Articulateds

[nw-mailing-list at nwhs.org]

 >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