Recently, I was watching the Amtrak train Empire Builder depart St. Paul, Minnesota. While it was waiting, the locomotives were making a hissing, popping sound. What is this?
Also, on my way to work, I pass by the old sand yard in St. Paul, near where the brewery, 3M, and the old Whirlpool plant were served. The tracks are owned by the UP, and they still hold stuff there. There’s one engine that puzzles me.
UP 8624 is a diesel – sorry, I don’t know enough to identify it better – but it has grilles level with the walkway, near the end of the long hood, and you can see straight through. There’s nothing between the grille on one side and the other. Is this normal? I could imagine this being an air intake, but I thought I would see something in the space, something needing to be cooled off.
the hissing and “poping” sounds are the main air res. psi safty valve venting air…and the spitter valve “spitting” moisture out of the brake system
csx engineer
I think #8624 is a former DRGW SD40T-2, what is also known as a tunnel motor. They were modified to draw air in from lower levels to better facilitate running on routes with lots of tunnels (SP also bought these units).
There is nothing between the grille but there is above it, fans and indeed are used for cooling. If you were to get closer and look up above the grilles you would see fans. Having grilles high up on the bodyside caused a problem where there were lots of tunnels as the heat being given off from the locomotives was being sucked back in because hot air rises. Having the grilles lower down meant cooler/cleaner air was drawn in and made for better locomotive performance.
The way he says “modified” may seem a little misleading, they were indeed built like that straight from the factory, but they were a “modified” SD40-2 design. (I thought he made it seem like they were an aftermarkert kinda thing.) Nothing against CopCarSS though, I just thought I’d clear that up!