Why do train engineers hit the wheels/brakes with a metal rod?

Question

I feel like every time there’s a train in a movie, they show an engineer walking along the cars hitting each car’s undercarriage with a rod or hammer. I have also seen this in documentaries, so it’s not just Hollywood. What is the reason for this?

In: Other

Answer 1

I work in power plants and can attest to the trailing method. There are very large bolts (3″ diameter and larger) and the most simple and quick way to check if they are torqued properly is to tap em with a hammer. A nice ring is a torqued bolt. A flat sounds means it’s not tight enough.

Edit: the hammer should also bounce off. Kinda a feel thing to I guess.