I’ve googled it but just can’t seem to grasp it. How do they stay on as well as they do at such high speeds, with so few incidents of crashing or derailing? Especially when anything could be lying across the track waiting to get lodged in the wheels.
I hear so often that trains are so safe, but I don’t think I can get over my anxiety with them until I understand *why* they’re safe.
In: 29
They are extremely heavy. And the wheel rims are flanged to prevent them from slipping out/off the rails, but the parts that rest on the rails are also conical which keeps the train centered between the two rails ([and is also the reason why they can go around curves without having differentials on their axels](https://www.youtube.com/watch?v=y7h4OtFDnYE)).
So basically to derail a train you have to put something across the tracks that the weight of the train/its very hard steel wheels can’t cut through, that will retain enough of its shape when the weight of the engine comes across it – basically need a giant chunk of metal or maybe concrete that is capable of lifting the weight of the engine up and off the rails.. or large enough that its mass and inertia is equal to the train. Or such that it is wedge shaped and can get down and under the front of the engine and not just get pushed ahead of it. That type of obstruction just doesn’t “fall onto the tracks” very often.
Most of the time when a train hits a truck or a car, the truck is just flung aside or split into two parts that are pushed aside. Very rarely does the train derail. Its only when something gets crushed and the trail rolls up and over it does it derail.
Having said that, it still happens. The Amtrack that derailed in Missouri – it hit a (full) dump truck. Of all the types of trucks to hit, yep a dump truck full of rock; that obviously was sufficient to be that unbreaking immovable chunk of metal. In this case dislodge the engine from the rails off to one side. After that, the engine is sooo heavy it just pulls the cars over a bit like how a truck trailer can yank the cab over when it takes an offramp too fast.
Dumptruck full of rock? 25 to 40,000 lbs. A Genesis P42DC (the engine of that Amtrack)? 268,000 lbs. Yeah, enough to shove it to the side just enough.
the wheel has a flange, meaning the inner part is considerably larger than the outside, this basically means it’s almost impossible for the wheel to go over the track as the flange prevents it from going over the rails unless something goes really wrong
the wheels aren’t meant to scrape the flange against the tracks, so ideally the wheels are made to self center and the flange is extra safety, but occasionally they do scrape, this is the noise you sometimes can hear going around tight corners
Trains are very heavy, so gravity holds them onto the track. They can’t slide off the track because the wheels have flanges which hold them on, and they can’t bounce out because the train is too heavy. They have to hit something very heavy to push the wheels out of the tracks.
The bit where they might be at risk of derailing would be on a bend, which is why the bendier your track is the slower you go (just like in a car)
They stay on the tracks because there is a flange on the inner side os the tacks that stop them from sliding off.
Train tracks are very smooth so the trains will be in contact with the track all the time. Curve radiuses are very large and there strict speed limitations you need to keep. The tracks are alos often not flat in a curve bit build with a slight incline to the train tilt inwards.
Train is very hthe eavy and wheels are solid steels. If you look at locomotives they tend to have something in the front that looks a bit like a snow plow or just a large piece of metal that extends down quite close to the rails that is there to stop stuff from getting under the train. There is also not a lot of stuff that ends up on track.
Even if there is a truck on a railway crossing it will weigh less then the train and the result a truck that breaks apart or is pushed into of the train. You can compare a car vs truck collision with a truck vs train. Small locomotives are in the 80 tonnes range and large in the 200 tonnes. Passenger cars are around 40 tonnes. Quite short freight cars for material like ore can be 100 tonnes loaded each.
The wheels are shaped with a slight angle that forces the train to ride in the center of the rails, the rails are spaced and secured in a multitude of ways that make it extremely difficult to come off the rails. It works
Train wheels aren’t disks with a flat rim. They’re shaped more like a slice off the bottom of a cone (pointing to the inside of the track), so they curve in. The train’s very considerable weight then causes the wheel to sit in the lowest point in the middle. Moving to the left or right would cause the train to slightly lift, which it’s weight counteracts. This keeps the train in the middle of the track. There is also a flanged edge on the outsides of the wheel, which would have to skip off the track completely for the whole train to come off the track. Lifting a train that high is very difficult, and would take a significant impact to do.
The left and right pairs of wheels are also directly connected with a bar, so the wheels must turn together instead of being able to turn independently. When the tracks makes a corner, the outside rail is longer than the inside rail so the outside wheel runs higher on the wider part of the cone and the inside wheel runs lower on the smaller side of the cone. The tightness of the turns in a track are always wide enough that as the outside wheel rides up on the track, it’s flange doesn’t need to hit the side of the rail.
This is a video on how train wheels stay on tracks
Trains’ wheels are slightly cone shaped, so that they are always aiming toward the middle of the track. They each have a lip inside, too, so the tracks act like bumpers on a bowling lane.
The design of the wheels is really cool. Check out this video .
Can I provide a bit of video evidence? Here’s a small passenger train (only three cars) that flings a semi and its loaded trailer off the track with ease.
The passengers felt a lurch, and one of the windows was damaged. The worst injury was a passenger that suffered facial lacerations.
[https://www.youtube.com/watch?v=1RNVBndJiSs](https://www.youtube.com/watch?v=1RNVBndJiSs)
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