have always been there.
This would be a great Test Question to solve in Class.
Always enjoy see practical examples of math/trig in the real world. Nice work.
Genius old engineering! Thanks for an excellent explanation!
very clear explanation. Is the same principle at work in two-wheeler counter-steering?
I think that counter-steering has effect on the centrifugal force. The shape of the tires ( conical as the train wheels) are not as important. But this is purely a thought, not scientifically tested by me😉
The counter-steering effect arises from the gyroscopic properties of the front wheel of a bicycle or motorcycle. To make a right turn on a motorcycle, for example, you exert a torque on the handlebars to the left and gyroscopic precession causes the front wheel to lean and turn to the right.
The animator blew it when showing the vertical and horizontal components of the perpendicular force. The horizontal were typically shown much too large and the vertical too small.
Clearly!!
In a mathematical sense that's true, but for illustration purposes he did the right thing.
Picky picky ! A Very difficult technical subject , which the animator has done an excellent job of explaining n !
I am curious as to what Animations you have produced ?
@@tennwilcox8663 aaaŵqqqssssaaaaaaaaaåååååeweeeèrrrrrrrrrrrrŕŕrrrŕrrrrrŕrrrŕrŕrrŕrŕrrrrŕrrrŕrŕrrrrrrrrrrrrrrrrrrr
The vertical component should be the static weight. So yes, it seems the vertical force is larger
MAN that was a LOT of math!!!! I took train wheels for granted, but now I wonder who in the world came up with all this knowledge. I mean it is ridiculous. It’s a “simple”…wheel but it’s not! SOOOOOOOO cool to even get a GLIMPSE of the engineering involved!
Fantastic! what a wonderful explanation! thank you very much! I understand perfectly!
wooow
What you don't mention is that the wooden ties on curves are subjected to a lot of wear. My college professor in Wood Products Engineering used to say that the Southern Pacific railroad didn't use creosote treated ties on their curved sections because the ties wore out so quickly from stress and vibration and needed to be replaced so frequently that the extra cost of treatment wasn't worth it.
Railroads haven't used creosote soaked ties for decades do to them harming the environment. I've replaced thousands of ties, and the only creosote ties I came across was from the 1950's.
@@SmokinOak nyc still uses creosote ties
yes but that also goes back to the days of steam-powered locomotives and track fires. many roads didn't use creosote ties just for that reason- especially in the deserts and other dry areas. i think the SP knew a lot more about track and trestle fires than most roads did.
@@SmokinOak really was economically-motivated since coal has shot up in price. the roads and creosote production relied heavily on coal back in the day but now many roads don't even use wood ties.
Excellent animation! I learned this design for the first time. Thank you!
That was mind blowing explanation i haven’t seen before 👏👏
I like your exclamations very much . they say using rails instead of trucks to transport goods. I think I heard once that once the wheels are moving it will keep going and slow down eventually. In that case it will uses less fuel pre mile. Doesn't need as much fuel because these heavy structures won't stop so easily just like a bowling ball.. could make a video and possibly to tell us what forces are at play there. Just started watching like your programs very much. many of us appreciate it
The effect you are referring to is rolling friction or rolling resistance. It is related to the amount the materials deform during the action of rolling. The rolling friction of steel on steel is far less than a rubber tire rolling on asphalt or concrete. It follows that rail is more efficient than using trucks as far as fuel required per mile is concerned.
If they are going to take the time to explain the concept through detailed graphics and animations, why not put a little more time into getting the grammar right and maybe using a real human to provide the narration?
0
Cool to watch I built wheel sets for trains for a living. Very cool.
This is good old engineering explained with today's excellent graphics. Hats off to those engineers from the Industrial Revolution.
The singular vs plural and the lack of using articles in the text of this was very distracting i realize it was a computer generated voice but damn
The train knows where it is at all times. It knows this because it knows where it isn't.
Excellent information.
fascinating. very well explained
There is no such thing as centrifugal force. There is centripetal force, which is tangential, not radial. This is high school physics. Rails are not tilted inwards: the tops are ground to match the conicity of the wheels. When you said 'we already said ...', you hadn't. You didn't mention that the bogeys can swivel w.r.t. the carriage. You left out about a thousand 'the's. Please don't perpetrate misinformation or illiteracy.
I would say there IS such a thing as centrifugal force: it's the reaction to centripetal force. You know, action/reaction. Also, I would say that centripetal force is radial, not tangential. Otherwise, you comment is spot on.
@ClarenceGreen You just failed high school physics. The reaction to centripetal force would be back down the track where the train came from, not at ninety degrees. If there was such a thing as centrifugal force, a derailed train would fall off sideways, radially, instead of ploughing straight ahead, tangentially, as it actually does. Look it up. You are talking arrant nonsense.
@@EJP286CRSKW Centripetal and centrifugal forces are both radial, neither of which is "back down the track." I guess it's a good thing I did not take physics in high school. Did you?
@@clarencegreen3071 Centripetal force is tangential. I already said that, and I also said that the _reaction_ to centripetal force would be back down the track: not the centripetal force itself, which would (still) be tangential: a distinction which you don't appear to have grasped. Yes I did take high school physics, and rather more besides, and I'm not surprised in the slightest to hear that you didn't.
And if centripetal and centrifugal force are both radial as you claim,what is the difference between them? You don't seem to know much about it.
@@EJP286CRSKW While I did not take physics in high school, I studied physics for nine years beyond high school (PhD), taught physics and electronics for 33 years at the college level, and wrote a rather successful textbook on introductory physics: Technical Physics by Clarence R. Green, 1984. You can check it out.
Are you a troll? What is your game? In any event, I'm out of here. This is just silly.
Interesting vidio i do understand now how it works realy...... Omar from mombasa kenya.
Wonderful friend and good explanation.thamk you
Fascinating , now I'm gonna research Conics thanks !!!
Very informative and simple animations. Really helpful, good job 👍🏼
Wow! Best builder I've ever seen just absolutely amazing
Purely what I wanna be and how I wanna be skilled in life !
You're the man that's so good just perfection
I love it!! Cheers
I feel like I was just taught railroad mechanics by an Indian. Thanks Chief!
Amazing that the design hasn't really changed for more than 100 years.
just like a GM product....
Very useful and important session ❤❤
Very good excellent explanation as well as animation.
So wonderfully explained with beautiful visuals..Many Thanks pl
A Lovely engineering systems,
Thanks for the info. Was enlightening...
Excellent demonstration and explanation .Thank you,Sir .Vetri South Africa 🙏🇿🇦🙏
Such a clever design, I'm sure nothing bad could ever happen
The animation is super that anybody can understand easily, Railway Engineering is my favorite I like it from my childhood my father always took me to railway line and everything stated practically, I miss him always May Allah give him on highest position in paradise aameen❤❤🙏
Flawless explained!
Thanks
Wow! Awesome.
Today I learned a new thing about rail.
Good and scientific explanation. Never thought about that.
No words 😂😂😂😂 amazing views of railway wheel mechanism
Very comprehensively explained. Good job. Thanks.
Good presentation. Now understood 100%
Excellent narration. Completely understood the design. Thanks a lot.
Fascinating. Incredible.
Good explanation 👌👌💐💐💐
That is very interesting I always was wondering how a train would go round a curve but this was explained very well thanx very much 👍🏻
Very informative video thanks.
Amazing explanation.