Articulateds

[nw-mailing-list at nwhs.org]

The front and back engines both share a common trait. The main  
connecting rod would exert a varying amount of power due to the angle  
in relation to the vertical axle centerline.  Both simple and  
compound engines would go in and out of sync.  from watching lots of   
old A and Y class engines it seems the simples would sync up with  
both siderods at the same angle, while the y's in compound would tend  
to have one with the driver connected end down while the other would  
be up.

Mark Lindsey

On Aug 3, 2005, at 7:48 PM, nw-mailing-list at nwhs.org wrote:


> >From an engineering stand point, an articulated, compound engine  

> would

> send a set of pulses of higher pressure steam downstream to the low

> pressure cylinders 2 per revolution per cylinder.

>

> A straight articulated like a Class A would pull steam to the  

> cylinders

> from a common high pressure source (the steam dome) with all four

> cylinders essentially connected in parallel.  The only way to  

> influence

> the neighboring cylinders would be from the pressure waves reflected

> back up the steam pipes from the opening and closing of the cylinder

> valves.  These waves would be a function of the steam density, pipe

> size, resonant frequencies of the piping system, pile lengths and  

> valve

> opening and closing speed.

>

> Unless the drivers are slipping, one motor would tend to stay at the

> track speed it was running at.  If the two motors have different  

> driver

> diameters, they would move into and out of phase with each other.

>

> (Question, over time what do the driver diameters change to from a

> common starting diameter.  Do they all wear at the same rate so that

> the worn diameters are all equal at any given time?  Or do they  

> wear at

> different rates forcing the drivers into different diameters?  We  

> aren't

> talking major differences here!)

>

> G Rolih Cincinnati

>

>

>

> -----Original Message-----

> Sent: Monday, August 01, 2005 11:35 PM

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

> Subject: Articulateds

>

> N&W Veterans,

>

> I've read in a book "How Locomotives Work" that an articulated

> locomotive

> has a tendency to 'work itself' INTO a syncopation of sort where both

> engines that are 'out of phase' (perhaps due to a slip) with each  

> other

> will naturally seek to creep back into some form of natural rhythm  

> with

> each other.

>

> Personal experiences ??

>

>

> Thanks,

> Dave Willis.

> N&W steam lives on in Indiana

>

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Mark Lindsey
y3a at earthlink.net