Busting Tractive Effort MYTHS! | Railroad 101
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- เผยแพร่เมื่อ 28 ก.ค. 2024
- Tractive effort is a pretty simple thing, yet it always seems enshrouded in mystery. Let's try and clear things up today.
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0:00 Intro
0:36 What is Tractive Effort?
1:52 The Equation
2:45 Myth 1: 0.85 Cutoff
5:12 Myth 2: Sand
7:11 Myth 3: Drivers and Weight
8:27 Myth 4: Bigger Drivers?
9:37 Myth 5: Speed
11:14 Myth 6: No way to up it
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One thing that's seldom mentioned when considering the T.E. equation is that you get the maximum tractive effort when the cylinders are bored out almost to the condemning limit (3/4-inch oversize for a PM Berkshire) and the driver tires are likewise almost at the tread worn too thin limit (4 inches under nominal for that same PM Berkshire). This can add a surprising amount to T.E., but also makes the engine more slippery.
Very true! Good point. That would've been a fun thing to include directly in the video.
This reminds me of the C&O Alleghenies. It's said that it exerted up to 119,500 lbf of tractive effort with worn 65.5" drivers.
So a worn out engine basically will pull hardest if I am understanding you correctly?
@@Hybris51129 The trouble with a worn-out engine is that K = 0.85 is probably lower on account of the mean effective pressure in the cylinders through one stroke being lower on account of deferred maintainance.
Every railroader knows that turning on the bell and “generator” gives a 10% boost in tractive effort when climbing the switchbacks to the iron mine.
don't forget pushing a snow plow in front of you gives a 10% boost in top speed.
I almost made a joke about that in the video but figured it'd be more of a hornets nest kick than a joke for some... Lol!
Ah yes, the bell, activated by “hand valve”
They would get another 10% if they painted them red
The same way a fire engine is actually powered by its air horns. LOL
To quote Adam Savage: “I REJECT YOUR REALITY AND SUBSTITUTE MY OWN!”
and Jamie: "QUACK DAMN YOU!"
Hyce as Jamie: Hyce want big Kenosha (in games)
Which is a perfectly valid thing to do. Time is fake and space is a bad idea.
I once murdered the backs of several unimportant pieces of junk mail trying to work out where the bloody hell that 0.85 came from. I got as far as pi/4 had to be in there somewhere before throwing in the towel. Thank you for the explanation and the general nerdiness. I love getting in the weeds on this stuff. Great video!
PS: here's my vote for a video about curves, hills, and other things that affect the on-paper tractive effort.
I believe that coefficient is just something to make the numbers fit the real behaviour of locomotives because it is all linear. If this formula would be precise, the coefficient would be 1
It's clearly more of a "this is to account for the unaccountable variables" number. Theoretically, it could be any number of values, because it also doesn't account for things like the condition of the locomotive, as it assumes everything is in 100% working order.
@@pi0neer758 No, the coefficient should not be 1, because the ideal equation has to include pi/4 because the cylinder has a circular cross section and some other numbers to account for the fact that the engine has two cylinders 90 degrees out of phase.
It's simply the K adopted by the American Association of Railroad Master Mechanics in about 1900 or so - and reflects numerous indicator card tests as to what the mean effective pressure was through one stroke. It's imperical rather than theoretical.
An ES&DT logo on the tender can give a +15% to top speed but a -20% to stability, (-35% if an aroma of "Kenosha" is detected).
Lol
One of the sounds I shall never forget is a drawbar breaking. Another is a trio of 10,000 amp fuses blowing from a bolted dead short. One was a huge very loud ka-blam, and the other was little plinking sounds. Both were really expensive.
As a Mechanical Engineer, I can say that yes: when we all argue in favor of larger driver diameter, we are assuming that the driving rod position maintains the same ratio of the driver radius, and doesn't maintain the exact same distance from the hub, which would naturally necessitate an increase in piston travel. We intuitively know it would work, even if we miss which is the driving variable.
Actually, if it's the same ratio it makes no difference. What you want is to have it keep the same distance from the outer rim, so the ratio goes down. :)
Layman´s terms:
1) Tractive effort: the maximum weight of your car that your engine can power without choking and dying
2) Adhesion: are you able to use that power without spinning the wheels?
3) Drivers´ size: final gear -> big = more revolutions, needs more torque
4) Piston stroke, surface, pressure: torque
Lesson:
1) If you want to tow a cargo ship, your super ultra tuned, high tractive effort semi truck may not be enough if it has only one powered axle (and low weight), as it would overcome the adhesion limit of its tires and produce only wheelspin.
2) Converting your cheap little grocery-getter car into all wheel drive won´t increase its tractive effort. In fact it may decrease it a little bit (due to increased inner friction). But it may help on a slippery surface.
3) Higher gear (bigger wheels) is only good if you have enough tractive effort and adhesion, and just want to go faster.
Thanks. This clears up a lot of my questions. Less confusion for me!
Meanwhile Jeremy Clarkson towed a ferry 100m with a grocery getter.
@@kornaros96 Ferry is surely nothing like a cargo ship. Anyway, if the car has enough torque and adhesion to overcome the resistance of the water, then why not?
Since you mentioned diesel, I thought I'd do my own nerding out, lol.
In diesel locomotives, (I'll only mention those with DC traction because I'm not remotely qualified to talk about the minutia of AC traction) your tractive effort is related to your traction motor amperage. (I think you actually mentioned the approximation EMD uses in your other video. The equation that uses horsepower, a constant, and divides that by the speed) As such, you get the most tractive effort with the motors at (or near) stall. The nerdy part and nuance comes into play when you consider low speeds and how the excitation system works.
Starting simple, diesels have a spec called "minimum speed for full horsepower" (which depends on the gear ratio selected by the railroad) Above that speed, the approximation of tractive effort based off horsepower works pretty well, but below that speed the actual tractive effort will be less than the equation says.
This is where the complexity (and my nerding out) begins. So as the motors slow down, they draw more and more current, which means we get more torque out of the motors. But, it also means that the motors and main have to pass more current, which causes things to heat up. As such, the excitation system is designed to limit the current from the main to help avoid overheating issues. Above the "minimum speed for full horsepower," the load regulator and excitation system will work to keep the engine running at full horsepower (or a constant horsepower based on what throttle notch you're in). However, below that line the excitation system is designed to "override" (sort of) the load regulator to (try to) keep the current in the main at a relatively safe level. The excitation system does a similar thing at high speeds, except it's limiting voltage instead of amperage. So, (ignoring transition) if you were to watch the load regulator on a locomotive in 8th notch at a high speed as it pulled up a hill to a stall, you see the load regulator start out at "full field" because the excitation system is limiting the voltage from the main and the engine isn't producing full horsepower. Then, as things started to slow down, the excitation system would allow for more horsepower and eventually the engine would reach full horsepower, at which point the load regulator would start to back off a bit to keep the engine at full horsepower. As you continued to slow down, eventually the load regulator would start to move back to "full field" position as the excitation system starts limiting current from the main. Once you reach the "minimum speed for full horsepower" the load regulator would hit "full field" and then the excitation system then gets control and starts limiting the current from the main. At this point, you'd start losing horsepower again as the excitation system is designed to protect the equipment from excessive current.
A cool thing about Dash-2s, is that some of them were built with a different PF card, which has an additional "performance control" curve which allows the locomotive to load harder at those lower speeds, but now you're relying more on the engineer to keep the current to a safe level for the sake of the equipment. And those "performance control" curves don't affect the normal operation of the system above the full horsepower line.
That's a lot of words and not a perfect explanation, but I wanted to take the opportunity to nerd out a bit lol.
When figuring the tractive effort of a steam locomotive, I’m thinking one should use inches when plugging in the diameters of the piston and drivers into the equation?
@@billmorris2613 Yes. The working pressure of the boiler is in psi, so multiplying by square inches (diameter squared) will give you force.
@@CDROM-lq9iz Thanks.
Albert Einstein said that the deffinition of Genius is someone who can take the complex and make it simple
thank you hyce.
He also said there is a fine line between genius and insanity. I like to think many people that do the choo-choo stuff in their spare time walk tbat line.
Far too kind my friend, thank you :)
@@PowerTrain611 But _did_ he say that? Most of these supposed Einstein quotes are complete fabrications. If I tell you that Einstein said, "Embrace each challenge as a stepping stone to your greatness," you'll think it's much more significant than if I tell you the truth: I asked ChatGPT to make up an inspiring quote of one short sentence.
@@beeble2003 You bring up a fair point. But I read this quote long before ChatGPT was even a neuron firing in the neural network of Sam Altman or Elon Musk, and before most people were connected to the budding internet.
That's not to say it's not possible, but I like to think it's true. Einstein was known to be a bit of a goofball at times, and that's part of the way I interpret this quote.
It just seems like something he would have said.
@@PowerTrain611 I'm not suggesting that the quote was written by ChatGPT. Just that an awful lot of what is attributed to Einstein was never actually said by him, and just had his name tagged onto it to make it more popular.
I instantly recalled the Drivers video you did some months back on the 4th myth, and recalled you saying "Generally, medium to large wheels were used for passenger service, and smaller to medium were generally used for freight service, but this isn't always the case." Nice to see a bit more train mythbusting
11:34 Ah, the booster engines I learned from ToT; I'm glad they're still in preservation.
That is my biggest frustration with that ToT video, he sort of concludes with "well the booster never worked in Britain really so it wasn't that great if an idea" while glossing over how many engines in the US still have them. 🤦♂️ToT is good overall, but there are a few moments like that where he either needs to look out at wider global history and expand his horizons, or admit his focus is primarily on British stuff and keep his focus there.
One of the other things that affected tractive effort especially on engines with long dry pipes was head losses in the dry pipe. Willamette actually used a factor of 0.75 for their saturation engines to account for losses as the steam ran from the throttle, out the smokebox, and then did a U-turn back to the cylinders on the side. To my knowledge they used the normal 0.85 factor on the superheated engines because the hotter and dryer steam didn’t experience as much loss
11:14 Let's also not forget rebuilds. You can rebuild a locomotive with larger or smaller drivers, bigger cylinders, and/or a higher-pressure boiler. It's probably a bit outside the scope of most people's thoughts on railroading, but it's definitely possible.
Yes, 2102 actually started life as a 2-8-0 and then got rebuilt to a 4-8-4.
@@awildjared1396 I didn't know that, I'll need to look into it, it sounds interesting. Thanks.
EBT 16 got a higher pressure boiler in its last rebuild, so I assume it's tractive effort changed as well.
@@jacoblyman9441 I would have to agree with you.
B&O converted 2-10-2 Sante Fe boilers to use on their 4-8-2 Mountains, as well as Mikado 4-8-2 boilers fitted to 4-6-2 Pacific frames. I am sure other roads recycled locomotive parts all the time.
me when i go up a hill and i lose all my tractive effort
*stares at the PRR* Truer words could not be said lol
Great video, Hyce! Thank you for the tractive effort explanation and mythbusting!
Cheers my friend!
LOVE THE STARE AT THE PRR
THE DECAPODS (( 2-10-0 ))
A LOCOMOTIVE THAT WEIGHED 386,000 LBS
62 INCH DRIVERS
240 LBS BOILER PRESSURE
YET KICKED OUT 105,000 LBS T.E.
13,000 MORE THAN
U.P. CHALLENGERS
250 psi boiler pressure
@@09JDCTrainMan depends on if your talking as built ,,
Before superheated , with the extended pistons that went forward through the piston heads . Before the Worthington feed water heater and stokers were added ..
YEH , THEM MONSTERS WHERE HAND FIRED WHEN BUILT ......
As built , boiler pressure was 190 lbs on the first ,,
205 lbs on the second ,,,
I1 , I1s or the I1sa
Then the larger tenders were added .......
I had a good friend who drove GG1s for the PRR and later Amtrak. He told me once that a steam engine can pull a train it can't start, and a diesel locomotive and start a train it can't pull, but the GG1 had no such limitation. What a shame they are no longer in service.
Having more cylinders would also increase tractive effort, all other things being equal. Not an issue on most US locomotives (other than adding together the tractive efforts of the otherwise conventional engines on articulated locomotives), but then Southern Pacific had their 4-10-2 locomotives and Union Pacific had their 4-12-2 locomotives, both of which had 3 cylinders. This would also increase the maximum usable tractive effort by somewhat smoothing out the variations in torque through the cycle.
And yes, I would like to see this for diesel(*) and electric locomotives.
(*)Mainly diesel-electric, but then you have those diesel-hydraulic weirdos like the Krauss-Maffei locomotives that the Southern Pacific and DRG got in the 1960s, as well as many in Europe; and then you've got that compact switcher at the Colorado Railroad Museum.
Edit: Also let's not forget geared steam locomotives. Hmm, maybe we need *2* more videos . . . .
Yup. For what it's worth, the Union Pacific also had some 4-10-2 locomotives that were nearly identical to the SP's, but they found that amount of that extra tractive effort they could actually use wasn't worth the increased maintenance costs so they rebuilt them as two-cylinder locomotives.
I finally understand how caprotti valve gear works. It essentially makes the cam lobe last longer in the corner and makes it shorter hooked up by using 2 lobes that rotate.
That sounds about right. You've been doing your research!
@@Hyce777 Franklin valve gear is turbo cursed
I was really confused when someone said they preferred a 4-axle French electric loco to an English 6-axle loco because it "picked up from a standstill easier". I always thought more wheels meant more contact patch meant more grip.
But now you've explained all this, I guess it was all down to axle loading. The French loco weighed 20.75 metric tons per axle while the English loco only carried 16.67 per axle.
TE is an awesome topic, i remember the Derail Valley video on the S282 multi wheel arrangements, from the 4-4-0, to the 0-12-0, my fave was the 2-10-0 (i think that was it, idk) but i remember the smaller wheels having more tractive effort, and if my feeble simple brain can simply put it, smaller wheel, shorter stroke, the shorter the piston has to stroke, the more (or less i think) effort it has to put in.
love all the videos as always Hyce
Most interesting & educational.
Been into steam and early diesel for over 55 years.
Thoroughly enjoy your channel.
All the best from Scotland. 🏴
It’s cool to hear the full explanation for why TE math works the way it does. I’ve heard you and others give some of the story before, so thanks for completing the lesson with this video!
10:45 there is a video series on youtube called Astley Green and Walkden railway and because of mutiple factors the mine would close down if they didn't get enough coal, the gradients on the line, the fact the locomotives were rented and were Austerity 0-6-0's which were meant to last a few years in WW2 yet are there in the 1970s and a very sturdy loco. They are pushing the locos to the limit and it's quick impressive seeing them chug along wheel slipping and huge plumes of smoke with a long train of full coal wagons behind.
Excellent video. Definitly needs to be part of any steam locomotive class.
It's interesting reading railroad engineering books about the wheel and rail dynamics. Steel is elastic, so the contact area between the wheels and rails changes depending on the steel types and weight. But generally speaking, more weight per axle means a larger contact area; conversely, less weight means a smaller contact area. It works out that a locomotive with one drive axle with X weight versus a locomotive with four drive axles with a total of X weight has nearly the same total contact area between the wheels and the rails. This is why the number of drivers isn't as important as one would think.
That's interesting! I'd imagine tire hardness plays a lot into that as well. Makes sense.
@@Hyce777@Hyce777 Yes, the hardness is important. The higher the hardness, the less elasticity in the steel, and the less traction can be developed. If the wheels/tires are too soft, they'll have good traction but wear faster, increasing repair downtime and raising maintenance costs.
Also, the harder the wheels, the faster the rail will wear down. Thus, the railroad must balance how often it wants to replace rail vs. wheels.
ASTM (A-504), AAR (M-107), and APTA (PR-M-S-012-99) each have standards for metallurgy and hardness of locomotive and car wheels depending on expected speeds and braking forces.
In Grand Scale trains, car wheels are typically made of high-carbon steel and have hardened treads, while locomotives have medium-to low-carbon steel tires for increased traction.
@@CurtisFerrington : Also, to a first approximation, friction is proportional to the weight applied, and not proportional to the size of the contact patch. I suppose that there are second-order effects there, though, as well as effects on durability and rail wear, though?
I'm so happy there are still nerds like you in this world who explain nerd stuff that no one else cares to explain. 🙏
Larger drivers=more slippery locomotive? Should also note that on the first group of Pere Marquette Berkshires (class N), crews reported difficulty in keeping water on the crown sheet when the booster was working. Apparently these locomotives could make and use steam faster than the boiler could be supplied with water. Subsequent classes (N1 and N2) were not booster equipped.
As always a big thumbs up. You provide a great deal of information to the general public.
Yes I knew it, what an awesome video Hyce 🔥🔥🔥💪🏻 it was so *** amazing. I loved the (mythbusters)theme in it 🤟🏻
Same arguments are all around hull speed and the relationship between drag Vs power and propellers on boats. Gets back to the ideal bigger isn't always better. Can be applied to just about anything in life.
Only tangentially related, but you NEED to come out to Pennsylvania and see 2102 in person. I got to ride behind her last fall and will be doing so again later this month. She put on a SPECTACULAR performance. That video of her charging out of Port Clinton? It's even more incredible in person.
I've thought about doing that this fall when I have a week off.
‘Train of Thought’ made a video that discusses the history behind the pusher/helper truck. Highly recommend to watch it for more examples and explanation on how it works.
Thankyou for clearing this up!!! Such a cool series I always thought Biggers wheels more TE, I'm glad I was corrected, love the videos!!!
I love these kinds of videos, the math, logic, and principles behind the mechanics are the most interesting part of steam technology to me.
This definitely helped me with some locomotive designs I have that have no way of telling the tractive effort
Very informative video answered a lot of questions I had about it
A rule of thumb: large driver size increases (practical) speed, small driver size increases effective power. Hence why the D&RGW narrow gauge stuff is really slow but powerful, and why the Stirling Single was known for express running and not freight
One of the most impressive tractive efforts I've seen on a locomotive is the EAR 59 class it has a tractive effort of 83,350lbf which at first might not seem that impressive until you realise it's a narrow gauage locomotive
Thank you for a great mini lecture on TE. Have always wondered about all of the mechanics and math behind TE. Appreciate the formulas for computing TE.
It would be great to see one on calculating diesel electric TE.
Great video, never understood TE before, but very well explained, thank you.
I love the thumbnail, Of the little American Standard locomotive turned into a 12 wheeled monstrosity. And as always the video is very enjoyable and informative. Since I’m writing a book about dogs and steam locomotives, I’ll tell you more later, I have to learn as much as I can about railroading. Thanks and keep up the good work.
Thanks for that, Hyce, very informative.
Booster engine is a neat idea!
Loved the D&RGW clips early in the video 🎶
Beating the ROW to pieces? (Glaring at 1920s D&RGW engine purchases)
1:11 - Thanks for illustrating why measuring the force in Newtons and the mass in Kilograms is less confusing than measuring both in Pounds =P
2:10 - The .85 coming from the cutoff …? Or what are they?
2:50 - There's the answer.
3:15 - Or is it?
4:50 - There it actually is. xD
5:17 - I can't even commence to understand how that myth can come around. That's so obvious in my eyes. And yet, you're right, it does seem to be a common misconception.
5:56 - To be a bit nitpicky here (and acknowledging the possibility I misconnect some dots due to language stuff; sometimes terms seem to be literal translations yet mean different things), the rolling friction (aka rolling resistance) is way lower than that and not that relevant in this instant. It's the static friction of the (not slipping) wheel on the rail that limits the force transfer from the wheel to the rail (and thus from the engine to the Earth). And boy can it get low. For good, dry conditions .25 is even rather conservative - but we're talking steam engines with tons of lubricated moving parts on the outside and, you know, steam, so I'll guess a steam engine rarely is on actually clean, dry track. But I've witnessed situations where it barely was above zero. Leaves, certain types of pollen, certain types of industrial dust (both aforementioned especially when combined with beginning rain after prolongued dry weather), birch leaves (those deserve an own mention apart from leaves in general) and actually swarms of dead butterflies can be really nasty.
6:45 - That higher value being generally cited at somewhere around .4 to .45 under dry conditions. Bad conditions will always be better with sand than without, but they'll still be lowered. Wet, dirty rails will often end up somewhere around .25 *with sand* in my experience (200 kN becoming often the limit of feasibility, 84 t locomotive mass, my local gravitation is 9.81 m/s² -> friction coefficient calculates as 0.2427).
7:50 - Adding to the structural frame conditions of the railway itself there's also only so much force the couplers can take. Those you use on your pond side tolerate significantly higher forces and yet also there you get to the point of needing distributed power etc. instead of just yanking everything from the front. But apart from that; the number of drivers thing is more or less an issue specific to steam engines and in vastly smaller amount to historical or special cases in the other traction types. Usually and especially in modern day locomotives all axles are drivers, so while there might be other benefits to spreading the mass over more drivers (again, the trackage itself; size of motors; calmness of the ride etc), the tractive effort doesn't care if it's two axles or three bogies with three axles each.
9:35 - For those who like to see things through equations, you can also put it this way: One stroke of a given cylinder can only do so much work. No matter what happens after the piston, the given amount of steam at the given pressure has a given energy. Also, no matter how big or small the wheel is, one piston stroke (back and forth) is one rotation. And now if you remember mechanical 101, there's the neat equation of W = F * s with W being the energy (or the work), F the force and s the distance, in our case the circumference of the wheel, which again is proportional to the radius/diametre. Resolving for F, you get F = W / s and thus, given W being constant, F is proportional to the reciprocal of s. Doubling s halves the force, halving s doubles the force.
12:45 - Well, I'll say electric traction is a lot more straight forward. The transformer and the asynchronous motors have their maximum power. End of story. P = W / t = F * s / t = F * v; in other words, F = P / v. The faster you go, the weaker you are.
As always, well explained and understandable. You really make those topics far more accessible to "outsiders" who want to know more. Also for me with my own professional background in railway operations myself, but with no deeper connection to steam era stuff there's always a lot to learn from your videos. Only reason there wasn't much new for me in this one is that I've learned most of it from your other videos before.
Great discussions mate. The friction pieces are spot on, on your end as well. 0.25 is pretty conservative, but a lot of steam stuff had varying degrees of hardness in the tires back in the day which was part of where that comes in. But yes, pounds and poundforce.... imperial units are stupid.
Glad to hear some of the context in modern-day electric railway terms, and glad that I could help explain at least a little something. :)
That 3-chime at 0:29 is gorgeous (at least I think it's a 3-chime).
Also, I didn't know that Reading 2102 had a booster. That's really cool. Maybe a video idea for the future is one covering boosters and the different type. I think that would be a cool idea.
One question about boosters on the subject, as for RBM&N 2102, where does the exhaust steam for the booster come out? I've never seen any coming from the tender, and to me it would just seem impractical to pipe the booster's exhaust from the tender all the way to the smokebox.
Anyway, love the video, and I had a few myths of my own busted. It was a ton of fun to watch!
They drop out right next to the booster itself. The big plume of steam from the rear in the videos of 2102 working hard pulling the coal hoppers is the easiest to see it.
Also that's the DT&I 5 chime. One of my favorite whistles.
When the PRR tested the I1s using 50 percent cutoff, it measured more TE at speed (35 mph) than starting TE. When they changed the valve setting to 65 percent cutoff making them I1sa is when starting TE equaled at speed TE. It also lowered the FH on start up but at speed it was better than the modern 4 cylinder locomotives.
Good job of explaining the math. Thank you.
Steam locos also have a tractive effort curve. Long-term horsepower (and therefore TE at a given speed) is determined by the ability of the boiler to make steam, but instantaneously you need to consider the difference in pressure on the two sides of the piston. At speed, reducing cut-off reduces the amount of exhaust steam you have to push out of the cylinder and thereby reduces back-pressure.
There's also cases of tractive effort being decreased on locomotives, like the P2 2-8-2 being turned into the A2/2 4-6-2.
Love your videos man!
The booster is a really ingenious work-around for that TE equation, and in some cases makes sense. (That’s the real 10% extra power….not the bell. 😂) Seems like it is only a thing for some of the larger examples.
Many of the larger examples, really. Tender boosters are quite rare, but a surprising number of the heavy-frame outside-bearing trailing trucks have booster engines hidden inside. Even the single-axle ones.
A very nice way to end the weekend, class time with The Professor! Hi Mark busting myths is always a learning experience, gets us to rethink for the better things we have heard and internalized over the years. Reminds me of the history myth that people were shorter during the American colonial period-they weren’t, actually, height was the same as presently. But I digress 😁. Mark, your explanations for this novice were excellent, clear and concise. The inclusion of math was appropriate and necessary because it only enhanced what you were saying about tractive effort (and this is coming from someone who, shall we say, doesn’t get along well with math). But like you said that’s what a calculator is for! 🤣 As always Professor I learn so much through your 101 classes. Many thanks again for this wonderful learning moment, looking forward to the next 101, and cheers to you!
Great video. Informative as always.
Really nice to find someone who can think like this guy.
Great explanation Mr. Hyce!
For a future video could you talk about the bottom dump gons and how they work?
Hyce: "Historically, railroads used a reduction factor to run their locomotives at less than maximum capacity."
Me: Laughs in Southern Pacific, which was apparently known for loading their diesels to the point of crawling up the grades at walking speeds in Notch 8 and thus completely toasting the traction motors.
The SP was a special brand of stupid.
I think what the majority of mechanical engineers meant by "Bigger drivers" was having a bigger driver so you can move the main rod connection towards the edge which would give you more piston stroke thus increasing TE
No. It's not driver height, it's driver circumference - and a larger driver circumference decreases TE.
Driver size has nothing to do with where you connect the main. Sure, there's more room to move it out on a bigger driver, but that's not the direct correlation. Wacky stuff.
@@Hyce777 the having more room to move it out was my point there
You have a limited stroke from the cylinder. If you went to bigger drivers and moved the rod to the outside edge you’d end up over stroking the cylinders.
Basically where the rod connects to the wheel is set by the stroke of the cylinder so for a particular engine all driver sizes would have the same rod connection.
Apparently the GWR's top express locos, the Kings, were based on the Castle design but actually had smaller drivers to increase TE.
Great info .I've seen them sand the rails at Disney .cool to watch the process . thank you Have a great week
Any time I see videos on the mechanics of steam locomotives, I keep thinking we need a railroad-themed game like Automation where we can play with all of the factors that go into design of locomotives. Bonus points if you can then export your creations into a simulator to see how they perform 'in the field'. (Like how you can export your Automation cars into BeamNG and drive them)
Thanks for all of the insight into the wonderful world of railroading!
On class 1's, you can change the EPA (Equivalent Powered Axles (A rating of force multiplied by 10,000lbs pulling force)) by simply changing the paperwork. Ive had plenty of 12.2 EPA AC locos that turn into 14.4's when we setout an engine in the consist that has DC motors....
Canadian Pacific 2-10-4 Selkirk locomotives also had Booster engines. These were the biggest steam locos in the British Empire.
You have.
To remember one thing, steam has no limit.You can generate steam until you blow the boiler up.But as far as power and forward motion or reverse motion steam has no believant
Speaking of tractive effort,
can you do what is the strongest locomotive with the most tractive effort for the next video.
This video is interesting it's gotta be my favorite because duhh choo choos, but it's cool to learn what can a locomotive does.
Very good video. Well done.
Hey Hyce! A video idea for the future, you could show your honest opinions for the new Hydrogen Powered Locomotives! (It would make for a funny video!) And maybe talk more about some failed types of locomotives! Thanks for the amazing content! - Em Railfans
That sounds like a fun idea!
Owner of company I worked for believes the rails bend slightly under the wheels and "cup" them due to the wooden ties thus more traction than if using concrete ties.
11:16
There is one other thing! And that is called "piss off the FRA and put something heavy on top of the safety valve"
More boiler pressure, more power!
Lol, well, that's against the rules. Also I'm pretty sure setting something *on* the safety would cause it to pop. You'd need to gag it.
That was something done in the early days of rail travel, and every one who wasn't killed outright by the ensuing boiler explosion quickly called it a bad idea.
Thanks for giving us a fantastic list of things to say in chat to make you blow your safety Mark!
The term "tractive effort" is decieving. It makes it sound like traction is involved when it is not involved at all.
It is poorly worded, I agree.
This will be so realistic thanks hyce
Babe wake up a new Hyce 101 dropped
Nice Lesson Prof.DDr.Master Bachelor of Train Engeneering Hyce.
question is there a way to submit messages or Ideas to Mark from studio 346,
for future projects?
I forgot to ask on the RhB grand scale video from Comifornia.
Feel free to shoot me an email at the channel email.
Steam locomotive "boosters?" That's new to me and here I thought I knew everything.
Yup! When they were new to me, I had no idea how common they were, because (aside from the quite rare ones on tender trucks) they hide out of sight. But quite a lot of the larger locomotives have trailing-truck boosters.
Great effort, will pull me back here :)
The maximum allowed axle load of course depends on the lines where the locomotive will operate. Each line having a limitation there (in continental Europe there are classes A, B, C, D from light to heavy with subclasses about weight per meter for bridges).
Back in the steam age for a long time the military required all Austrian locomotives to be used universally in times of war. That and the limited length of turntables put pretty severe restrictions on the growth of locomotives and lead to ingenious constructions. For example the first locomotive with five coupled wheelsets, kkStB class 180 (built from 1901) designed by Karl Gölsdorf with just 13.5 t axle load. Distributing the load over five wheelsets allowed it to have sufficient tractive force anyway (though I can't find the kN in my sources).
Even today some locomotives aren't permitted on certain lines for which they are too heavy.
Imagine a loco with 10ft wheels and it’s like a 4-2-2 that would a really powerful or fast locomotive
It be fun to relate real-world railroading to model scale in HO to see if real-world models react the same or similar.
You should do a video that explains transition for diesel locomotives, one of electricians compared it to transmission on a car or truck we had GMD 1s that we could make fourth transition on the shoptrack
Greg , retired machinist of CNs Transcona main shops .
(I know this is a lot of text, but it's a pretty abstract idea so I wanted to explain it throughly)
The 0.85 coefficient isn't calculated from the area of a circle and/or area under a sine curve.
Literally every singe possible variable affects the tractive effort of a locomotive, so you would need to know the entire universe to get the correct tractive effort. The formula just includes the major elements that affect the TE. If the result should increase when the value increases (like boiler pressure or piston diameter), you multiply it, if the result should decrease (like wheel diameter), you divide by it. of course you don't multiply it directly, you do it with a coefficient that is determined by the effect it has on the TE, but you don't need to know it, that's why it's beautiful. When you multiply all the elements and coefficients together, you can simplify the coefficients into one. Now you wouldn't know what this number is because you don't know the numbers it came from. The way you find it is by getting one locomotive, getting the variables you have in the formula, and putting them in, then you get a number. After that you actually measure the TE of the locomotive in real life, by whatever method and you get it's TE. After that you have to find "what number multiplied by my result will give the same number I measured in real life?". And that's it. Assuming you have all possible variables in the formula, it will be perfectly precise for _any_ locomotive. Of course the formula we use doesn't have all possible variables, so we need more real measurments to get a more precise aproximation.
What is even better is that you can put any measuring system in the formula, calculate the new coefficient from the real number and the one your formula has, and then it just works.
thanks for reading my book :-)
Well said my friend, thanks for the cheers! Yeah, it's impossible to classify *everything* that influences it, and lord knows many manufacturers altered their coefficient based on things they learned experimentally.
and here i thought that tractive effort already includes the FoE. well you learn something new every day
Learned a lot as I am information deficient. I wonder how much fun it would be to take a lesson from the old Boeing B 47's and just add a jato
12:06 ah cool another excuse to head down and stare at 4449 some more
8:27 The bigger wrench idea only applies when you're exerting force from the end toward the center. Take a board and put a weight toward the middle and lift from one end, keeping the other end on the ground. Pretty easy, right? Now swap the weight to the end and lift near the middle while still keeping the other end on the ground. Much harder because you'll need 4x the force as lifting from the end.
(For my example, I imagined a 10 ft board and 100 lbs weight. 100 lbs at 5 ft is 500 ft-lbs, to make 500 ft-lbs force at 10 ft only needs 50 lbs force. 100 lbs at 10 ft is 1000 ft-lbs, to generate that at 5 ft distance takes 200 lbs force, or 4x as much. Really, you'd need more force either way to actually lift the weight, but that's beside the point.)
I feel like this is something that would have been a segment on the kAN and Hyce Traincast a while back. I have my hopes it will return with Century of Steam :)
Hyce I got to see Midland at the EBT yesterday for a 4.5 hour trip. He said you might go there in mid September.
That's the plan! Yeah. Glad you got to meet him. He's delightful.
More stories from Interbay that involve Mr Smiley please and thank you :D
I come back from a long gameing break and hear “weight”
Me: pauses vid
“Ok, mark. I am waiting.”
I was taught many years ago, in a very simple way, the larger a steam locomotive's wheel diameter, the faster it can go, but its harder to start a train from stop. The smaller the wheel diameter the slower your top speed, but starting a train from stop is easier. I know all the other things mentioned play a part as well.
That's pretty much it. Like he said about the bigger wrench, but backward. With a wrench, you're applying the force to the center from the end. That's why you get an increase in torque (100 lbs force at 1 ft from center is 100 ft-lbs torque, 100 lbs force at 2 ft from center is 200 ft-lbs torque). But when driving from the center, distance decreases your torque output (100 ft-lbs torque from the center at 1 ft distance exerts 100 lbs force, 100 ft-lbs torque at 2 ft distance exerts 50 lbs force).
I definitely would like to see a version of this for the diesels.
Heres an idea. If you could go in depth about how diesel power works I'd love to hear it
To be fair I kinda think that the myth of sand adding more tractive effort might be due to a mixup when talking about which tractive effort people are talking about. Yes it doesn't increase the tractive effort an engine is rated as it's maximum. It can increase the tractive effort it is producing when viewed in the current moment based on adhesion. On slippery rail the maximum possible tractive effort is reduced, but adding sand raises the tractive effort the engine can actually produce in that moment closer or maybe even up to it's rated tractive effort.
Just a thought on where people might get mixed up.
MOM HYCE UPLOADED A NEW VIDEO!!!
Thanks, really interresting information :)
In regards to the wheel size, if it doesen't give more having them larger, why do many steam locomotives have large wheels?
Tractive effort is determined by total weight on drivers times coefficient of friction which is determined by rail condition: rust, wet, icy, foliage on rail all lower the coefficient. Typical TE on clean dry rail is 0.25 X weight on drivers
Tractive effort is determined from the characteristics of a locomotive: piston dimensions, boiler pressure, and driver circumference. Factor of Adhesion affects the ability of a locomotive to make use of that tractive effort at startup through to 8-10 mph when tractive effort drops away whilst adhesive weight remains constant.
@@theimaginationstation1899 Potential TE is useless without adhesion. Maximum possible drawbar pull is determined by adhesion. Engines have been made that produce above and below their adhesion limit - the ones above are "slippery" but cannot pull harder that their adhesion allows. Locomotive specs always list the max TE as the lbs. it can pull based on its weight on drivers time the COF. Most locomotives are designed with more potential so that they can maintain pull at high speeds - all of this goes for diesels too.
@@Hogger280 I don't necessarily disagree with you. All I can add is that the idea of more potential at high speeds - hauling more, faster came at a time when tractive effort at starting, which is what the equation gives was less important than tractive effort at road speed, and thereby horsepower at the desired road speed.
Tractive effort, though well understood by the locomotive designers et. al (certainly they understood that K=0.85 referred to MEP) never really achieved the significance that it seems now to have on internet comments sections.
@@theimaginationstation1899 There it is - what you were getting at is Horse Power, which includes a rate of applying the force and what I said in my comment - "designed with more potential so that they can maintain pull at high speeds"
@@Hogger280 Absolutely. The intersection of the line of the train's resistance, the line of diminishing tractive effort as road speed increases, and the line of increasing road speed. Thus the happy area of hauling more, faster. The conundrum is that a higher tractive effort at the desired road speed means that the factor of adhesion is compromised at starting speeds as tractive effort is at its peak - thus boosters, three cylinders, improved sanders, front-end throttles and the like.
For passenger locomotives like the Hudsons the fact that starts and stops were infrequent on their daily runs meant the roads were prepared to live with a slippy start for better performance at speed.
About part 2:
The actual _at_rail_ tractive effort is a minimum of two values. The first is the effective force applied by steam pressure at the pistons, which is covered by the true and tried formula then modified by things like wheel diameter and coupling rod geometry. The second is a limit imposed by friction - in which only factors are weight on drivers and coefficient of friction. Since sand increases the friction coefficient then yes - it does increase tractive effort in situations where friction is the limitation.
Truly - the art of making a steam for freight duties is to find a balance where the only truthful limitation of the locomotive is the piston pressure, as when force applied by steam exceeds friction, locomotive starts to slip. Which is why steam locomotive engineering before times of computers was a form of practiced 'hunch magic'
Now do the tractive effort calcs for the kitson-still Steamdiesel engine. :P yes, steamdiesel.
Would be very interested to see the TE formula expanded into a mathematical model that could describe/predict how a locomotive and train will behave at different speeds. It should be possible to derive the optimum throttle and reverser settings if the model is detailed enough.
There are several ways to account for it at speed, from pg. 23 of Principles of Locomotive Operation and Control: T.F.=[(0.85P*s*d^2)/D]* speed factor. P= pressure in inches, D= diameter of drivers in inches, d= diameter of piston in inches, and s= stroke in inches. The speed factor is basically has to be derived to show the locomotives tractive effort changes at speed, and the book isn't super clear there on how to derive it. But pg. 24 shows a Baldwin table that calculated out various common tractive effort curves as speed changes.
@jacoblyman9441 I wonder how much of that is theoretical and how much of it is empirical. Wouldn't surprise me if the theory is actually very complicated but if you stick your locomotive on a test rig you can take readings.
@jacoblyman9441 it's not the change of road speed, it's a change in piston speed.
Very informative