Question for the locomotive engineers in the audience (come oooon, I know you’re out there!):
When you see a train idle on the tracks, you hear a clicking noise – sounds electric, like the noise that you get when you click two ends of jumper cables together when they are hooked up to a battery (don’t make a habit of doing this). It’s an irregular pattern, though, with erratic delays and speedups in the frequency.
What is this noise?
That’s probably the idling sound of a diesel engine. What you’re hearing are the lifters, a part that “lifts” the cylinder in the combustion chamber. At lower speeds, the lifters tend to fully extend, sometimes coming to a complete travel and making a “pinging” noise. At higher speeds, they don’t travel as far. Newer locomotives almost never exhibit this behavior.
It could also be the constant cycling of the hydraulic brakes – depending on the model of the locomotive.
I really don’t know what the sound is, but mentioning jumper cables in conjunction with traintracks reminded me of this tidbit of goofily earned knowledge–that if you bridge the two tracks with jumper cables near a railroad crossing, it will set off the lights & mechanical arm.
i grew up in the middle of nowhere. we didn’t have cable. we had to make our own fun.
You know train engines use their diesel engines to generate electricity, then drive the wheels with electric motors, right? If you hear something that sounds like an electric arc, it doesn’t seem unlikely it’s caused by electricity, although I don’t have any guesses what the mechanism would be.
I love the fact that someone asked this question on a blog, and even more that somebody actually answered.
When we quit being curious, we pretty much die..not enough curiousity in the blog-a-teria. We all already know everything.
Hi Chris, I asked a conductor who was sitting in one of the trains by the Cummins Station lower parking lot and got your answer - it’s the air brakes releasing the air via the valves… has nothing to do with electricity, pistons or valves!
Cool! I guess I could have asked the guys that drive the nashville star, huh?
Thanks!
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Chris, I’ve wondered the same thing… since I park in the Cummins Station lower lot, I’ll ask next time I see a locomotive engineer… or we could Google the question!