Saturday, 7 June 2014

Yankee Tank chassis

Yankee Tank; structure of chassis


Only one of the original three turned brass 25.5mm frame spacers is still in place and this will be removed when the cylinder cross pieces, which slot into the frames, are soldered in place, these replace the turned spacers which can then be re-used. The third cross piece, behind the cylinders, is the motion plate, which extends beyond the frames to form the support for the rear of the slide-bars. The front steps are attached to the ends of this which makes it difficult to see what's going on in this area, though there is a 3/4 front photo of HR52 extant which helps clarify the shape of the support. The valve spindles are in place between the frames; these are part of the Martin Finney kit for the inside motion of his Adams Radial Tank which fit the Yankee Tank very nicely and which I hope to make work.

I'm using a 3-point suspension system based on the ideas illustrated in the late Geoff Holt's book "Locomotive Modelling", the suspension points being the rear fixed axle and the front bogie pivot point, the front driving axle moves in Slaters' brass  hornblocks in slots in the side frames. I was at the G0G show at Cleckheaton recently and discussed this method of suspension for a 4-4-0T with the man on the G0G Technical stand, Nigel Smith no less. He didn't think much of it and said that he prefered to compensate all four driving wheels, which he thought would give better hauling power. Well I've opted for Geoff's method now so we'll just have to wait and see.

The coupling and connecting rods are a project in their own right which is underway at the moment. Malcolm Wright of Wrightscale in Aboyne is machining a set of rods from a pair of oversized patterns that I made. These should enable me to get the engine up and  running soon.