Re: (TGR) L and M class Garratts

[John Duncan McCallum <mccallum@melbpc.org.au>]

Derick Wuen wrote:

Much snipped

> Do you know the crank settings on the M? If each crank was at 180 degrees to
> its inside mate (implied by simple rocking bar drive to inside valve gear)
> and the left and right machinery was at 90 degrees, imagine the noise!.....
> talk about boogie, eight beats to the bar! from each engine! now imagine a
> frosty winter's morning on Rhyndaston bank 1 in 40, with engines slipping in
> and out of synch!

I don't know if you're being facetious here, but a 4 cylinder engine
with inside
cranks at 180 degrees from its outside counterpart usually does not make
any more
noise than an equivalent 2 cylinder machine. There are, in fact, only
four exhaust
beats per revolution, as the inside and outside cylinders exhaust
simultaneously.
This is also because the cylinders on a four cylinder machine are
usually smaller
than those on a two cylinder machine of the same power.
The only four cylinder engines that I know of that had eight beats per
revolution
were the locos designed by Holden of (I think) the Northeastern Railway
in 
England. This was because he used a more complicated version of the
Gresley
conjugated gear, which required the cylinders to be set at roughly 45
degrees.

-- 
==========================================
John McCallum, member Melbourne PC User Group,
email <mccallum@melbpc.org.au>