Was reading a book recently that featured a photo of a Chicago & Northwestern steam locomotive with angled cylinders very similar to the one featured below:




What's the advantage of this over the more traditional cylinder placement? And if there is an advantage, why did this angled variant not become commonplace?

Also, what type of valve gear would this arrangement require? From the photos I've seen for engines of this class, I couldn't tell if it was Stephenson or something more unique.

This style of arrangement was referred to as "inboard pistons". They brought the steam chest closer to the frame making it easier to connect to the valve gear which was usually Stephenson's from what I've seen. I don't imagine it caught on as it was difficult to access and a maintenance headache as you can imagine. There are a few engines still extant with this type of cylinder.

Jason

The valve gear was operated by eccentrics on the axles not on the crankpins, thus the cylinder casting for piston valve engines (like this one) had to have the cylinders canted to allow the valve motion to connect.

Slide valve engines with inside valve gear were done differently.

There's a bit more to it than that.

As Lincoln Penn notes, most American slide-valve engines from 'time immemorial' did the valves differently -- they used a bell-crank arrangement to move the motion outboard to where valves positioned neatly over cylinders (for ease of maintenance) were possible.

That is the position where 'universal' piston-valve conversion chests are found.

In my opinion the 'inboard' chests are predominantly a way of positioning the valves to where the exhaust tract length and complexity is minimized, with the presumption that maintenance of piston valves in this location would be cost-effective (while slide valves would, in this country, almost certainly not be). There is also better mechanical integrity and avoidance of lost motion with more direct drive to the valves. I suspect that most locomotives built with these canted cylinders do not have the typical 'ancient' 4-4-0 feature where the frame can be separated midway for easier maintenance (that would make some operations, for example working on the rear of the cylinders, somewhat easier).

This is right about the time of the big switch to outside radial valve gears, which of course firmly established valve cylinder location slightly outboard of 'power' cylinders for geometric reasons. IIRC some classes of PRR Atlantics have the canted cylinders while others retain the bell-crank arrangement -- who has their copy of Pennsy Power I on hand to check?

I am very familiar with this locomotive as I used to operate it frequently while in operation in Wisconsin. The 1385 had Stephenson Valve gear. The motion from the inside gear went inside the frame to a point behind the cylinders, it was connected to a rocker box attached to the frame, and the other end of that rocker box then connected to the valve stem, going into the valve chest, the rocker box just stepped the valve gear over to the valve chest bore, and transferred the motion from inside the frame to the outside.

The Soo Line 2645 which is at the same museum as the 1385, also has the slanted cylinders. I do not have a picture of it to post..

sooline1003engr -

The "lately discovered" Soo Line 2-8-0 up in Columbus, North Dakota (#2412) also has these slanted cylinders. I don't believe any of the other 20 surviving Soo Line steamers have them.

Les

Soo Line 2645 (Brooks, 1900) at Mid-Continent also has them:

http://www.midcontinent.org/collectn/steam/soo2645.html

Both these locomotives are former Wisconsin Central power; the WC was big on Brooks power at the time, and Brooks was big on inside piston valves. The WC Atlantics likewise had inside piston valves.

And, the Soo proper had a class of light Pacifics built by Schenectady in the first decade of the twentieth cntury that had inside piston valves:

http://www.railarchive.net/randomsteam/ ... soo721.jpg

Unfortunately, none were saved.