Re: (TGR) L and M class Garratts

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

steam@1earth.net wrote in message <394fdcc5.10311592@news.1earth.net>...
>On Tue, 13 Jun 2000 21:39:23 +1000, "Derick Wuen"
><cullend@webone.com.au> wrote:
>
>>
>>steam@1earth.net wrote in message <394426fb.2535087@news.1earth.net>...
>>
>><SNIP>

>>(1) We are talking about the 3'6" gauge TGR in the early part of the 20th
>>century, not some super-railway built for speed and tonnage with adequate
to
>>unlimited shop resources, or some fuel-deficient country like France where
>>the fuel cost / labour cost tradeoff favoured more mechanical complexity.
A
>>4 cylinder Garratt makes sense in Tassie; a multi-cylinder inside
connected
>>anything is silly ...... errr....... overengineering.
>
>No it is not silly, Tasmania has to import coal, thus fuel efficency
>is an important factor. Also the valve gear is not that complex,
>mostly outside, with a simple lever to the inside cylinders. As there
>is no boiler above the valve gear, there is enough room for maintance.
>The M class was cutting edge technology for its day, unfortinately its
>use of radial axles was its downfall.


Just to put the record straight here, I am not complaining about
complications in the valve gear department... its straightforward. What I
object to is inside connected machinery..... in general its a pest, but on
3'6" gauge its silly..... 2 cylinders, 2 crossheads, 2 conrods, a cranked
axle, who knows how many oil resevoirs, all between the frames. And on a
Garratt there are 2 lots of this. To prepare the thing, as I said in a
previous post, would require a midget and a pit.

As for no boiler above the machinery, thats right.... there is a water tank
at one end and a bunker / tank combination at the other. Even more
restricted access. I have adjusted the brake linkage on a 60 class a couple
of times, with only a 60 foot pit to work from, and it was more constricted
than servicing inside valve gear conventional locos.

I guess this is where I depart company with Deeble and you, presuming Deeble
actually did order an 8 cylinder:

If I had to exercise judgements about fuel efficiency / savings vs. first
cost and maintenance of the 8 vs. 4 cylinder design on early 1900's TGR I
would have opted for simplicity. I think most of the reported efficiency
gains would be down to the generally excellent boilers on Garratts...
especially by comparison with 3'6" gauge conventional locos which had to
cram in driving wheels and boiler in the same vertical space.... certainly
in Sth Africa Garratts "blew away" similar sized Mallets, with boiler
proportions being a big factor in their comparitive success.

 >
>>(2) we are talking about one of the first "full size" Garratts here. They
>>didn't know much about the behaviour of steam delivery or exhaust
clearance
>>and drafting with a cylinder on each corner, let alone 4 in a row across
>>each end. At this point in engineering history, "conventional" 4 cylinder
>>layouts on standard gauge (let alone 3'6") were problematic (GWR/ de
>>Glehn..du Bousquet derivatives excepted).
>>
>>So either we have a stuff-up in specs, or reprehensible overengineering by
>>Deeble. You seem to be going for the latter.
>
>There is no evidence for the suff up in specs. Logical engineering
>yes. The result was a fast powerful locomotive, standardised  free
>steaming boiler with a light axle load and small out of balance
>forces. I cannot see what the problem is with ordering the best 3'6"
>passenger locomotive of its day. You get what you pay for.


The evidence for a stuff-up is only circumstantial, I concede. But I think
its compelling.... No other 8 cylinder Garratt; no 3'6" gauge inside
connected loco of any description on any Australian railway after the M.

Apart from all of that, I would dearly like to see/hear one in full-cry.

>>>Terry Flynn
>>>
>>>For up to date HO scale model railway standards go to
>>>http://www.freeyellow.com/members/trainstandards/index.html
>>>Includes extra finescale standards improved P87 and correct wagon weight
>>formulae.
>>
>>
>
>Terry Flynn
>
>For up to date HO scale model railway standards go to
>http://www.freeyellow.com/members/trainstandards/index.html
>Includes extra finescale standards improved P87 and correct wagon weight
formulae.