GWR Siphon G & H Bogies

[81E]

As I have several of the old Airfix type Siphon s and H, I have been creating some variety by fitting alternative bogies. (GWR American and Plate Framed - see below) However, does anyone know if either (or both) these types of outside framed siphons were fitted with Churchward Fishbelly bogies?

 

 

Edited April 7, 2020 by 81E

[Miss Prism]

I don;t think any Gs or Hs were fitted with fishbelly bogies. Early ones were fitted with volutes

 

[Wickham Green too]

9' American, 9' volute, 7', 8'6'' or 9' pressed steel ..... according to the HMRS Siphon 'bible'.

[jim.snowdon]

And I don't think that the volute spring bogies lasted all that long.

 

Jim

[Wickham Green too]

The HMRS book isn't specific on that, just noting volutes as "Used under .... diagrams O.11 and O.12" - though 'American' bogies are also listed for those diagrams. The only photographic evidence is of No.1359 ( O.11 ), when new, and only two later changes are listed for this Lot ....... though, as they say, "with no change of wheelbase, there was no impelling reason to note a change of bogie". There are photos of "Siphon Bogies" later in the book but the volute example illustrated isn't under a Siphon.

[Miss Prism]

I get the impression the volute bogies were not a success. Where fitted initially under trailers, they were replaced quite quickly by Americans or fishbellies. If they were rough-riding, that's the last thing one wants under a bunch of milk churns.

 

[Wickham Green too]

Unless you want to make butter ...........

 

Slinn & Clarke do say that the actual volute springs were replaced with coils - but I guess that didn't cure the problem.

[jim.snowdon]

It probably didn't, and might even have made things worse. Without any other information, I suspect the problem may have been an almost complete absence of damping in either the primary or secondary suspension.  The potential result would have been instability in response to track irregularities, and vertical irregularities were wont to occur every 45' in the jointed track of the time. Normally, with leaf springs, there is a significant element of damping from the friction between the spring leaves.

 The GWR's American bogies (and the similar bogies used by a few other railways) are a hybrid, with coil springs on the primary suspension but leaf springs for the secondary. Given how long they lasted, the combination must have been adequate. The Commonwealth bogies used by BR had, as far as I can recall, coil springs throughout, and were equipped with vertical dampers in parallel with the secondary suspension.

Coil springs didn't really make it back into rolling stock suspensions until the arrival of the B4 bogie, which incorporated dampers from the beginning.

 

Jim

[wilwahabri]

Excuse me for butting in here, I have a question bout the wheel sizes used on the Siphon G bogies. I have a drawing of the 0.11 version which shows 9'bogie centres but no detail of the bogie or wheel size. Scaling from the drawing (a bad idea, I know) I get a wheel size of bout 3'9". I expected 3'6". could anyone advise me of the size of the wheels please?

 

 

[jim.snowdon]

3' 7 1/2" (nominal new), the de facto standard size across the British railways.

 

Jim

[Wickham Green too]

..... in round-ish figures ! : a quick trawl of drawings shows this figure for GWR & LMS coaches, 3'7'' for Southern and 3'6'' for Pullman and BR Mk1 ............................... though any difference is of little importance below, perhaps, Gauge 1.

[wilwahabri]

Thanks fr the input

 

[ikcdab]

So, which bogies do I need for the Lima siphon G?

Is it Bachmann 36-010

https://www.Bachmann.co.uk/product/collett-coach-bogies-(x2)/36-010

 

Or is there a better option?

 

Ian