[modeleng] Re: Slide valves
- From: "Phill Smith" <steam@xxxxxxxxxxxxxxxxxxxxxx>
- To: <modeleng@xxxxxxxxxxxxx>
- Date: Thu, 9 Apr 2009 23:33:03 +0800
Gent's,
It's the degree of superheat that is the problem. Many of the earlier
designs of superheaters were not much more than driers, and didn't have any
problems with slide valves. Once superheat temps went to 350°F and higher,
the lubrication problems started. Peter hit the nail on the head with the
complications of poor lubrication. Some slide valve engines survived and ran
sucessfully with high superheat after the 1930's due to the development of
high temp oils that could survive and lubricate at high superheat temp's.
600W was the first step up in the superheat lubrication, and what those of
us who have real working superheaters, should be using as we don't get high
enough temp's at the cylinder to warrent high temp superheat oil.
As a side note; saturated steam needs little or no lube oil for lubrication,
as the condenate acts as a lubricant. But with a small amount of lubricating
oil, the friction drops much lower. Adding more oil will not decrease it
further.
Cheers,
Phill.
----- Original Message -----
From: "Jesse Livingston" <fernj1@xxxxxxxxxxx>
To: <modeleng@xxxxxxxxxxxxx>
Sent: Wednesday, April 08, 2009 10:02 PM
Subject: [modeleng] Re: Slide valves
> Peter et al,
>
> The high pressure of superheated engines caused problems with the slide
> valves abrading their seats and wearing rapidly as well as making them
> hard
> to move which wore the valve linkage excessivly. Possibly the Pom poms,
> had
> balanced slide valves? If so that would have enabled the engines to
> operate
> with superheated steam - - - - I think. Well, it sounds like a good idea
> to
> me anyway!
>
> Jesse the Redneck machinist in Troy, TN
>
>
> ----- Original Message -----
> From: <peter.chadwick@xxxxxxxxxxx>
> To: <modeleng@xxxxxxxxxxxxx>
> Sent: Wednesday, April 08, 2009 4:14 AM
> Subject: [modeleng] Slide valves
>
>
>> In 12 inch to the foot gauge, it appears from the various writings that
>> slide valves were not too good with superheated steam. Why?
>> Just to complicate matters, a lot of the GC Pom poms had slide valves and
>> superheated steam,and they were not an unsuccesful design, especially
>> considering the longevity of the class.
>>
>> In the late 1950's, it was usually a Pom pom on the 4.50 from Retford to
>> Sheffield; not a very well patronised service from Retford to Worksop,
>> and
>> so it was good for clandestine meetings with the girls from the High
>> School. Strange how age gets you: I remember more of what the Pom pom s
>> looked like than the individual girls!
>>
>> Peter Chadwick, Swindon
>>
>>
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