[modeleng] Re: Steam loco configurations

Thanks for this reply Peter, but I seem to have missed an important point 
along the way. Are these pony trucks, or whatever the skeleton 2-wheel 
bogies are called, designed to be substantially load bearing or principally 
there to help keep the loco on the rails please? Is all of the loco's weight 
(excluding bogies of course) supposed to be carried by the main driving 
wheels for instance? If so, I can see how this would help with their 
traction! In my ignorance, I had always assumed that the bogies were there 
to prop each end of the loco up, silly as it now sounds ....

Tony.


----- Original Message ----- 
From: <peter.chadwick@xxxxxxxxxxx>
To: <modeleng@xxxxxxxxxxxxx>
Sent: Friday, August 31, 2007 8:41 AM
Subject: [modeleng] Re: Steam loco configurations


> >Another question however - on the 2-6-4's and 4-6-2's that I have been
> looking at, I cannot sort out how the skeleton 2-wheel bogey works. Is it
> just on a trailing arm, or is there a vertical rstraint as well please?<
> It depends. The GWR used a pony truck consisting of relatively thin bars,
> which had a tendency to bend easily. Gibson in his book is very critical -
> says it's like a set of pony reigns on a buggy that Abe Lincoln would have
> driven! He describes at some length the problems in Swindon works in
> straightening them out after
> even minor derailments on bad track. The trailing truck on the Gresley
> Pacifics, on the other hand, was a pretty substantial affair with Cartazzi
> axleboxes. These are on
> inclined plane slides such that as they move further across horizontally,
> the inclined plane offers and increasing returning force. I don't know
> what practice the LMS followed
> under Stanier. Webb, on the LNWR, went for radial axleboxes on his pony
> trucks. In all cases, there is some weight taken to the truck, the actual
> amount depending on the
> desired weight distribution, and to some extent, the settling of the
> springs.
>
> Peter Chadwick
> Swindon
>
>
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