Is an engine bumping into a string of coupled railroad cars on a track producing transverse or compressional waves?

Answer 1

An engine bumping into a string of coupled railroad cars on a track produces both compression and transverse waives.

The engine bumping into the cars creates compressional waves down the string of cars. These waves are taken up by the spring action of the Janney couplers.

The law of inertia can cause transverse waves in the coupling motion that can force railroad cars off the track.

Think of it this way.

If all cars in a cut weight about the same, as one car bumps into the other most of the force is passed down the string of cars.

If a empty car pushes into a loaded car too fast the empty car may not have the force to start the loaded car moving. All the force that the empty car has has to go somewhere. The only direction it can go is up or to the side derailing the empty car.

That's why there are restrictions on how fast cars can be coupled together. The spring action in the couplers in railroad terms is called slack.