Re: (TGR) L and M class Garratts

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

steam@1earth.net wrote in message <394426fb.2535087@news.1earth.net>...

<SNIP>

>A 4 cylinder locomotive would not be as fuel efficent or powerful as a
>comparable sized 8 cylinder garrat. Also a garrat has a lighter axle
>load and greater traction compared to a similar non articulated
>locomotive. The downside is higher inital cost and higher maintance
>costs for the garrat. The later is the reason simple designs were
>chosen.
>
>My view is  a sutiably designed standard gauge  8 cylinder garrat,
>with modern suspension would easily exceed the world steam train speed
>record, and woul be capable of hauling a greater load.
>


All of the above is cetainly arguable, including the bit I snipped about
better balancing.

But really......

(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.

(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.

>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.