Re: (TGR) L and M class Garratts

["Derick Wuen" <cullend@webone.com.au>]

Apologies if this turns up as a repost for others.... it has not appeared on
my newsserver, and sort-of covers some of Terry's post.

-----Original Message-----
From: Lambing Flat <bullack@cia.com.au>
Newsgroups: aus.rail,aus.rail.models
To: Derick Wuen <cullend@webone.com.au>
Date: Saturday, 03 June, 2000 10:29 PM
Subject: Re: (TGR) L and M class Garratts


>The replies to my original inquiry have been most interesting, and as I
don't
>have access to most of the reliable references mentioned, most illuminating
as
>well.  Derick has confirmed most of my own suspicions about the political
and
>operational issues surrounding their use on the TGR.  Thanks Derick!
>
>Derick Wuen wrote:
>
>> Deeble seemed very pleased with M and L classes after adjustments to
>> drafting arrangements and smokebox details. See "good press" coverage
from
>> Launceston Examiner of 30/11/1912, reproduced in "Beyer, Peacock
Locomotive
>> Builders to the World", Hills and Patrick, page 147. In summary, pulled
>> double the weight trains for only 25% increase in fuel.
>>
>> The (first) Campania disaster in 1916 involving the M was blamed on "fast
>> speeding" officially, but conspiracy theorists blame the track, based on
the
>> poor condition of the rail on the outside of the curve and the fact that
the
>> rear engine seems to have derailed first.
>
>Blaming the poor worker at the coalface (particularly a deceased one) has
>traditionally been the reaction of railway (and other) organisations caught
out
>by poor management practices.  Considering the size and weight of the
previous
>TGR locos I think it more than likely that the track maintenance practices
had
>not adapted to the new machines.
>
>> I favour the stuff-up over the conspiracy as an explanantion for most
>> unsatisfactory things. Thus looking at an 8 cylinder express loco design
for
>> a 1067mm gauge railway built to, well, err light standards smacks of a
>> stuff-up to me. Remember, the M and L were amongst the very first
Garratts
>> built, and communications had every chance of being garbled between
Tassie
>> and Manchester..... easy to misinterpret an order involving 4 cylinders
per
>> engine as being 4 cylinders for each engine unit as opposed to 4
cylinders
>> per each locomotive?
>
>I must say that I think that Beyer Peacock building an 8 cylinder machine
when
>the TGR actually wanted a 4 cylinder one most unlikely!  Multi cylindered
locos
>were all the rage on the top English railways at the time

To push the point further, another good reason for BP to "misinterpret" the
order.

Even in 1912, inside connected narrow gauge machinery was a known
operational minus.

and I suspect that Mr
>Deeble just wished to build the best and most up to date loco possible.  It
>wouldn't be the first time that an ambitious designer exceeded the
technological
>limits of his time!
>
>> I think the same result could be achieved with less machinery and
>> preparation time with a 4 cylinder locomotive which would have ridden
almost
>> as smoothly as far as the crews were concerned. Smooth riding is another
>> plus for the Garratt design, and no need for more naturally balanced 8
>> cylinders.


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!

Seriously, at the early stage of Garratt development, one of the concerns
was the impact of the long exhaust pipes from front and rear engines on the
steaming qualities of the boiler and back pressure on the valves.

Good exhaust performance on 4 cylinder engines was an issue, without the
complications of long pipe runs and flexible joints.

In the bunch of UK 4 cylinder 4-6-0's sort-of contemporaneous with the M,
the drafting impacts were often a problem (not on GWR who pinched design
details from du Bousquet / de Glehn French designs of some maturity)...
pulled fires, high back-pressures, and in one infamous (Irish) case the
double chimney applied actually sucked in air as the cylinders at 0 and 90
degrees exhausted up the front hole, whilst the cylinders at 180 and 270
degrees exhausted up the rear hole!

>
>But since the Garratt was a brand new type and its possibilities had yet to
be
>explored, and conventional wisdom at the time was that a multi cylindered
loco
>was smoother in running and easier on the track, then it is extremely
logical
>for the first passenger Garratt to be multi cylindered.  After all, it was
not
>universally accepted in Britain that a two cylindered loco could be as
powerful
>and as smooth running as a multi cylindered loco until well after WW2.


The smoothness of Garratts to those riding in cabs derives in large part
from their design as a vehicle. A bogie coach is smoother than a four wheel
coach because the bogie coach body is more remote from angular accelerations
of the bogies. Roughness, vibrations and dynamic augment are not transmitted
in large part from engine units to boiler unit in a Garratt. The machinery
still has to be balanced to minimise track impacts.

>
>> References (Durrant, Cooley) put down "failure" to speed; I think the M's
>> were just too sophisticated, through miscommunication of design specs,
for
>> requirements and track infrastucture, and the L's reputation suffered by
>> contagion following Campania.
>
>I think that this is definitely the most logical conclusion possible, given
the
>known facts.  I think that the "failure" of the M class Garratts had
>ramifications well beyond Tasmania though, since as far as I know, no one
else,
>save perhaps the Algerians, tried to build a true passenger Garratt again.


There were successful passenger Garratts besides the Algerian.... Brazil and
Spain had large elegant broad gauge express Garratts which performed well
for many years.

>> One wonders what might have been if an M had been let loose on some of
the
>> heavily engineered 1067mm railways such as in South Africa or modern day
>> Queensland.
>
>Or if development of true passenger Garratts had continued.  What a machine
the
>AC 38 might have been!
>

There was also a design study by BP for the VR for a double pacific Garratt
to cut out double heading of A2's on the Overland. Even when R's replaced
A2's, more often than not the Overland required lengthy assistant engine
mileage.
>
>DPC James McInerney
>
>STOP!  In The Name Of The Lore!
>
>At http://www.cia.com.au/bullack/ , "Lambing Flat's" mainpage for the HO
model
>and NSWGR information.
>Or http://www.cia.com.au/bullack/rvrtitle.html  for the "Rurr Valley
Railway",
>my G gauge garden line
>
>
>