Lady Kitty

by LBSC

A G.W. Consolidation Under Way

The engine is a sort of compromise between the 4700 mixed traffic class and the 2800 class mineral engines with small wheels. It has a bigger boiler and cylinders than either of them, and wheels which would be equal to 5ft.3ins., enabling her to pull a bigger load than the 4700's, and run faster than the mineral type. The cylinders are 7/8 th-in. by 1¼ ins. with ports something like "Fayette's" and valves actuated by Stephenson link motion between the frames. The driving axle is a species of eccentric exhibition, there are only five on it as there is only one pump 11/32 nd-in. bore and 3/8 th-in. stroke. The guide bar brackets will be outside and each attached to one of the running board supports. Contrary to G.W. practice, the coupling-rods are heavy and fluted, to give the desired "massiveness", and the connecting-rod is also oversize. In order to keep the centre lines of motion horizontal and parallel, the eccentrics have a much bigger throw than the valve travel requires, the inside pendulum lever, dropping nearly to axle level, and the inside pair being shortened sufficiently to get the correct movement of the valve spindles.

The "No. 19" Boiler.

I call it so because it is a combination of No. 12 and No. 7 in the Swindon classification. The smokebox and chimney are as on the King class, but the barrel has a hump instead of an even taper, the safety valve being set on the highest point. I found on previous G.W. engines I have built that, owing to the valve being set on the barrel and close to the water level, there was a tendency to prime when blowing off. This boiler barrel was intended to minimise the trouble, yet retain the G.W. flavour; so the taper extends from the smokebox to the valve, which is perched on the highest point, and from there to the firebox the taper is in the reverse direction. It is not very apparent in the picture, but the effect in the actual engine is quite good and adds to the general "massiveness". As the firebox cannot be very deep on account of the trailing axle, the foundation ring rests on the frames and the grate is the full width between, less thickness of plates. This arrangement, combined with a box 4½ ins. long inside, will provide ample steam for the big cylinders — providing, of course, that admission and cut-off are correct — without undue forcing. All the usual fittings and top works will be provided; the cab will be of the older pattern with short roof and no side windows, to facilitate handling, and a latest Swindon type high-sided tender is also in hand.

The constructional series appeared in The Model Engineer issues for 6th, 13th and 20th June, 1929.
The Association can supply photocopies of the constructional series to members.

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