Swapping piston valve for slide valve casting. Alco 2-6-0 to 4-6-0

[rogertra]

I have several 4-6-0s that unfortunately come only with slide valves instead of the more modern piston vales.

Before I order parts, or dismantle one each of the 4-6-0s and 2-6-0s to try the parts out,  can anyone tell me if the piston valve casting(s) from the Alco 2-6-0 will fit onto the the 4-6-0s?

[rogertra]

Thanks for the reply PF.

The vast majority of class one railroad's steam that survived into the 1950s had piston valves.  While the slide valve would be acceptable for a shortline, I feel that any class one 4-6-0s and even 4-4-0s that lasted into the 1950s would have had piston valves.

Of course, someone will come up with an exception but I don't model exceptions, I model the typical.  

[Johnson Bar Jeff]

The vast majority of class one railroad's steam that survived into the 1950s had piston valves.  While the slide valve would be acceptable for a shortline, I feel that any class one 4-6-0s and even 4-4-0s that lasted into the 1950s would have have piston valves.

I'm sure I read somewhere--but I don't remember where  --that the installation of superheaters in older locomotives also required a rebuild with piston valves. That certainly seems to have been the case with the famous PRR 4-4-0, #1223, which was built as a D16b class engine with no superheaterd and slide valves, then had a superheater added, making it a D16sb, and the valves changed to piston valves.

[rogertra]

[I'm sure I read somewhere--but I don't remember where  --that the installation of superheaters in older locomotives also required a rebuild with piston valves. That certainly seems to have been the case with the famous PRR 4-4-0, #1223, which was built as a D16b class engine with no superheaterd and slide valves, then had a superheater added, making it a D16sb, and the valves changed to piston valves.

Yes, it's my understanding that superheaters and slide valves just don't work together due the the dryness of superheated steam hence locomotives converted to superheating were also converted to piston valves, which are more efficient anyway.

I just wish that manufacturers who advertise steam locomotives as "modernised" would make sure the engines have piston valves and not slide valves.  A  locomotive with slide valves is hardly "modern".  Mr. B. please note. 

[ebtnut]

In steam railroading, "modernized" is a pretty broad term.  It can range from adding new/different applicances all the way up to "jack up the bell and put a new loco under it".  As for piston vs. slide valves, it is true that most main line roads sold, scrapped or rebuilt most of their slide valve locos to superheat and piston valves, especially into and following the Depression.  However, there were suppliers who offered a piston valve rebuilt kit that dropped onto the top of the cylinders, maintaining the appearance of the slide valves but allowing for superheaters to be iinstalled as well.  I believe one of the Ma and Pa 4-6-0's had this done.  And of course there were the exceptions to the rule, where some locos used for specific branch lines or other services weren't worth the expense of rebuilding and ran right to the end of steam.  The famous Wabash Moguls come to mind as a prime example. 

[Doneldon]

In steam railroading, "modernized" is a pretty broad term. 

That sure is the truth. Lots of shops rebuilt or replaced whole boilers, changed fuel, used larger or smaller wheels or redid the running gear. Heck, the Santa Fe built the giant 2-10-10-2s from two 2-10-2s, and then rebuilt them back to two 2-10-2s (in two different classes!) when it became obvious that they couldn't supply enough steam to run the "Double Santa Fe."
                                                                                           -- D

P.S. Have you ever seen three consecutive twos in a sentence before?

[Johnson Bar Jeff]

In steam railroading, "modernized" is a pretty broad term.  It can range from adding new/different applicances all the way up to "jack up the bell and put a new loco under it".

Put another way, some locomotives were like grandpa's ax that has had three new handles and two new heads.