Wednesday, 13 August 2014

Coupling and Connecting Rods

Coupling and Connecting Rods for my Yankee Tank

The basic shape of these rods was cut using my oversize patterns on a pantograph cutting machine by Malcolm Wright of Wrightscale. They were cut from solid nickel silver bar to which I added the detail; cotters, oil boxes and the front cover plates mostly by reference to photographs. The cross heads are castings obtained from LGM's lists though they have been much modified to resemble as far as is possible those of a HR Yankee Tank and to ensure that they slide in the slide bars without fouling the motion plate or the support mounted on the rear of the cylinders. The connecting rods fit inside the coupling rods so the omission of the covering plate on the big end of the former will not be noticeable.

The chassis runs well with the coupling and connecting rods in place but I've removed the inside valve gear as this is not running properly yet and needs attention. In fact you can hardly see it when the footplate is in place and I wonder if it's really worth the trouble.

I moved the pivot for the front bogie back 4mm and this seems to have improved cornering; the engine will now go round the curves on my test track, which I think are just under 6ft radius, without the bogie wheels catching on the cross heads, which of course shorts the works out.