External reducing valves

Mon Feb 11 13:30:22 EST 2019

Bud 

   Thanks very much . About to get my slow head around this . What you are calling the External reducing valve (relocated from the HP steam saddle and to above the right HP cylinder) is the same as the booster valve(same valve to allow HP steam to the LP cylinders)   ??     They eliminated what was called the emergency exhaust valve (inside the steam saddle)  made the intercepting valve positively controlled and added the external reducing valve is this correct thinking??  You have the internal valves in the saddle and the external reducing valve and not a third valve??

God help me I know I wearing you guys out

Larry Evans

From: NW-Mailing-List [mailto:nw-mailing-list-bounces at nwhs.org] On Behalf Of NW Mailing List
Sent: Monday, February 11, 2019 11:55 AM
To: NW Mailing List <nw-mailing-list at nwhs.org>
Cc: NW Mailing List <nw-mailing-list at nwhs.org>
Subject: Re: External reducing valves

I will add the date to Ed’s comment and answer Larry’s question about what the modifications included.

The Y6b 2197 was used to perfect the new system in the fall of 1952.  Beginning in January 1953, the remaining Y6b’s began receiving these devices first and then the 70 Y5, Y6 and Y6a engines got the changes after that.  This changeover was completed during late summer 1955.

Here is what the locomotives got with this modification:

Positively controlled intercepting valve (was not automatic since the engineer controlled this)

External reducing valve (relocated from the HP steam saddle and to above the right HP cylinder)

Booster operating valve (allowing the engineer to add steam to the LP engine when in compound at lower speeds)

About 13 tons of lead added to the LP engine (added adhesion to that engine for simple starts and running with the “booster valve” on)

Changing the valve events and timing on the Y5, Y6 and Y6a classes to that of the Y6b’s (the Y6b were built with the new valve travel)

As Ed said, all 100 modern Y’s were equal in capacity after this modification.  During this modification, the Y5/Y6 and Improved Y5/Y6 were listed separately in the ETT for tonnage ratings; after all 100 were modified the distinction between the improved and unimproved was dropped.

Bud Jeffries

From: NW Mailing List via NW-Mailing-List 

Sent: Monday, February 11, 2019 8:17 AM

To: NW Mailing List 

Cc: NW Mailing List 

Subject: Re: External reducing valves

A slight quibble on wording.  If "simple" is defined as all four cylinders exhausting to the atmosphere, then a compound locomotive actually starts in a modified form of "compound."  When starting, the front LP cylinders get a shot of high pressure steam through the reducing valve in the rear cylinder saddle.  The rear HP cylinders exhaust into the receiver pipe, not the atmosphere.  When the receiver pressure reaches some preassigned amount, the valve shuts off the direct live steam supply to the LP cylinders and the receiver pipe gets its supply solely from the rear HP cylinders.  As a result, the locomotive can start in "compound" with the HP cylinders exhausting to the receiver pipe, or in "simple" with all four cylinders exhausting to the atmosphere.  Other than that detail, Ed's explanation is correct.

Dave Stephenson

On Monday, February 11, 2019, 6:38:25 AM EST, NW Mailing List <nw-mailing-list at nwhs.org <mailto:nw-mailing-list at nwhs.org> > wrote: 

Larry - 

You have a few things confused here.  Alco developed an intercepting valve about 1910 for Mallet locomotives which automatically started the locomotive out in simple operation – in other words, live steam from the throttle into all four cylinders.  In order for this steam at high pressure not to cause the front engine to slip because of the larger cylinders, a reducing valve was incorporated to limit the pressure of this steam going to the bigger low-pressure cylinders so the front engine wouldn’t be slippery.  All N&W’s Alco Mallets had this feature and it was adopted as the standard for all the Mallets built by Roanoke.  Starting out in simple was automatic.  Also provided was a so-called “emergency” valve which could be operated by the engineer to keep the intercepting valve from functioning – in other words, to keep the engine operating in simple cycle until a difficult situation could be dealt with.  This is not the same as the emergency valve incorporated into the air brake valve.

When the improved intercepting valve was developed (in the early 1950s, I believe – someone correct me if I’m wrong) an external reducing valve was used which appeared as a cylindrical gadget above the right high-pressure valve chest.  When this was done, control of the simpling function was no longer automatic but was given to the engineer in the form of a lever in the cab that he could use as conditions required.  But simpling still required the use of the reducing valve.

The so-called “booster” valve which added a measured amount of throttle steam to the receiver to increase the power of the low-pressure engine was a separate valve under the control of the engineer so as to increase the power of the low-pressure engine after the engine had been changed from simple at starting and low speed to give the engine a bit more power under difficult circumstances.  All the 2100-series Y’s got this feature.  None of the earlier ones did, nor did the Z’s.  As these features were developed, all the 2100s were retrofitted so that N&W had 100 locomotives of equal capability.  If you had the 2101 out on the side of the mountain with tonnage, you would not be any better off with the 2200.

These features made N&W’s 2100-series Mallets far and away more powerful than anyone else’s Mallets.  The Y-2 of 1918 pointed the way, and the USRA Y-3s and descendents were far and away faster than all the others.  When you consider that the horsepower curve of a Virginian AE 2-10-10-2 peaked out at 8 MPH and that of a Y-6 peaked out about 30 (at 5500 DBHP) you can see why N&W took the trouble to keep on developing the Y engines.  I know, the AE had ten thousand pounds more starting tractive effort than the 2100, but that figure was good for bragging rights and that was about all.

Hope this helps and is not tMI.

Ed King

From: NW Mailing List 

Sent: Sunday, February 10, 2019 8:29 PM

To: nw-mailing-list at nwhs.org <mailto:nw-mailing-list at nwhs.org>  

Subject: External reducing valves

N&W in early fifty’s started using the external reducing valves on the Y classes. Which enable them also to manually to control the intercepting valve and

put superheated steam into the LP receiver  While running it compound.  Anyone have an idea exactly  what locomotives actual got this modification? 

All Y6bs ??  I know some Y5s.   I have heard all Y6bs but at this late date seems to me to be improbable?  Thanks for any help.      

Thanks

Larry Evans

Kenova WV

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