4-8-0 M-2 class

[nw-mailing-list at nwhs.org]

Gordon:

A more accurate terminology, I¹d think.  ³Relief² valve has always puzzled
me a little, though I guess I could make up some reasoning for the term.

Pete Groom

On 7/17/04 7:57 PM, "nw-mailing-list at nwhs.org" <nw-mailing-list at nwhs.org>
wrote:

> Pete,
>  
> I likewise expected experts to expound on the esoterics of M2 "relief" valves,
> but I think that you covered the bases just fine.  One added comment: a check
> of drawings in our archives covering the M2 and other classes of N&W
> locomotives shows that the N&W used the terminology, "bypass valve" instead of
> "relief valve."
>  
> Gordon Hamilton
>>  
>> ----- Original Message -----
>>  
>> From:  nw-mailing-list at nwhs.org
>>  
>> To: N&W Mailing List <mailto:nw-mailing-list at nwhs.org>
>>  
>> Sent: Monday, July 12, 2004 4:20 PM
>>  
>> Subject: Re: 4-8-0 M-2 class
>>  
>> 
>> A number of  RRs used that type of relief valve – ATSF’s newer power comes to
>> mind.
>> 
>> I believe that relief valves relieved pressure buildup in the  cylinders when
>> the loco was coasting and the valve gear was “hooked up” so  that steam
>> couldn’t move from one end of the cylinder to the other.   (They may also
>> have helped to keep cinders, etc., from being sucked into  the cylinders
>> while coasting.)  Without them, I believe that engineers  had to keep the
>> throttle cracked a little so that the loco was working very  lightly, even
>> though the train may have been braking.
>> 
>> I chimed in  because no one else had; I’m sure that others have more
>> definitive  comments.
>> 
>> Pete Groom
>> 
>> On 7/11/04 7:33 PM,  "nw-mailing-list at nwhs.org" <nw-mailing-list at nwhs.org>
>> wrote:
>> 
>>  
>>>  
>>>> Hi,
>>>>  I have a question about the cylinders  on some 4-8-0 M-2 class locos, the
>>>> 1150-1160 numbers. On the cylinders of  some, there is a protrusion off the
>>>> side of the middle of the cylinder,  with square ends.
>>>>  . . .
>>> Sorry Tony, 
>>> They are pressure  relief valves.
>>> . . . 
>>> 
>>> Mark Lindsey
>>>  
>>> 
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>> 
>>  
>> 
>>  
>> 
>>  
>> 
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