Help with identifying these

[tightyfist]

Hi All,
A little help regarding features found on the hoods of some modern diesel locomotives. We can't determine if these fixtures are railroad specific or by manufacturer as an option.
The argument is over the function of these. I say they are sandbox sight glasses, located directly below the filler hatch and about 5/6 of the way up the box. My friend says they are lighted and are class/marker lights. I found an image that shows the glass illuminated, so I'm not entirely sure I'm right.
Anyone out there can clarify this for myself and friend ?
Cheers,
TF

View attachment 122184

 

[K-dub]

tightyfist, Welcome to RRF!

Your friend got you on this one. We called them Class lights and they're referred to as Marker lights some places as well.

They were illuminated by a bulb and had several different colored lenses that could be flipped into position inside the cab. The different colors indicated the train's classification/superiority. They were used before the advent of RR radio communications and were already phased out of use on my home Class I RR when I started 35 years ago.

They're still in place on lots of older units but most are deactivated.

 

[UP Scott]

Welcome Tightyfirst! As K-dub said, they're class lights and are not used anymore. I like the idea of a sight glass though, good guess...
Later...

 

[tightyfist]

Gentlemen,
My thanks for your input. I guess I'' have to bow to his superior knowledge base.
I was kind of hoping it was a lamp in the top of the tank on the picture I saw.
Until the next contest.
TF