Hello,
Any idea what was the purpose/function of the cylinders on the front of some steam locomotives as indicated below?Thanks in advance!
Yup.
The pictures show two cross-compound air compressors. They supply the air for the air brakes of the train.
They are usually mounted on the left side of the loco. In this case, though, they put them on the front of the smoke box. They were also sometimes placed on the front deck, kind of below where they are in the photos. And turned 90 degrees.
There are/were also NOT-cross compound air compressors. They look like half (split vertically) of the ones in the photo.
There could be one or two. And the GN used three, on occasion.
In the early days, the air compressor tended to go on the right side (instead of the left). Wonder why the change....
Ed
Possibly due to the size of the boiler and side clearance. I've only seen the front-mounted compressors on really big engines.
Chris van der Heide
My Algoma Central Railway Modeling Blog
Pumps mounted on the smoke box cover, as shown above, are often referred to as 'flying pumps'.
I have seen pumps mounted forward on the side of the smokebox. In this case, it was a Baldwin 90 ton 2-8-2T in Port Alberni, on Vancouver Island. It's a relatively small locomotive. In the image below, the copper cladding gives them away.
cv_acrPossibly due to the size of the boiler and side clearance.
The New York Central Niagara is a good example of that. There wasn't even enough room for the bell, which was tucked up behind the bell crank of the valve gear, turbo generator along side the frame behind the last driver and there wasn't much of a steam dome to speak of, just a perforated dry pipe at the inside-top of the 100-inch diameter boiler.
Regards, Ed
A few smaller locos have the pump in the front--Frisco 1630 has the air compressor on the pilot:
Sometimes pumps are covered by a shield to protect them from dirt and debris, like the venerable Mantua Pacific:
Gary
The explanations I have seen for mounting the air compressors on the front of the locomotive: side clearances, a desire to have a straight running board, and balance (since they are heavy things). Perhaps also easier access for working on them in the roundhouse? On the other hand they'd also seem to make entering and working on the inside of the smokebox more awkward.
Dave Nelson
In reality they are steam engines driving an air compressor. Some were compound which have one larger than the other that used the steam twice (compound) and others the same size. Some had insulation and cladding covering both engines. Early compressors had a single engine. As trains got bigger and pulled more cars compressors had to get larger. Also most maintenance equipment used large air cylinders like plows, flangers, Diffco dump cars and such which consumed massive amounts of compressed air.
Pete.
They also add front end weight which helps with weight distribution and tracking
Deleted.