Відео

All wheels can have it

@RailAcademy no .. only one wheel it is mounted...I saw

Please watch my video on coded track circuits, it explains impedance bond in detail

Interesting. Which country is it? I would love to hear more about it. If possible could you add a link to a web page that mentions that?

@@RailAcademy Poland. Find Tmechatronik or Tmechanik. Both are train engineers. First is more than train engineer. He is instructor and doing much more about safety. Knowledge level master and both of them like to share explanations.

Amazing. Just subscribed. I wish I understood polish though.

Thanks!

I agree. I did not know how shallow they were until I inspected them in person for the first time. I was like wait what these shallow flanges keep our trains on the rails?

Flange depth does not keep the wheel from derailing, it's the shape of the transition from the flange to the tire that does the work. When two rails intersect, such as is in a switch or crossing, a gap must be provided in each rail so that the flange of a passing wheel on one rail can move through the other rail. These gaps are intentionally made to match the flange depth. This supports the edge of the flange passing through the gap. The result is a smoother ride and less wear and tear on the rail on each side of the gap, because the wheel rolls through the gap on its flange.

I differ. A concept of increasing flange length to increase the flange climb distance limit was proposed by Wu and Elkins in AAR report R-931 in 1999, and further validated by Wilson et al in ASME International Mechanical Engineering Congress in 2004. They concluded that increasing flange length (which is the straight length after the transition) would increase flange climb distance appreciably. It is also intuitive that deeper the flange, the more the train will have to work to climb the rail.

@@RailAcademy I agree that it matters within the limits of the various cited references. I suggest that even the maximum flange depth, within those limits, will still appear to be "too shallow" to all but the most highly-trained eye. For many of us, our intuition about the role played by the flange is overly influenced by our experience with toy trains and model trains. A common and incorrect intuition is that a train is kept on the track by the flanges rubbing against the inside of each rail. As your well-documented piece details, the reality is that the curved surfaces of both the filet and the edge of the rail interact to use gravity to keep the wheels centered and on the track. Your table at 13:27 does not appear to reference the radius of the edge of the rail that interacts with the flange angle -- perhaps that's somehow factored into the "flange angle" metric. That radius of the inside edge of the rail is itself carefully engineered and maintained. At the extremes of displacement, the interaction between the flange and the rail creates the "flange squeal" most commonly heard on the tight turns of streetcar tracks. Any flange depth in excess of the above cited limits does not contribute to avoiding derailment.

I mean I agree. I've seen that video too, the trains can still survive that broken rail but there has been derailments because of hairline fractures.

I beg to differ: en.m.wikipedia.org/wiki/Eschede_train_disaster

Federal Railroad Administration (FRA) over here in US says more than 15% derailments happen due to broken rails and is the most leading cause. www.scientificamerican.com/article/broken-rails-are-leading-cause-of-train-derailments/

Haha up until I studied it in my masters I also thought it was something I didn't know I needed to know.

@@RailAcademy Best kind of learning imho

Yep sorry I hadn't figured out the best settings with mic and final cut pro until now

I beg to differ. Wheels always, and I mean ALWAYS, make sinusoidal motion. It is known via Klingel's formula (derived in 1883), which derives the equation for simple harmonic motion. The wavelength of the sinusoidal motion is = 2.pi.square root((wheel radius.track gauge)/(2.tread taper)). The reason you don't feel it is because it is damped. Hunting occurs when this wavelength is too short or frequency is too high, causing the ride to become uncomfortable and the unwanted oscillation to be too vigorous.

It's a dynamic system designed to self-correct, with no natural damping. It's oscillating. Most of the time though you barely notice it. Those "hunting oscillations" you mention are the same thing, happening for the same reason, except something has either petrurbed the system too much (sh!t track, for example), or whatever excites them enters resonance (that's where speed comes in). Just because you don't normally pay attention to them doesn't mean they're not happening though. Other oscillations you didn't know were happening: 1. Long-period longitudinal oscillation in a cruising aircraft. While it's "flying level", it's actually in a very slow cycle of climb and descent. It's called the phugoid oscillation, look it up. There isn't a statutory requirement for this particular oscillation to be stable, and as a result, on many aircraft (especially bigger ones) it is not. Left to its own devices, an aircraft with a sufficiently unstable phugoid will keep making bigger and bigger climbs and descents, until eventually it falls out of the sky (see 68-0218). Fortunately either some good automation or a well-trained neural network is usually in full control of the machine. 2. The spiral trajectory of a rifle bullet. An artifact of the dynamic stability behaviour of a spin-stabilised projectile, especially a high-speed one (with a long nose and boat tail) is a spiral path through the air. This is normally initiated by the harmonic motion of the barrel, which results in angular perturbation during barrel exit (the muzzle gives it a kick in some direction or another). Gyroscopic precession then converts the overturning moment into spiral motion, which continues for the duration of the flight, tending towards zero. Some designs however exhibit rather odd limit-cycle behaviour. The 168gn Sierra Match King, for instance, likes to sit at around 2° yaw. After launch, it will *rapidly* dampen its initial high yaw and settle into a 2° spiral. If there didn't happen to be any yaw, it exhibits an instability that will create it, and again it will settle into that 2° limit yaw. But to the regular competitor at the 100m range it looks like it went in a straight line from muzzle to paper. 3. Literally every bit of steel out there, if given a good knock. Again, all sorts of elasticity, and no damping. Sinusoidal oscillation is something you start noticing nearly everywhere after studying dynamic systems for a while. It's like the whole world wants to oscillate, and in 95% of cases you can model that extremely well as a spring-mass-damper system, like the suspension in your car.

My favorite comment <3

Yes, the wheel-set has a sinusoidal motion as it travels along the track due to the conical wheel profile. In a perfect mathematical world, you can argue that the left and right rolling radii shall be equal on straight or tangent tracks and no reason for hunting, but this is far from reality

haha yes, the rail will likely roll over (another topic I am making a video on).

Agree but I am guessing these instances happen because of complacency. When you do this 30 times everday for 365 days for 10-15 years, you start becoming complacent and want to save time so you start doing these things.

Glad it was helpful!

Glad it was helpful!

Always welcome

Can you clarify? I mentioned in the video that it will work on bidirectional tracks

Yes both, train on track or circuit broken or rail broken

Please check part 1 of the video

Glad it was helpful!

Glad you liked it

Apologies but i only use publicly available information to make videos. I would need product documents of these to make a video on specific products but i believe that information is proprietary.

Thanks for that!

Thanks for liking

Can you specify which graphic exactly?

​@@RailAcademy@9:45 for example. Nice video too.

Thanks for liking

Thanks a lot Boyd. Your comments are a great motivation for me.

Thank you, hopefully you're enjoying the content here.

@@RailAcademy Oh definately! We all have our teachers or idols no matter our level or specialty. Ever since this video I keep looking at a pair of rails now as antennas too. All your fault!

You are so welcome

@@RailAcademy I'm a railroad signal trainer, could I please use this video in my classes?

I dont think its a mistake. I do agree, Your definition is more detailed. But on a general note, headway just means distance and/or durations between two vehicles in transit.