Sunday, 29 April 2012

200HP Pre-War Sentinel Locos (2)

The 1920s were not well known for mass production and, of its type, Sentinel 7109 was the first of not very many, only 14 in total. 7109 was actually a basic design around which variants and enhancements could be made to suit particular customer's requirements.

Two 200HP design variants were made to suit the Somerset & Dorset at Radstock where a low bridge required reduced maximum height. These were the Radstock Sentinels with their lowered cab roofs.

another pair of 200HP specials, with works' numbers 8147, 8148, was delivered in 1929 to the LNER. Eventually designated as Y10s, they were specifically intended for use on the Wisbech and Upwell Tramway.

On these, a second, front-mounted cab was added to make them capable of being driven from the front in either direction. Tramway standards of the time dictated that 'skirts' and 'cow-catchers' should also be fitted for public protection.

Twin Cab Design with Cow-catchers
Knowing 7109 inside out, I've always found these twin cab variants fascinating. In particular, being aware of what it's like under 7109's engine covers, it would not be a nice place to work! There are hot pipes and non-elbow-friendly protrusions all over the place! These locos were withdrawn from the W&U Tramway after only a short service and one can only speculate the reason. However, subsequently, they were transferred to Yarmouth docks where they gave many years' good service.

I have recently been sent a 1933 instruction manual covering the various LNER Sentinel Locos and Railcars. It includes a diagram of the layout of this Y10 double-cabbed loco. (Click the diagram to enlarge it).

General layout of both front and rear cabs
It shows how the front cab regulator lever was connected across the top of the central water tank to the regulator valve itself in the rear cab. Obviously, this loco could not be single-man operated whilst driving from the front as a fireman was still needed by the boiler at the rear.

Various identities have been suggested for Sentinel 7109 when it gets into service; however, a variant with a front mounted cab is one I had not considered until now!

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