Sorry for the lack of actual F1 cars in the intro! Turns out, very hard to license footage 😄 The finale for the railroad series is now on Nebula! nebula.tv/videos/practicalconstruction-installing-a-water-main-below-railroad-tracks?ref=practical-engineering
Doing anything with Formula 1 is a recipe for either getting hosed for way too much money, or for having their commercial rights holder come after you with bogus charges of copyright infringement. Ask me how I know 😅
Before I watch the rest of this video, I hope you address the important and often overlooked fact that trains don’t have steering wheels. OK, let’s roll the video.
I was a location manager and had a retired train engineer working for me. When I was having a "challenging" day, Brad would see this and say, "David - How do you start a train?" and walk off. One day, I stopped him and asked him what he meant by that statement. "There is no locomotive set that can possibly pull a mile long train from a stand still. The locomotive pulls the first car, which pulls the next car, which pulls the next." The slack in the coupling is crucial to allow this 'chain reaction' to occur. He shared that sometimes, with a green engineer, they'd pull into a stop to change crew while under power, taking all of the slack out of the couplers. No go. The solution was to back the train a distance to re-create the coupler slack. So, the life lesson was, if you have a big challenge you're dealing with, find the solution in a series of small fixes rather than viewing it as one big problem ... one car at a time.
Hmm.. "How do you start a mile-long train from a stand still? You take the 'R' out of 'rail' and the 'F' out of 'way'." "There is no 'F' in 'way'." "Exactly."
I think you've misunderstood what was said, you don't back a train up to increase slack before starting, and indeed taking any single bit of rolling stock from 1kph to 2kph takes more energy than taking it from 0kph to 1kph.. common practice on the rail line is to creep forwards in low throttle notches till the rear of the train starts to move, and only then add most of the power, otherwise your being very rough on the rear couplers with all that inertial jerk (there are springs in all couplers but the locomotive to help reduce it, and this will actually cause a stopped train braked only at one end to "equalize" very slowly on low grade track), and on bigger trains will break them outright. But "how do you start a train" is still the correct saying, because it starts slow, you don't feel like your doing much and if you kept going at this rate you'd never make it in time.. but you keep going and as you keep working on the problem you get the means to apply more force and solve the problem faster.
I work for Wabtec (former GE Transportation), we build freight locomotives. The sheer weight and power is unbelievable.. they are truly an engineering marvel.
Nah wabtec would likely drop support for legacy loco platform like C20EMP or slightly new CM20EMP. I hear some parts difficulty for these type. They would pushing GEVO to everywhere
Here's a good way of putting it into perspective for people: Most people see UP's Big Boy as some kind of measuring stick for locomotive pulling power, but it's effectively 2 large steam locomotives permanently connected to form a single huge steam locomotive, and still has about 30,000lb less continuous pulling capacity than a single ES44AC.
Tell Wabtec to stop BULLYING its way into California's trains. Taxpayers in California should use the OPTIMAL system for signaling. NOT just Wabtec because Wabtec is American. You can't preach FREE MARKET ANARCHY i.e. CAPITALISM when it benefits you, but then push ANTIFREEDOM BIG GOVERNMENT NATIONALISM PROTECTIONISM when FREEDOM to choose superior European designs is not in your favor.
starting with "Formula One is..." while showing Indycar is a really good way to get a lot of people up in arms. 😄 But clearly not as many people who seem to read this comment as some sort of insult, indictment or judgement. Ya'll must be fun at parties. Lighten up 🙄
Excellent video, Grady! The "Creep" demonstration was wonderful. This effect actually leads to one of the biggest wheel defects we experience in the railroad - shelling. The creep and deformation actually causes slip dislocation motion in the grain structure of the steel, and atoms start getting peeled out of the wheel, and thrown off - resulting in shelling, which is essentially a "missing chunk" of wheel. Also, Steam Locomotives actually *do* have tires! Different hardnesses as well, depending on the size and weight of the locomotive. They're really neat. The wheel on a diesel locomotive is a much simpler, and standardized part that can just be replaced; so the whole wheel just gets changed out; but with a steam locomotive and their various wheel sizes, castings, etc. - it made sense to have a dedicated tire to replace, instead of a complicated casting.
My grandfather was a machinist changing treads on steam wheels. Not just slip, but out of round because of connecting rod. I thought new wheels had hardened 'treads' that could be resurfaced on a lathe if not too worn.
I'm sure Brady knew the cars at the beginning were not Formula 1 cars, because F1 is very protective of copyright, and he didn't want to deal with the headaches.
@@kngofbngbut he was talking about something relating to F1 cars. I don’t see the problem, he just needed a visual aid, and he got one. He could’ve drawn a F1 car on a whiteboard and it would’ve done just as well.
I mean he could use an ai generated image or video of f1 to gray area out of copyright if he really wanted an f1 car 🤷♂️ but i agree, saying "race car" would have been a better choice.
Was a tanker in the Army and this principal reminds me of how tank track moves. You'd think that the tank track, rotating but laid down stationary, under the tank wouldn't move until the rear end of it gets lifted and starts moving up then forward only to get laid down again, in a cycle. The fact is, when a tank is really hustling, all 60+ tons, the track thats in contact with the ground, which may appear not to be moving, is in fact sliding forward with the tank, slightly but evidently. If you watch closely and see video of a tank moving quickly, especially over a hard surface like pavement, you'll notice that the track on the ground is sliding, "creeping", forward as the tank moves. Pretty cool physics going on there too.
Hard to imagine a solid steel wheel stretching and effectively increasing the size of its contact patch to obtain maximum tractive effort. Its actually genius. Once the tractive effort reduces, the contact patch shrinks to its normal size and rolling resistance becomes minimal at cruise. The more I learn about trains, the more respect I have and the cooler I think they are.
Isn't it the exact opposite? Contact patch has two parts, one under static friction (stick), and one under dynamic (slip). Stick area has higher coefficient of friction, slip has lower. Each carries its own portion of the train's weight. But when we try to increase torque to get more tractive effort, stick area decreases, so slip area carries more weight - so shouldn't the effective friction coefficient only go down?
I don't think it's the _size_ of the contact patch that provides the extra friction, it's the _shape,_ which alters the effective coefficient of friction. As friction is weight × coefficient, notice how there's no contact area term in that equation at all. All else being equal, _the area doesn't matter._ Think of it this way: with bigger contact patches, the friction is spread out over a larger area - but this is _exactly balanced out_ by the fact that the (gravitational) force pressing the contacts together _is also spread out_ over the same larger area. Of course, in the real world, all else is not equal. A certain size and number of wheels or tires _can_ be helpful. But it's not _directly_ from the size of the contact area. I think the reasons are: - Greater contact area, lower pressure. (Pressure, e.g., pounds per square inch, is weight divided by area. So, for example, a 3000-lb vehicle with 30-psi tires will have a total contact area of at least 3000 lb/(30 lb/in²) = 100 in². If contact area is smaller than that, tire pressure will need to be higher.) And at lower pressure, rubber tires deform, increasing their coefficients of friction. (The deformation of the train wheels is the thing you're talking about as well.) - A large contact area is good for averaging out the variable friction of a real-world surface (e.g., ice, oil, gravel, painted lane stripes). - (Not related to friction, but) a lower pressure also means the wheel and the road don't have to be engineered for a higher pressure.
4:10 Rolling friction (or rather, rolling resistance) isn't the same as adhesive friction. Adhesive friction is GOOD for rolling, it's what defines it. Rolling resistance is bad, unless you want to brake. This is the distinction people often forget to point out, which usually leads to confusion. Weaker adhesion doesn't help you roll better.
Excellent point - underrated comment. Engine wheels have torque applied to get them moving. Rolling stock* wheels should have minimum turning resistance * there is a clue in the name. Rolling resistance e.g. the friction between wheel flanges and rail is an energy loss and needs to be minimised across both the towed and towing components.
Many railway vehicles do have tyres. The wheel is a solid block and the tyre is a shaped ring which is heat expanded allowing it to slip onto the cold wheel and when it shrinks grips the wheel firmly. A steel rings then is clipped into place to secure the tyre. This allows the tyre to be scrapped when it reaches its wear limit. More recently there has been a move to monoblock railway wheels where the tyre and wheel are a single piece of steel and when the wear limit is reached the whole wheel is scrapped.
@@JohnAshworth2023 I've worked across alot of fleets in the UK, analysing wear patterns, gauging, changing wheelsets and operating wheel lathes and yes modern diesel and electrics do have tyres, Trams too. Most people outside the Railway assume the word 'tyre' means something made of rubber.
If Grady ever wanted to lure me in to kidnap me for some reason, all he'd have to say is "Come take a look at these demonstrations in my garage" and I'd follow without a second thought
The German high speed rail trains ICE (inter city express) actually started out with rubberized steel wheels to reduce vibrations and thus increase passenger comfort. That stopped when we had a horrible accident at Eschede. What happened was that the rubber sleeve of one wheel started tearing off roughly a few kilometers before a switch and a piece of rubber jammed itself into the switch, forcibly changing the tracks for the rear part of the train. This derailed the entire train that had been going around 200 km/h (~125 mph), which would have been bad enough, but only led to broken bones in most cases. The problem was that a few hundred meters after the switch came an overpass and the sliding train took out the pillars of the bridge, causing the bridge with cars on it to collapse onto the train. All in all, more than 100 people died.
Correction: The rubber was just one layer in between the steel hub and a steel outer ring that ran on the rail. The rubber was indeed there to reduce vibration, but it also allowed the outer ring to flex under the weight. This caused fatigue in the outer ring until one finally broke. The steel outer ring is what lodged itself into the carriage and caused the derailment.
@@keithstudly6071 Original comment described "a piece of rubber jammed itself into the switch", which is based on a misunderstanding. I specified "steel outer ring" to avoid confusion about the materials involved
Thanks, Brady. I live right next to the Main Line of the Pennsylvania Railroad, now the Amtrak line between Philadelphia and Pittsburgh. The line is used by Chesapeake and Ohio and by Philadelphia commuter trains of South East Pennsylvania Transportation Authority (SEPTA). I've learned to recognize the wheel to rail sounds of each.
I used to have a balcony over that line! Stayed up one night watching them replace ties, had never seen anything like it, or had much interest in trains, before seeing 20 something maintenance cars come through for that.
The Nebula subscription is definitely worth it! The extra content and ad-free experience make it a great platform to support creators while enjoying high-quality videos. Thanks for the recommendation, Grady!
I signed up but ended up using UA-cam anyway because it has more features like comments, which makes it a better experience for me even with ads, if they could add those things it would be helpful but then you'd have two separate comment sections
6:00 The problem here is that you are measuring the sliding coefficient of friction, and railroad wheels as well as car tires do not slide, they roll. The friction is static which is a higher value. Theat is the reason cars now have automatic systems to prevent skids. Once a tire slides (skids) the friction drops dramatically. The way you measure static friction is to place your sled on a plane and tilt it until the sled breaks loose and begins to slide. The coefficient of static friction is the tangent of the angle, or more simply the height of the end of the board divided by the horizontal distance from end to end, or as we call it rise divide by run. I've had my Physics student do this hundreds, if not thousands of times over the 33 years I taught Physics.
The ad for Nebula at the end was so good. No this isn’t sarcasm. I’ve heard about Nebula since a few years ago, but your way of presenting the platform, and how it compares to other platforms (loved the How it’s made reference) was just so watchable. You might’ve actually convinced me to give it a go, so hats off to you sure for producing such great content!
Several decades ago I was lucky to go on a ride a long in the cab of a diesel electric through the Appalachian mountains on a short line. It started raining lightly as we were going up a mountain and the wheels were slipping. The sander was not functioning. They had me stand at the front of the locomotive sprinkling sand on the track in front of the train so we could ascend. Such a cool experience.
Excellent lab tools, sir. Have been studying railroad systems, both domestic and international (I lived for two years next to a Japanese rail freight track) for over 60 years as a hobby, and your ongoing series is comprehensive and much appreciated. One point of expansion, steam locomotives do slip more, due primarily to their reciprocating tractive effort, and the uneven rotational wheel force. Steam has much better ' to the wheels' tractive effort, but getting it to the rail is to the Diesel's advantage, and your point of MU operation distributing that force was explained beautifully. Thank You Sir!!
That's one of the biggest things between steam and diesel. Diesel can start a train off better but a steam loco is better for speeds in it's designed speed range, 70-100km/h for a lot of them. That's where steam is actually more efficient than diesel if a modern design of steam loco is used.
As soon as I saw the title I was thinking..."But many locomotive Do have tyres though" Especially Steam Locomotives! I don't know of a single design that doesn't. Back then, they were well aware of the lack of friction between the driving wheels and the rails, So these hard wearing "tyres" were installed to help increase the friction without affecting the rolling resistance too much. Also alot of steam locomotives were very prone to wheelslip. Some were better than others, but generally, the larger the wheel the more likely it was to slip. Hence why alot of freight locos had relatively small driving wheels. So the reason for tyres on Steam engines was purely cost saving. The Driving wheels are very expensive to mold and machine (Some can be in excess of 6 or 7 foot in diameter), So they put tyres on, these ware out and you just put on a new set. Saving the steel part of the wheel and a truck load of money in the process.
It's kind of an issue with terminology across cultures; the US population (example; me) generally only refers to something as a "Tire" if it's the removable rubber kind.
Diesel locos had tyres too. I know this because I have shares in ownership of class 20, 31 & 47 BR diesel locos and back when I was a active volunteer we painted white marks across the sides of the tyres and onto the wheel hubs so that it was easy to spot if a tyre had slipped.
@@matthewutech5970 Wheelwrights use the term for wooden cart wheels which have been around since forever. A shrink fit steel tire/tyre that holds the wooden wheel together.
Actually the other half is to clean the tires. Tires are soft and you don't want the small stones and powdered concrete picked up by driving from the pits (or return road etc) to be dropped along the track, That could potentially lead to a car traveling at high speed to come unstuck and hit the wall or opponent. -You go through the water to get the tires slightly wet which helps lower traction to help all cars start the burnout. -You don't do the burnout in the water which would spray everyone, you roll just ahead of it. -During the burnout any small stones previously picked up from the pits are flung off and out leaving the tire cleaner and obviously allot warmer. -When done on a street race sometimes water will be used and other times a VeryHighTraction fluid is used by pouring ahead of the wheels and the car moved into it. -As the burnout is done the whole wheel gets coated, VHT is already sticky but it can also help break down the rubber and make it even softer and give yet more grip, As the car moves forward this helps transfer some of the rubber from the tire onto the street for a rubber-rubber contact.
Very interesting. Steam locomotives have steel tires on their wheels. When they wear down, they are replaced, just like a car tire. Diesel locomotives have witness grooves in their wheels, which determine when the wheel has to be replaced. The factor of adhesion was always a consideration with steam engines. Too low of a factor and the engine would be limited in its use. Diesel and steam engines are inverse in how they put down power and all of this starts with the factor of cohesion. This is another subject, really, but it is all part of the whole.
Steel tyres can work on slow steam trains and trams but the engineering community has moved away from steel tyres after the Eschede high speed train crash in Germany. When one of the tyres cracked then got caught on some points. The tyre unrolled itself into a spear that penetrated the carriage. Over 100 dead. Anyway steel tyres are more trouble than they are worth with machining, press fitting and the danger of them coming apart. Much easier/safer to make a solid wheel, when they wear recycle them to make new wheels. Its amazing that train technology hasnt changed much in 300 years when it comes to wheels and rails. Other than minor improvements like welded rail its basically the same.
@@tubester4567 Yes, I know of this accident. It was caused by the tire separating from the rubber damping ring, between the tire and the wheel. They used this design because of vibrations caused by the original steel wheels, at high speed. They thought that this would mitigate the problem. This design was never meant for high-speed applications. It was never tested for this type of use. Steam locomotive tires were pressed on hot and allowed to cool, shrinking them onto the wheel. This made them an integral part of the wheel This is how they did it in the age of steam. Rubber dampers were never part of the equation on steam locomotives.
@@tubester4567 Yes, I know of this accident. It was caused by the tire separating from the rubber damping ring, between the tire and the wheel. They used this design because of vibrations caused by the original steel wheels, at high speed. They thought that this would mitigate the problem. This design was never meant for high-speed applications. It was never tested for this type of use. Steam locomotive tires were pressed on hot and allowed to cool, shrinking them onto the wheel. This made them an integral part of the wheel This is how they did it in the age of steam. Rubber dampers were never part of the equation on steam locomotives.
@@alistairwhite2906 Only on trams and slow speed/historic trains. Many modern trains are even moving the brakes from the wheel to a separate brake disc rotor. Most of the wear on train wheels comes from the brakes.
In the UK (And probably elsewhere, idk) trains actually do have tyres, they're just also made of steel, because it's cheaper and easier to replace the detachable band of metal round the edge of the wheel than the entire wheel. Edit: Ok, I spelled it wrong, I get it.
Correct. They all have tyres (correct spelling in English), it’s just not vulcanised rubber. Changing a steel alloy tyre is cheaper than scrapping a wheel.
Trains also get "flat" tyres/tires at times This is usually from brake problems or harsh (emergency?) braking where a wheel skids along the rails for a distance without turning.
Only tyres on older locomotives , even on the 1970's class 56 we started to fit Monoblock wheels , waggons virtually all have Monoblock wheels . We did get problems with tyres if they had been heated due to dragging brakes , the tyres would move on the wheel this is why you often see white pain marks on wheels ,tyres had secondary security the gibson ring on inside of tyre
When I was a kid, I worked at an amusement park and drove the train around the park. Periodically, the rails on the turns would get greased and sometimes too much grease was applied or it would rain and the grease would get really slick and I would have to get out and sand the rails on an uphill slope.
Nice work in explaining creep! I always find it difficult to explain it to others without involving differential equations and material flow. I never thought about bristles on a rotating disc! That was amazing! Also a small nitpick is the stick slip illustration. The leading edge is always in stick. Only the trailing edge slips within the contact patch. As the creepage increases the slip area completely covers the contact patch as you showed.
11:37 You can see the Helmholtz waves in the vibrating violin strings. Strings that are being drawn by a bow don't oscillate like a sinusoid as you'd expect. Instead they vibrate as a triangle wave with a moving apex called Helmholtz waves.
You mentioned cold welding and how you weren't going to get into it. But honestly, even though I've seen a few UA-camrs mash two pieces of extra-smooth metal together and - seemingly by magic - get them to stick together, I never considered the practical, engineering implications of this phenomenon. I think it would make a great video to talk about this, if only briefly.
Yeah, I think that's why he started with "it's the weight" and then generalized to "it's actually the normal force which includes other things." For the purpose of this video, I think "weight" is good enough. Trains don't usually pull a lot of G's around corners, and I venture that aerodynamic effects aren't a big component. (Though somewhere there's a good ol' boy with a spoiler on his loco...there has to be. 😂)
Point of order: they do have tyres, it’s the outer steel of the wheel. They can be ground to restore the desired profile or rotated around the locomotive during maintenance. They can even be replaced during midlife overhaul 😃
Spent 4 years working on a metro project overseas. As an Interface Manager, now retired, between the three consortiums I had the privilege to read various train to rail test reports. At the time, and due to my background as an electrical engineer, I learned many things but not to a great depth. This video enabled me to connect several dots and several of those reports now make complete sense. Thanks for sharing.
i always wondered why locomotives experienced wheelslip if they applied full engine power when starting to move. now i know it happens from the contact patch getting less traction because the train is forcing its full tractive effort at a low speed... even as a long-time railfan im still learning new things and it really brightens my day, grady
I always like watching your videos on rail topics. The sister company of the company I work for specializes in modernizing locomotives and rail cars to make use of newer technology to improve fuel economy, emissions, maintenance costs and fleet management of rail operators. It is nice to see other people talk about the engineering in the rail industry.
3:28 Friction isn't a horizontal line, it's actually sloping down as approximated by the Curtius-Kniffler formula. At higher speeds you don't have the same adhesion as you have at standstill.
0:00 I think that's Indycar and some sort of junior open wheeler championship, not formula 1 Edit: Hey, since you're working on subject of train. Why don't you do a collab with Hyce? He's on UA-cam and his day job is an operator/engineer/fireman of a steam engine and part time mechanic/fabricator at Colorado Railway Museum
I ride dirt bikes, and you mentioning F1 and tire traction made me think about Stark Varg the new electric dirt bike. A lot of people say it will be unfair because of the instant power and torque it can create, but as you said it's about the traction. You can have a dirt bike that makes 1,000 hp but if you can't get the power to other ground then it doesn't matter.
we all know you’re from the USA, but maybe you could open with „here in the USA, most locomotives have a diesel electric drive train“ 😂 In Europe diesel is not common, but this is just a small little thing 😊 great video! enjoyed watching it, including the definitely-F1-Cars 😂😊
Great explanation of how wheel creep works. My dad was one of the engineers who worked on the implementation of EMD's Super Series wheel slip/creep system. The EMD 50 series locomotives used a radar system to measure the actual ground speed of the locomotive. I know my dad worked on the radar system design and the high voltage cabinet (where the 50 series control system modules live).
Some French trains are now sitting sad in a corner sipping there wine out of the bottle. wile looking at its rubber tires. Thinking Am I not a locomotive?
@@cr10001it sure is. There is one carriage that is also the locomotive. As it houses the bulk of the engine if not all of it. Making it a locomotive with rubber tires.
Not only replaceable ‘tyres’ but they come in different ‘compounds’! In Wellington, New Zealand, the new passenger units were found to be wearing the rail at an unacceptable rate. This was due to the bogie design making them longitudinally stiff. The leading bogie wheel was biting to hard into the outside rail in curves. The tyres having a ‘hard’ compound were grinding the rail. Solution. Softer compound. More tyre wear, less track wear. The down side to this was the tyres were more susceptible to slip/slide and thus often ended up with flats. The extra lathe time and shorter overall life was an unfortunate side effect. Great post Grady. 👍❤️
"... I have a couple of demonstrations set up in my garage..." Well, that *is* why I'm here. 🙂 Seriously, your practical demonstrations make these concepts *so* much clearer. Thanks for going to all that trouble!
As a locomotive tech, I remember reading in a manual somewhere about wheel creep. If I remember right it said that adhesion increases significantly when wheels are allowed to creep at about 1-2 mph above track speed. This was a neat demonstration of why that happenes. Neat.
We were told 7% slip/creep was the ideal amount , first loco's we had with wheel creep where the UK class 60 , this system required radar to measure speed and wheel speed sensors in traction motors . GM class 66 has a crude version of this with radar but no individual wheel speed sensing "super series " nowhere near as effective as the older UK built class 60 wheel creep
@nounoufriend1442 I do believe more modern locomotives have a system with radar and TM speed probes to measure the amount of slip. That being said, where I work we only have ancient power. The newest stuff we have are SD40-2s so I won't claim to be super familiar with anything newer than that.
Even on youtube, paid channel subscriptions make a lot more money per viewer than any amount of ad revenue. As a platform very open about not looking to pursue profits at the expense of UX and quality, they'd be foolish to ever include ads on their website.
Trains are amazing. I used to take my daughter to the train crossing on oir bikes so she could feel the earth shake. She still respects the trains... And is slightly afraid of them
Some rail vehicles have tires, for example trams have a rubber ring in the steel wheel. On June 3, 1998, an express train equipped with wheel tires had an accident in Germany. Wikipedia Eschede train disaster The rubber ring in the wheel had caused cracks in the steel tire, high speed, a broken crack, a switch and then a pillar of a bridge led to the catastrophe. The front locomotive and the first car still passed under the damaged bridge. But all the other wagons and the rear locomotive collide with the collapsing bridge. Afterwards, this technology was removed from express trains. The train line was initially shut down and later modified.
On October 19, 1875, a steam locomotive derailed in the Timelkam railway accident in Austria due to a broken steel wheel tire. Since the coupling broke off, the rest of the train remained on the rails. There was only material damage. The reason was probably that the connections between material strength and brittleness had not been researched.
@@Derkiboi Engineers try new concepts. This sometimes goes wrong. In the Enschede case, wrong decisions were made by many responsible people. And then all the bad luck came together. The court could not find the one culprit, but spoke of the failure of many. Ultimately, everything boiled down to monetary payments to those who were in the accident.
The contact patch size reminds me of two similar things that blew my mind when I learned about them. The first is that steel power poles are held up only by the 4-20 bolts through them and not the large flange that more often way off the base. The second is that all of the force holding your car up on the wheels is concentrated on 2 tiny roller bearings at a time per wheel. Not sure that the total contact area is but it's itty bitty for sure
I actually experienced that first demonstration you made at my local gym. They're renovating and they replaced the Astroturf for the sled. Gosh is that thing HARD to push now! Before on the matted-down turf, I was pushing ~235lbs or 106.594kgs, now I can barely push 135lbs or 61.235kgs on it! Friction changed EVERYTHING and it is seriously underestimated.
Locomotives have steel, rather than rubber, tires because steel is much more elastic than inflated rubber. This means the losses to heat from compression and rebound are much less from the flexing of the steel than they would be from rubber undergoing the same stresses.
Finally, someone else who knows train wheels have tyres. Granted most railways are moving to solid wheel systems, but wheel and tyre still exist. Just as rubber tyres come in different compounds, steel wheels are no different. ‘Hard’ tyres last longer but are hard on the outer rail on curves. ‘Soft’ tyres are more gentle on curves but easily get flats if the get into slides. The balance between the cost of maintaining the track verses more regular re-turning the tyres.
Not gonna lie, Grady. this one was over my head. I’ve never taken a physics course in all my years of education and you can usually explain concepts of physics as they relate to the engineering in question so that I get them right away. I’m gonna have to watch this one a few more times. It ended and I was like, “oh…he didn’t explain it yet…”. I’ll get there
Steel is such an amazing material. Just on its face, it's amazingly versatile, but when you think of rails that trains drive on, it's really mind-boggling what it can do.
A lot of people yes, but what about children or those who haven't come across this before. There are also a lot of places in the world with poor education.
Most freights are designed to start with a progressive yank instead of a straight pull. If the full length of the train was parked with all of the 'slop' in the couplers pulled tight, the engine would not be able to start without stalling or slipping traction. You can hear this effect when the long trains stop and start.
When I was very young we lived near railway tracks. At that spot we were near the top of a notable incline. I well remember the struggles of locomotives to pull their loads, particularly as they were nearly all steam driven in those days. In rainy weather they often didn't make it, and the loco's wheels would spin up in a frenzy of rapid and loud huffing and puffing
Another thing to mention about the steel on steel design is that more flexible materials like tires physically squish under weight, and all the energy that goes into squishing the tire is energy not converted into forward motion. This is one of the reasons why semi trucks are so unbelievably inefficient when compared to cargo rail for moving the same weight.
0:44 This is not exactly the subject of the video ,but the adherence force applied by the road to the car is directed toward the inside of the curve. This produces the acceleration that curves the trajectory of the car. Very interesting video !
Absolutely brilliant video. You can see the improvement over time in your ability to summarise fairly complex engineering concepts and present them in an accessible and engaging way.
Well as you mentioned trains can also have steel tires: They are cheaper to replace because you basically only put in a thic strip of metal, BUT you will find such wheels only on really old locomotives that still have spokes and now you might ask yourself why we bon´t use this type of wheel anymore. The answere is: Braking, yes braking. Old locos and wagons (at least in austria they would be old) use brake pads to create friction to slow down the rotation of the wheel to slow down the train and we all should know that friction creates heat and that warm metal expands so in some cases, when a train went down a long hill these tires got hot, expanded and fell of which caused the train to derail. And that´s why Austria and many other countries use disc brakes and tireless wheels... (If there are some mistakes in this coment, don´t hate me I´m austrian🙂)
Some time I'd love to hear you discuss highway pickups modified for rail service, which use steel wheels to bear most of the weight but tires for starting and stopping.
That graph of decreasing friction the faster you go made me realize how complex high-speed trains are. Imagine the power needed to continue gaining speed at such intense rotations of the wheel
Hello Grady. I just bought a copy of your “Engineering in Plain Sight” book. It really caught my attention at Barnes & Noble. And now I read about this UA-cam channel. I’m looking forward to reading your book and watching your channel! 👍
I wish your garage demonstrations had discussed the (significant) difference between the coefficients of static and dynamic friction. You generally don’t want your wheel contact patch to be sliding across the traction surface - this is hard for non-engineers to realize, but the contact area of the wheels of your car - or a train - are stationary relative to the surface. So the coefficient of static friction is what generally governs overall traction power.
I think he explained the difference between static and dynamic friction very well. It wasn't obvious to me in the garage model, but I know from experience that it's harder to get something moving (like a chair) than it is to keep it moving when you drag it. And his graph showed the implications of this at railroad scale.
The difference between static and kinetic friction is such a vital lesson in physics. For the inverse reason, a cars ABS does the same thing as the train; Keeping the wheel at peak grip without slipping, in order to slow down the car as fast as possible.
that f1 analogy of soft tires for speed and hard tires for durability is incredible! take it to the extreme and viola, hardened steel tires on hardened steel rails
Look at the video called "NS 13T Epic struggle uphill" to see wheel slip correction working its absolute hardest. Creep control is only used once the speed begins to climb above 5 MPH because of how ground speed is measured if my memory serves me right. That has a very constant squeal from the wheels being allowed to slip a bit.
"Formula 1 cars..." (Immediately shows indycar and f4 cars) Love your content and this video, that just made me chuckle a bit lol. I see your pinned comment and fully understand how F1 is about licensing!
The UP BigBoy series were that one giant locomotive used to move a large train. It was able to move trains up steep grades that previously required doubled engines
Some trains DO have tyres! The derailment at Eschanade in Germany was caused by an ICE (inter city express) train fitting with dual block wheels, meaning they had a layer of rubber followed by a second layer of steel over the wheel. This provided some cushioning to the wheels, minimising sound and vibration before the invention of continuously welded rail. However, poor/nonexistent maintenence led to the outer layer of steel coming loose and getting stuck in the train body, and forcing a derailment when it encountered a junction.
That was an unusual design. The majority of wheels (that aren't monoblock) have steel tyres shrunk direct onto the steel wheels. This was universal for steam locos, and probably a majority of diesel/electric locos in Europe. The derailment was at Eschede, by the way.
You should look into drag racing cars that use that slip curve to their advantage as well. Especially in the lower speeds as they launch. It’s fascinating engineering used there as well.
Sorry for the lack of actual F1 cars in the intro! Turns out, very hard to license footage 😄
The finale for the railroad series is now on Nebula! nebula.tv/videos/practicalconstruction-installing-a-water-main-below-railroad-tracks?ref=practical-engineering
Starting with "Formula One is..." while showing Indycar is a really good way to get a lot of people up in arms. 😄
@@panchordid you just copy the top comment?
Doing anything with Formula 1 is a recipe for either getting hosed for way too much money, or for having their commercial rights holder come after you with bogus charges of copyright infringement. Ask me how I know 😅
Well, at least you know they're not F1 cars 😂
Before I watch the rest of this video, I hope you address the important and often overlooked fact that trains don’t have steering wheels. OK, let’s roll the video.
I was a location manager and had a retired train engineer working for me. When I was having a "challenging" day, Brad would see this and say, "David - How do you start a train?" and walk off. One day, I stopped him and asked him what he meant by that statement.
"There is no locomotive set that can possibly pull a mile long train from a stand still. The locomotive pulls the first car, which pulls the next car, which pulls the next." The slack in the coupling is crucial to allow this 'chain reaction' to occur.
He shared that sometimes, with a green engineer, they'd pull into a stop to change crew while under power, taking all of the slack out of the couplers. No go. The solution was to back the train a distance to re-create the coupler slack.
So, the life lesson was, if you have a big challenge you're dealing with, find the solution in a series of small fixes rather than viewing it as one big problem ... one car at a time.
Well said.
Thanks for posting this.
Oh. I thought the lesson was, "Back up and get a running start." 😅
Hmm.. "How do you start a mile-long train from a stand still? You take the 'R' out of 'rail' and the 'F' out of 'way'."
"There is no 'F' in 'way'."
"Exactly."
I think you've misunderstood what was said, you don't back a train up to increase slack before starting, and indeed taking any single bit of rolling stock from 1kph to 2kph takes more energy than taking it from 0kph to 1kph.. common practice on the rail line is to creep forwards in low throttle notches till the rear of the train starts to move, and only then add most of the power, otherwise your being very rough on the rear couplers with all that inertial jerk (there are springs in all couplers but the locomotive to help reduce it, and this will actually cause a stopped train braked only at one end to "equalize" very slowly on low grade track), and on bigger trains will break them outright. But "how do you start a train" is still the correct saying, because it starts slow, you don't feel like your doing much and if you kept going at this rate you'd never make it in time.. but you keep going and as you keep working on the problem you get the means to apply more force and solve the problem faster.
One car at a time...Beautiful
Grady is just so wholesome. Listening to him talking about engineering is like receiving a big informative hug.
BUZZWORD ALERT. MASSIVE CRINGE. NPC.
Information hugs are the best
I like him because he’s balder.
Great expression!
"A big informative hug" just about sums this channel up lol
I work for Wabtec (former GE Transportation), we build freight locomotives. The sheer weight and power is unbelievable.. they are truly an engineering marvel.
Spend some more time on making sure the rear cab door seals correctly. Thanks
Nah wabtec would likely drop support for legacy loco platform like C20EMP or slightly new CM20EMP. I hear some parts difficulty for these type. They would pushing GEVO to everywhere
Here's a good way of putting it into perspective for people: Most people see UP's Big Boy as some kind of measuring stick for locomotive pulling power, but it's effectively 2 large steam locomotives permanently connected to form a single huge steam locomotive, and still has about 30,000lb less continuous pulling capacity than a single ES44AC.
Tell Wabtec to stop BULLYING its way into California's trains. Taxpayers in California should use the OPTIMAL system for signaling. NOT just Wabtec because Wabtec is American. You can't preach FREE MARKET ANARCHY i.e. CAPITALISM when it benefits you, but then push ANTIFREEDOM BIG GOVERNMENT NATIONALISM PROTECTIONISM when FREEDOM to choose superior European designs is not in your favor.
@@ErickC that may be true, however diesel electric engines are by far more efficient. Especially with maintenance costs and environmental impacts.
starting with "Formula One is..." while showing Indycar is a really good way to get a lot of people up in arms. 😄
But clearly not as many people who seem to read this comment as some sort of insult, indictment or judgement. Ya'll must be fun at parties.
Lighten up 🙄
No such thing as bad engagement metrics. All hail The Algorithm!
I think its a F2/F3 car
I'm guessing it has to do with copyright
@@Tobyphoto69 the second batch of cars appear to be F3 or some other junior formula. But the first shots are Indycar circa 2012-14.
@@de-fault_de-fault missed that part
Excellent video, Grady! The "Creep" demonstration was wonderful. This effect actually leads to one of the biggest wheel defects we experience in the railroad - shelling. The creep and deformation actually causes slip dislocation motion in the grain structure of the steel, and atoms start getting peeled out of the wheel, and thrown off - resulting in shelling, which is essentially a "missing chunk" of wheel.
Also, Steam Locomotives actually *do* have tires! Different hardnesses as well, depending on the size and weight of the locomotive. They're really neat. The wheel on a diesel locomotive is a much simpler, and standardized part that can just be replaced; so the whole wheel just gets changed out; but with a steam locomotive and their various wheel sizes, castings, etc. - it made sense to have a dedicated tire to replace, instead of a complicated casting.
Hyce watches this?!
Hey guys this is Ice.
@@teeboy4158 Technology conextras also watches this, and both grady and Technology Connextrass channels have mentioned (phrases) of one another.
My grandfather was a machinist changing treads on steam wheels. Not just slip, but out of round because of connecting rod. I thought new wheels had hardened 'treads' that could be resurfaced on a lathe if not too worn.
spalling?
I'm sure Brady knew the cars at the beginning were not Formula 1 cars, because F1 is very protective of copyright, and he didn't want to deal with the headaches.
Yes, very true, that is exactly what I thought.
So he should have changed the wording to not suggest those were F1 cars.
@@kngofbngbut he was talking about something relating to F1 cars. I don’t see the problem, he just needed a visual aid, and he got one. He could’ve drawn a F1 car on a whiteboard and it would’ve done just as well.
But they are the same type of cars, so it gets the point of it bieng a race car
I mean he could use an ai generated image or video of f1 to gray area out of copyright if he really wanted an f1 car 🤷♂️ but i agree, saying "race car" would have been a better choice.
0:04 It's also the pinnacle of Copyright Strikes. Therefore, have some Indy Cars instead.
That's not footage of F1
@@CableWrestlerthats why they literally said indy cars and not f1 in their comment
Are you slow @@CableWrestler
i swear about 9/10 videos you make could just be called
"check out this cool thing i built in my garage"
and i'm here for it.
Was a tanker in the Army and this principal reminds me of how tank track moves. You'd think that the tank track, rotating but laid down stationary, under the tank wouldn't move until the rear end of it gets lifted and starts moving up then forward only to get laid down again, in a cycle. The fact is, when a tank is really hustling, all 60+ tons, the track thats in contact with the ground, which may appear not to be moving, is in fact sliding forward with the tank, slightly but evidently. If you watch closely and see video of a tank moving quickly, especially over a hard surface like pavement, you'll notice that the track on the ground is sliding, "creeping", forward as the tank moves. Pretty cool physics going on there too.
Oh. Thanks. That helps me understand a lot better! 😊
Hard to imagine a solid steel wheel stretching and effectively increasing the size of its contact patch to obtain maximum tractive effort. Its actually genius. Once the tractive effort reduces, the contact patch shrinks to its normal size and rolling resistance becomes minimal at cruise. The more I learn about trains, the more respect I have and the cooler I think they are.
The physics is basically the same with automotive tires, just with rubber and air not solid steel.
Isn't it the exact opposite? Contact patch has two parts, one under static friction (stick), and one under dynamic (slip). Stick area has higher coefficient of friction, slip has lower. Each carries its own portion of the train's weight. But when we try to increase torque to get more tractive effort, stick area decreases, so slip area carries more weight - so shouldn't the effective friction coefficient only go down?
I don't think it's the _size_ of the contact patch that provides the extra friction, it's the _shape,_ which alters the effective coefficient of friction. As friction is weight × coefficient, notice how there's no contact area term in that equation at all. All else being equal, _the area doesn't matter._ Think of it this way: with bigger contact patches, the friction is spread out over a larger area - but this is _exactly balanced out_ by the fact that the (gravitational) force pressing the contacts together _is also spread out_ over the same larger area.
Of course, in the real world, all else is not equal. A certain size and number of wheels or tires _can_ be helpful. But it's not _directly_ from the size of the contact area. I think the reasons are:
- Greater contact area, lower pressure. (Pressure, e.g., pounds per square inch, is weight divided by area. So, for example, a 3000-lb vehicle with 30-psi tires will have a total contact area of at least 3000 lb/(30 lb/in²) = 100 in². If contact area is smaller than that, tire pressure will need to be higher.) And at lower pressure, rubber tires deform, increasing their coefficients of friction. (The deformation of the train wheels is the thing you're talking about as well.)
- A large contact area is good for averaging out the variable friction of a real-world surface (e.g., ice, oil, gravel, painted lane stripes).
- (Not related to friction, but) a lower pressure also means the wheel and the road don't have to be engineered for a higher pressure.
4:10 Rolling friction (or rather, rolling resistance) isn't the same as adhesive friction. Adhesive friction is GOOD for rolling, it's what defines it. Rolling resistance is bad, unless you want to brake.
This is the distinction people often forget to point out, which usually leads to confusion. Weaker adhesion doesn't help you roll better.
Excellent point - underrated comment.
Engine wheels have torque applied to get them moving.
Rolling stock* wheels should have minimum turning resistance
* there is a clue in the name.
Rolling resistance e.g. the friction between wheel flanges and rail is an energy loss and needs to be minimised across both the towed and towing components.
You guys are dorks
@@scav3155don't you have anything better to do with your life?
@@scav3155and proud of it
@@flallana18 I'm actually a dork myself lol
Me: About to eat lunch, UA-cam: Hey Practical Engineering just published a new video about trains. Perfect timing. 👍
Same! 😇
Me when either of you upload during lunch haha
why tell the world?
Bon appetit
same here
Many railway vehicles do have tyres. The wheel is a solid block and the tyre is a shaped ring which is heat expanded allowing it to slip onto the cold wheel and when it shrinks grips the wheel firmly. A steel rings then is clipped into place to secure the tyre. This allows the tyre to be scrapped when it reaches its wear limit.
More recently there has been a move to monoblock railway wheels where the tyre and wheel are a single piece of steel and when the wear limit is reached the whole wheel is scrapped.
Yes I have seen the steel tyres replaced on steam locos.
Agreed. Steam locomotives definitley have metal tyres. I don't know about modern diesel and electric locomotives.
@@JohnAshworth2023 I've worked across alot of fleets in the UK, analysing wear patterns, gauging, changing wheelsets and operating wheel lathes and yes modern diesel and electrics do have tyres, Trams too. Most people outside the Railway assume the word 'tyre' means something made of rubber.
If Grady ever wanted to lure me in to kidnap me for some reason, all he'd have to say is "Come take a look at these demonstrations in my garage" and I'd follow without a second thought
Demo...napping
Hey kid, I've got simplified science experiments in my van wanna see?
And he gets away with it in the end because there was no abduction or threats, just several weeks of playing with cool engineering in his garage.
@@WyvernYT I was in Grady garage for a full week before I figured out I had been locked in.
@@ddegn I was too busy playing with the toy construction equipment in the sand table to realize he locked the door
The German high speed rail trains ICE (inter city express) actually started out with rubberized steel wheels to reduce vibrations and thus increase passenger comfort. That stopped when we had a horrible accident at Eschede. What happened was that the rubber sleeve of one wheel started tearing off roughly a few kilometers before a switch and a piece of rubber jammed itself into the switch, forcibly changing the tracks for the rear part of the train. This derailed the entire train that had been going around 200 km/h (~125 mph), which would have been bad enough, but only led to broken bones in most cases. The problem was that a few hundred meters after the switch came an overpass and the sliding train took out the pillars of the bridge, causing the bridge with cars on it to collapse onto the train. All in all, more than 100 people died.
Correction: The rubber was just one layer in between the steel hub and a steel outer ring that ran on the rail. The rubber was indeed there to reduce vibration, but it also allowed the outer ring to flex under the weight. This caused fatigue in the outer ring until one finally broke. The steel outer ring is what lodged itself into the carriage and caused the derailment.
"Outer Wheel" is the tire! Not all tires are rubber! @@namewarvergeben
@@keithstudly6071 Original comment described "a piece of rubber jammed itself into the switch", which is based on a misunderstanding. I specified "steel outer ring" to avoid confusion about the materials involved
6:51 "For longer, heavier trains, you can't just use a single, massive locomotive -"
Union Pacific during the transition era: "Wanna bet?"
yep... this seemed like a good opportunity to include a clip of the recently restored Union Pacific steam locomotive Big Boy #4014. Very impressive!
The Big Boy is basically two locomotives in one, albeit with a single cab and firebox
while true, the challengers and big boys were articulated, and had a lot of wheels, so the weight limits weren't reached
Gas turbine locomotive: Hello there
It's a shame he didn't include something about the Big boy and the Challenger locomotives. They put the diesels to shame in power.
A sophisticated creep control system. I would have often needed that in my life. 🤔
Thanks, Brady. I live right next to the Main Line of the Pennsylvania Railroad, now the Amtrak line between Philadelphia and Pittsburgh. The line is used by Chesapeake and Ohio and by Philadelphia commuter trains of South East Pennsylvania Transportation Authority (SEPTA). I've learned to recognize the wheel to rail sounds of each.
I used to have a balcony over that line! Stayed up one night watching them replace ties, had never seen anything like it, or had much interest in trains, before seeing 20 something maintenance cars come through for that.
By "Chesapeake and Ohio" do you actually mean CSX? I think that CSX's "bright future" paint scheme is a throwback to the Chessie.
The Nebula subscription is definitely worth it! The extra content and ad-free experience make it a great platform to support creators while enjoying high-quality videos. Thanks for the recommendation, Grady!
I signed up but ended up using UA-cam anyway because it has more features like comments, which makes it a better experience for me even with ads, if they could add those things it would be helpful but then you'd have two separate comment sections
6:00 The problem here is that you are measuring the sliding coefficient of friction, and railroad wheels as well as car tires do not slide, they roll. The friction is static which is a higher value. Theat is the reason cars now have automatic systems to prevent skids. Once a tire slides (skids) the friction drops dramatically. The way you measure static friction is to place your sled on a plane and tilt it until the sled breaks loose and begins to slide. The coefficient of static friction is the tangent of the angle, or more simply the height of the end of the board divided by the horizontal distance from end to end, or as we call it rise divide by run. I've had my Physics student do this hundreds, if not thousands of times over the 33 years I taught Physics.
The ad for Nebula at the end was so good. No this isn’t sarcasm. I’ve heard about Nebula since a few years ago, but your way of presenting the platform, and how it compares to other platforms (loved the How it’s made reference) was just so watchable.
You might’ve actually convinced me to give it a go, so hats off to you sure for producing such great content!
Several decades ago I was lucky to go on a ride a long in the cab of a diesel electric through the Appalachian mountains on a short line. It started raining lightly as we were going up a mountain and the wheels were slipping. The sander was not functioning. They had me stand at the front of the locomotive sprinkling sand on the track in front of the train so we could ascend. Such a cool experience.
That brush-on-rug demonstration of creep was amazingly intuitive and clear.
"I've set up a demonstration in my garage."
Of _course_ you did. That's what we love about you, Grady.
Excellent lab tools, sir. Have been studying railroad systems, both domestic and international (I lived for two years next to a Japanese rail freight track) for over 60 years as a hobby, and your ongoing series is comprehensive and much appreciated. One point of expansion, steam locomotives do slip more, due primarily to their reciprocating tractive effort, and the uneven rotational wheel force. Steam has much better ' to the wheels' tractive effort, but getting it to the rail is to the Diesel's advantage, and your point of MU operation distributing that force was explained beautifully. Thank You Sir!!
That's one of the biggest things between steam and diesel. Diesel can start a train off better but a steam loco is better for speeds in it's designed speed range, 70-100km/h for a lot of them. That's where steam is actually more efficient than diesel if a modern design of steam loco is used.
As soon as I saw the title I was thinking..."But many locomotive Do have tyres though"
Especially Steam Locomotives! I don't know of a single design that doesn't.
Back then, they were well aware of the lack of friction between the driving wheels and the rails, So these hard wearing "tyres" were installed to help increase the friction without affecting the rolling resistance too much. Also alot of steam locomotives were very prone to wheelslip. Some were better than others, but generally, the larger the wheel the more likely it was to slip. Hence why alot of freight locos had relatively small driving wheels.
So the reason for tyres on Steam engines was purely cost saving. The Driving wheels are very expensive to mold and machine (Some can be in excess of 6 or 7 foot in diameter), So they put tyres on, these ware out and you just put on a new set. Saving the steel part of the wheel and a truck load of money in the process.
The "tires" used in this case are also metal and if I remember correctly some modern trains use the same tech because cost savings.
It's kind of an issue with terminology across cultures; the US population (example; me) generally only refers to something as a "Tire" if it's the removable rubber kind.
Diesel locos had tyres too. I know this because I have shares in ownership of class 20, 31 & 47 BR diesel locos and back when I was a active volunteer we painted white marks across the sides of the tyres and onto the wheel hubs so that it was easy to spot if a tyre had slipped.
also lots of metro sets have tyred wheels
@@matthewutech5970 Wheelwrights use the term for wooden cart wheels which have been around since forever. A shrink fit steel tire/tyre that holds the wooden wheel together.
I had no idea the dragster burnout thing had a practical purpose with warming up the tyres for adhesion. Today I learned!
Actually the other half is to clean the tires.
Tires are soft and you don't want the small stones and powdered concrete picked up by driving from the pits (or return road etc) to be dropped along the track, That could potentially lead to a car traveling at high speed to come unstuck and hit the wall or opponent.
-You go through the water to get the tires slightly wet which helps lower traction to help all cars start the burnout.
-You don't do the burnout in the water which would spray everyone, you roll just ahead of it.
-During the burnout any small stones previously picked up from the pits are flung off and out leaving the tire cleaner and obviously allot warmer.
-When done on a street race sometimes water will be used and other times a VeryHighTraction fluid is used by pouring ahead of the wheels and the car moved into it.
-As the burnout is done the whole wheel gets coated, VHT is already sticky but it can also help break down the rubber and make it even softer and give yet more grip, As the car moves forward this helps transfer some of the rubber from the tire onto the street for a rubber-rubber contact.
Also leaves rubber on the track which provides more grip again
Very interesting. Steam locomotives have steel tires on their wheels. When they wear down, they are replaced, just like a car tire. Diesel locomotives have witness grooves in their wheels, which determine when the wheel has to be replaced. The factor of adhesion was always a consideration with steam engines. Too low of a factor and the engine would be limited in its use. Diesel and steam engines are inverse in how they put down power and all of this starts with the factor of cohesion. This is another subject, really, but it is all part of the whole.
Steel tyres can work on slow steam trains and trams but the engineering community has moved away from steel tyres after the Eschede high speed train crash in Germany. When one of the tyres cracked then got caught on some points. The tyre unrolled itself into a spear that penetrated the carriage. Over 100 dead.
Anyway steel tyres are more trouble than they are worth with machining, press fitting and the danger of them coming apart. Much easier/safer to make a solid wheel, when they wear recycle them to make new wheels.
Its amazing that train technology hasnt changed much in 300 years when it comes to wheels and rails. Other than minor improvements like welded rail its basically the same.
@@tubester4567 Yes, I know of this accident. It was caused by the tire separating from the rubber damping ring, between the tire and the wheel. They used this design because of vibrations caused by the original steel wheels, at high speed. They thought that this would mitigate the problem. This design was never meant for high-speed applications. It was never tested for this type of use. Steam locomotive tires were pressed on hot and allowed to cool, shrinking them onto the wheel. This made them an integral part of the wheel This is how they did it in the age of steam. Rubber dampers were never part of the equation on steam locomotives.
@@tubester4567 Yes, I know of this accident. It was caused by the tire separating from the rubber damping ring, between the tire and the wheel. They used this design because of vibrations caused by the original steel wheels, at high speed. They thought that this would mitigate the problem. This design was never meant for high-speed applications. It was never tested for this type of use. Steam locomotive tires were pressed on hot and allowed to cool, shrinking them onto the wheel. This made them an integral part of the wheel This is how they did it in the age of steam. Rubber dampers were never part of the equation on steam locomotives.
@@tubester4567 the do still run steel on steel tyres though. That accident had a different design that sparked the failure/accident.
@@alistairwhite2906 Only on trams and slow speed/historic trains. Many modern trains are even moving the brakes from the wheel to a separate brake disc rotor. Most of the wear on train wheels comes from the brakes.
0:15 RIP F1 not letting you use F1 footage 🤣
In the UK (And probably elsewhere, idk) trains actually do have tyres, they're just also made of steel, because it's cheaper and easier to replace the detachable band of metal round the edge of the wheel than the entire wheel.
Edit: Ok, I spelled it wrong, I get it.
In the UK they are tyres. They spell funny. (plough)
Correct. They all have tyres (correct spelling in English), it’s just not vulcanised rubber. Changing a steel alloy tyre is cheaper than scrapping a wheel.
Stream locomotives in the US had the same thing.
Trains also get "flat" tyres/tires at times This is usually from brake problems or harsh (emergency?) braking where a wheel skids along the rails for a distance without turning.
Only tyres on older locomotives , even on the 1970's class 56 we started to fit Monoblock wheels , waggons virtually all have Monoblock wheels . We did get problems with tyres if they had been heated due to dragging brakes , the tyres would move on the wheel this is why you often see white pain marks on wheels ,tyres had secondary security the gibson ring on inside of tyre
When I was a kid, I worked at an amusement park and drove the train around the park. Periodically, the rails on the turns would get greased and sometimes too much grease was applied or it would rain and the grease would get really slick and I would have to get out and sand the rails on an uphill slope.
I like trains
Fascinating.
You know who loves and knows more about trains than any other human?
Sheldon Cooper
are you acoustic
@@lbgvic135 *autistic
*TRAIN APPEARS OUT IF NOWHERE*
I'm Grady and I made a video to justify the model I build in my garage.
You are the best! I love your videos.
great video! The brush wheel demonstration about creep makes perfect sense if we think about the train braking, instead of accelerating.
Nice work in explaining creep! I always find it difficult to explain it to others without involving differential equations and material flow. I never thought about bristles on a rotating disc! That was amazing! Also a small nitpick is the stick slip illustration. The leading edge is always in stick. Only the trailing edge slips within the contact patch. As the creepage increases the slip area completely covers the contact patch as you showed.
11:37 You can see the Helmholtz waves in the vibrating violin strings. Strings that are being drawn by a bow don't oscillate like a sinusoid as you'd expect. Instead they vibrate as a triangle wave with a moving apex called Helmholtz waves.
Does anyone else find Grady's voice relaxing? I enjoy this channel for info and for the way it's presented
You mentioned cold welding and how you weren't going to get into it. But honestly, even though I've seen a few UA-camrs mash two pieces of extra-smooth metal together and - seemingly by magic - get them to stick together, I never considered the practical, engineering implications of this phenomenon. I think it would make a great video to talk about this, if only briefly.
I grew up watching How It’s Made all the time. Your videos definitely scratch that itch
Race cars generate quite a bit of aerodynamic downforce, so the friction calculation isn't only the weight of the car; it could be 2 or 3x that.
Yeah, I think that's why he started with "it's the weight" and then generalized to "it's actually the normal force which includes other things."
For the purpose of this video, I think "weight" is good enough. Trains don't usually pull a lot of G's around corners, and I venture that aerodynamic effects aren't a big component. (Though somewhere there's a good ol' boy with a spoiler on his loco...there has to be. 😂)
Im no engineer but i follow Brady and the way he presents these videos with graphics, simply amazing
Point of order: they do have tyres, it’s the outer steel of the wheel. They can be ground to restore the desired profile or rotated around the locomotive during maintenance. They can even be replaced during midlife overhaul 😃
Good add for nebula. Glad to hear it finally explained
Spent 4 years working on a metro project overseas. As an Interface Manager, now retired, between the three consortiums I had the privilege to read various train to rail test reports. At the time, and due to my background as an electrical engineer, I learned many things but not to a great depth. This video enabled me to connect several dots and several of those reports now make complete sense. Thanks for sharing.
i always wondered why locomotives experienced wheelslip if they applied full engine power when starting to move. now i know it happens from the contact patch getting less traction because the train is forcing its full tractive effort at a low speed... even as a long-time railfan im still learning new things and it really brightens my day, grady
I always like watching your videos on rail topics. The sister company of the company I work for specializes in modernizing locomotives and rail cars to make use of newer technology to improve fuel economy, emissions, maintenance costs and fleet management of rail operators. It is nice to see other people talk about the engineering in the rail industry.
I went into this video thinking: “Go ahead, tell me the ultimate reason isn’t ‘train heavy’”
3:28 Friction isn't a horizontal line, it's actually sloping down as approximated by the Curtius-Kniffler formula. At higher speeds you don't have the same adhesion as you have at standstill.
0:00 I think that's Indycar and some sort of junior open wheeler championship, not formula 1
Edit: Hey, since you're working on subject of train. Why don't you do a collab with Hyce? He's on UA-cam and his day job is an operator/engineer/fireman of a steam engine and part time mechanic/fabricator at Colorado Railway Museum
I'm going to guess that licensing F1 footage is expensive as hell.
At 0:00, yes, that was Formula 1. But then instantly transitions within seconds to the what you suggested.
F1 is quick to shut down unauthorized use of their video.
@@NorthernChev No that was indycar, but no doubt actual F1 footage would be taken down in seconds 🙄
@@Xelopheris 100%
Would have been copyright struck instantly too probably.
I know there's an intuitive component to creep, but having it explained this way helps me understand much much more.
Thanks Grady!
I have never once wondered why trains don’t have tires. But now I’m curious 😂
Haha yeah
Didn’t ask + my videos are way better than Practical Engineering 💀🤣
You didn't listen. The tires of steel wheels are steel.
@@TRUMAN_THE_TRUE_MANi watched the entirety of your catalog while wiping my bungus
@@TheDavidlloydjones I’d argue trains have wheels but no tires
I ride dirt bikes, and you mentioning F1 and tire traction made me think about Stark Varg the new electric dirt bike. A lot of people say it will be unfair because of the instant power and torque it can create, but as you said it's about the traction. You can have a dirt bike that makes 1,000 hp but if you can't get the power to other ground then it doesn't matter.
we all know you’re from the USA, but maybe you could open with „here in the USA, most locomotives have a diesel electric drive train“ 😂 In Europe diesel is not common, but this is just a small little thing 😊 great video! enjoyed watching it, including the definitely-F1-Cars 😂😊
Exactly. Even in India a diesel loco is a rare thing nowadays with 94% track being electrified.
Great explanation of how wheel creep works. My dad was one of the engineers who worked on the implementation of EMD's Super Series wheel slip/creep system. The EMD 50 series locomotives used a radar system to measure the actual ground speed of the locomotive. I know my dad worked on the radar system design and the high voltage cabinet (where the 50 series control system modules live).
Do you mean: Why Locomotives Don't Have *RUBBER* Tires? They might not be rubber, but some have separate, replaceable tires.
Came here to say exactly that
Some French trains are now sitting sad in a corner sipping there wine out of the bottle. wile looking at its rubber tires. Thinking Am I not a locomotive?
@@sirBrouwer I think you're thinking of Metro trains. I don't know of any locomotives with rubber tyres.
@@cr10001it sure is. There is one carriage that is also the locomotive. As it houses the bulk of the engine if not all of it.
Making it a locomotive with rubber tires.
Not only replaceable ‘tyres’ but they come in different ‘compounds’!
In Wellington, New Zealand, the new passenger units were found to be wearing the rail at an unacceptable rate. This was due to the bogie design making them longitudinally stiff. The leading bogie wheel was biting to hard into the outside rail in curves. The tyres having a ‘hard’ compound were grinding the rail.
Solution. Softer compound. More tyre wear, less track wear.
The down side to this was the tyres were more susceptible to slip/slide and thus often ended up with flats. The extra lathe time and shorter overall life was an unfortunate side effect.
Great post Grady. 👍❤️
"... I have a couple of demonstrations set up in my garage..." Well, that *is* why I'm here. 🙂
Seriously, your practical demonstrations make these concepts *so* much clearer. Thanks for going to all that trouble!
A good example of the stick/slip nature of the wheel/rail contact patch. Congrats for putting it in terms that doesn't bamboozle the audience :)
As a locomotive tech, I remember reading in a manual somewhere about wheel creep. If I remember right it said that adhesion increases significantly when wheels are allowed to creep at about 1-2 mph above track speed.
This was a neat demonstration of why that happenes. Neat.
We were told 7% slip/creep was the ideal amount , first loco's we had with wheel creep where the UK class 60 , this system required radar to measure speed and wheel speed sensors in traction motors . GM class 66 has a crude version of this with radar but no individual wheel speed sensing "super series " nowhere near as effective as the older UK built class 60 wheel creep
@nounoufriend1442 I do believe more modern locomotives have a system with radar and TM speed probes to measure the amount of slip. That being said, where I work we only have ancient power. The newest stuff we have are SD40-2s so I won't claim to be super familiar with anything newer than that.
"Nebula...totally ad-free!" Has there ever been a content platform in human history that didn't start out saying this?
Even on youtube, paid channel subscriptions make a lot more money per viewer than any amount of ad revenue. As a platform very open about not looking to pursue profits at the expense of UX and quality, they'd be foolish to ever include ads on their website.
Trains are amazing. I used to take my daughter to the train crossing on oir bikes so she could feel the earth shake.
She still respects the trains... And is slightly afraid of them
Some rail vehicles have tires, for example trams have a rubber ring in the steel wheel.
On June 3, 1998, an express train equipped with wheel tires had an accident in Germany. Wikipedia Eschede train disaster
The rubber ring in the wheel had caused cracks in the steel tire, high speed, a broken crack, a switch and then a pillar of a bridge led to the catastrophe. The front locomotive and the first car still passed under the damaged bridge.
But all the other wagons and the rear locomotive collide with the collapsing bridge.
Afterwards, this technology was removed from express trains.
The train line was initially shut down and later modified.
Seems to be the exception to the rule
On October 19, 1875, a steam locomotive derailed in the Timelkam railway accident in Austria due to a broken steel wheel tire.
Since the coupling broke off, the rest of the train remained on the rails. There was only material damage.
The reason was probably that the connections between material strength and brittleness had not been researched.
@@Derkiboi Engineers try new concepts. This sometimes goes wrong.
In the Enschede case, wrong decisions were made by many responsible people. And then all the bad luck came together.
The court could not find the one culprit, but spoke of the failure of many.
Ultimately, everything boiled down to monetary payments to those who were in the accident.
The contact patch size reminds me of two similar things that blew my mind when I learned about them.
The first is that steel power poles are held up only by the 4-20 bolts through them and not the large flange that more often way off the base.
The second is that all of the force holding your car up on the wheels is concentrated on 2 tiny roller bearings at a time per wheel. Not sure that the total contact area is but it's itty bitty for sure
I did not see a single F1 car until 1:00
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I actually experienced that first demonstration you made at my local gym. They're renovating and they replaced the Astroturf for the sled. Gosh is that thing HARD to push now! Before on the matted-down turf, I was pushing ~235lbs or 106.594kgs, now I can barely push 135lbs or 61.235kgs on it! Friction changed EVERYTHING and it is seriously underestimated.
Locomotives have steel, rather than rubber, tires because steel is much more elastic than inflated rubber.
This means the losses to heat from compression and rebound are much less from the flexing of the steel than they would be from rubber undergoing the same stresses.
Finally, someone else who knows train wheels have tyres. Granted most railways are moving to solid wheel systems, but wheel and tyre still exist.
Just as rubber tyres come in different compounds, steel wheels are no different.
‘Hard’ tyres last longer but are hard on the outer rail on curves. ‘Soft’ tyres are more gentle on curves but easily get flats if the get into slides.
The balance between the cost of maintaining the track verses more regular re-turning the tyres.
@@DB-thats-me I thought the video would deal with the reasons for the shift to monoblock, especially with loco's wheels. Alas, it didn't :(
you always make such clever ways to explain real world mechanisms and it just amazes me
@0:30 math isnt recreational in my state :(
Not gonna lie, Grady. this one was over my head. I’ve never taken a physics course in all my years of education and you can usually explain concepts of physics as they relate to the engineering in question so that I get them right away. I’m gonna have to watch this one a few more times. It ended and I was like, “oh…he didn’t explain it yet…”. I’ll get there
Because friction…though the Paris Metro would like a word!
Yeah the métro is unique! They planned for lots of hills I think. Good design and planning keeps railway routes flat and straight.
and notjustbikes talked about one in canada recently
What about roller coasters, which also use tracks?
@@krissp8712the Montreal metro also has rubber tires
Steel is such an amazing material. Just on its face, it's amazingly versatile, but when you think of rails that trains drive on, it's really mind-boggling what it can do.
TL;DL Reduced friction, equals reduced drag. Each wheel contact is less than the size of a US dime
I don't often say this about people, but every trip to Grady's garage is a good one!
Welp. These "formula 1" cars sure as hell were not ...
lmao fr
well, what were they??
2012/13 Indycars at the very beginning and f4 cars at 0:07
They mentioned f1 licence footage was the issue. Nonetheless it doesn't affect the video's primary topic on wheels and traction
@@Derkiboi But it affects the perception of a mistake being made.
Another hit in the world on free information for all. Thanks as usual Grady. You're truly a scholar in your crafts.
everybody should know why trains dont use tires lol is this really a serious topic?
A lot of people yes, but what about children or those who haven't come across this before. There are also a lot of places in the world with poor education.
When you're teaching the fundamentals, it's better to not leave too much out.
@TheBlazeofSteel
It was a rhetorical statement, and no reply would change their opinion.
2:20 Roller Coaster Tycoon throwback 😍
Most freights are designed to start with a progressive yank instead of a straight pull. If the full length of the train was parked with all of the 'slop' in the couplers pulled tight, the engine would not be able to start without stalling or slipping traction. You can hear this effect when the long trains stop and start.
When I was very young we lived near railway tracks. At that spot we were near the top of a notable incline. I well remember the struggles of locomotives to pull their loads, particularly as they were nearly all steam driven in those days. In rainy weather they often didn't make it, and the loco's wheels would spin up in a frenzy of rapid and loud huffing and puffing
Another thing to mention about the steel on steel design is that more flexible materials like tires physically squish under weight, and all the energy that goes into squishing the tire is energy not converted into forward motion. This is one of the reasons why semi trucks are so unbelievably inefficient when compared to cargo rail for moving the same weight.
0:44 This is not exactly the subject of the video ,but the adherence force applied by the road to the car is directed toward the inside of the curve. This produces the acceleration that curves the trajectory of the car.
Very interesting video !
Absolutely brilliant video. You can see the improvement over time in your ability to summarise fairly complex engineering concepts and present them in an accessible and engaging way.
Well as you mentioned trains can also have steel tires: They are cheaper to replace because you basically only put in a thic strip of metal, BUT you will find such wheels only on really old locomotives that still have spokes and now you might ask yourself why we bon´t use this type of wheel anymore. The answere is: Braking, yes braking. Old locos and wagons (at least in austria they would be old) use brake pads to create friction to slow down the rotation of the wheel to slow down the train and we all should know that friction creates heat and that warm metal expands so in some cases, when a train went down a long hill these tires got hot, expanded and fell of which caused the train to derail.
And that´s why Austria and many other countries use disc brakes and tireless wheels...
(If there are some mistakes in this coment, don´t hate me I´m austrian🙂)
Thanks - that was interesting. I saw another comment about tires and now I understand more about why disc brakes - interesting!
Some time I'd love to hear you discuss highway pickups modified for rail service, which use steel wheels to bear most of the weight but tires for starting and stopping.
That graph of decreasing friction the faster you go made me realize how complex high-speed trains are. Imagine the power needed to continue gaining speed at such intense rotations of the wheel
I’m an engineer for the railroad when we use sand it gives us a contact patch the size of a quarter
Hello Grady. I just bought a copy of your “Engineering in Plain Sight” book. It really caught my attention at Barnes & Noble. And now I read about this UA-cam channel. I’m looking forward to reading your book and watching your channel! 👍
3:40
I always thought they just did that because it was cool.
I wish your garage demonstrations had discussed the (significant) difference between the coefficients of static and dynamic friction. You generally don’t want your wheel contact patch to be sliding across the traction surface - this is hard for non-engineers to realize, but the contact area of the wheels of your car - or a train - are stationary relative to the surface. So the coefficient of static friction is what generally governs overall traction power.
I think he explained the difference between static and dynamic friction very well. It wasn't obvious to me in the garage model, but I know from experience that it's harder to get something moving (like a chair) than it is to keep it moving when you drag it. And his graph showed the implications of this at railroad scale.
The difference between static and kinetic friction is such a vital lesson in physics.
For the inverse reason, a cars ABS does the same thing as the train; Keeping the wheel at peak grip without slipping, in order to slow down the car as fast as possible.
that f1 analogy of soft tires for speed and hard tires for durability is incredible!
take it to the extreme and viola, hardened steel tires on hardened steel rails
Love the videos. I've been subscribed to Nebula for a long time, but I rarely go there, because when I start watching, I never stop.
1:25 Modern freight locomotives can deliver over 100 tons of TE the Wabtec Gevo is rated at 200,000 lbs starting TE and 166,000 lbs continuous TE.
Look at the video called "NS 13T Epic struggle uphill" to see wheel slip correction working its absolute hardest. Creep control is only used once the speed begins to climb above 5 MPH because of how ground speed is measured if my memory serves me right. That has a very constant squeal from the wheels being allowed to slip a bit.
"Formula 1 cars..."
(Immediately shows indycar and f4 cars)
Love your content and this video, that just made me chuckle a bit lol. I see your pinned comment and fully understand how F1 is about licensing!
The UP BigBoy series were that one giant locomotive used to move a large train. It was able to move trains up steep grades that previously required doubled engines
Some trains DO have tyres! The derailment at Eschanade in Germany was caused by an ICE (inter city express) train fitting with dual block wheels, meaning they had a layer of rubber followed by a second layer of steel over the wheel. This provided some cushioning to the wheels, minimising sound and vibration before the invention of continuously welded rail. However, poor/nonexistent maintenence led to the outer layer of steel coming loose and getting stuck in the train body, and forcing a derailment when it encountered a junction.
That was an unusual design. The majority of wheels (that aren't monoblock) have steel tyres shrunk direct onto the steel wheels. This was universal for steam locos, and probably a majority of diesel/electric locos in Europe. The derailment was at Eschede, by the way.
You ARE correct Sir!
You should look into drag racing cars that use that slip curve to their advantage as well. Especially in the lower speeds as they launch. It’s fascinating engineering used there as well.
Whatever the subject matter: Nothing beats a presenter that is passionate about the topic (s)he is talking about.
This channel and other educational youtube channels are the best I wish more people took the time to learn about the world around them.