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Drummond 4wh Coach Gas Tanks

Posted: Thu Jun 18, 2020 11:49 am
by JimG
I'm picking up on work I started nine years ago on models of the Drummond four wheelers. Back then I used the building of them to test out using a CNC milling machine to machine all the relief detail on styrene material. I now have to construct the underframes with as much detail as I can and gas tanks are an obvious addition. The two official GAs of the first and third I got from the NRM OPC archive only have Westinghouse brake details, but I note that a drawing of a third brake in Mike Williams' carriage book has what looks like two cylinders shown in feint dotted lines. Are these the gas tanks? And how were they placed across the underframe? I've taken an excerpt from the book to save having to search for it. ;)
CR-Coach-Gas-Tank-01.jpg (61.69 KiB) Viewed 1717 times
Also, how common were the twelve spoked wheels on these four wheelers? There is also a drawing of a full passenger brake a few pages on in the book which also has the twelve spoke wheel. But the drawings for the full first and full third show Mansell wheels.


Re: Drummond 4wh Coach Gas Tanks

Posted: Thu Jun 18, 2020 1:53 pm
by lindsay_g
Damn, in the absence of such info, I've modelled mine with one large tank offset to one side per the NBR equivalents (not finished - nothing new there then - so time to change). It does look like 2 tanks on that plan and presumably offset to the sides per the 6 wheel coaches.

nbr coach.jpg
nbr coach.jpg (117.31 KiB) Viewed 1708 times

Re: Drummond 4wh Coach Gas Tanks

Posted: Thu Jun 18, 2020 6:38 pm
by JimG

I was wondering if the drawing might be showing the position of alternate options for a gas tank. The other possibility is that there is a tank on each side of the underframe but, because of the Westinghouse gear attached to the inside of one of the soldebars, one tank has to be of smaller diameter.

Jim G.

Re: Drummond 4wh Coach Gas Tanks

Posted: Fri Jun 19, 2020 1:21 pm
I've just been looking at the original scan of the 4-wheel carriage that Jim showed earlier. There's a line of script just below the line of the metal strip tying the two axle guards together which reads "gas cylinders, fittings &c shown in blue." These are the feint lines referred to and is only a slight help on a monochrome scan! Close inspection suggests that there are indeed alternative gas cylinder types/positions. One is the long version modelled by Lindsay; the other comprises two, presumably diagonally opposed, short larger diameter cylnders. This looks to me like one of those occasions when you could model either, without it becoming a burning question sometime afterwards.

I can't explain the use of 12-spoke wheels at this stage in carriage evolution. These were the original style wheels with wrought iron spokes that were fitted, for example, to saloon 2A, which dates back almost to the start of the CR. Mansell wheels were in use from the early 1860s and the design came out of patent in 1878. (Carriage book pp.43-45)