From David Young's Workshop...

From David Young’s Workshop…

8th December 2010
While the snow and subsequent freeze has had a major impact on progress outside, volunteer David Young has taken confinement to his workshop in his stride! The result is the first machined clack valve for Lewin and some substantial progress on the additional water pump for the Steam Mule. The latter is also gaining a brass pole frame that will support a tarpaulin.
Below: The clack valve (or non-return valve to the boiler in alternative parlance) for Lewin. Note that it is the same as those made for Coffee Pot No.1, in fact we are waiting a further three sets of castings for these components as the first batch of three were flawed. One will be fitted to Coffee Pot No.1 for next season, two are for Lewin and one is for Coffee Pot No.17 (one day…). There are also some spare components. The standardisation on this valve ensures we can hold some spares as well as quickly swap between items where mounting holes allow. I expect we would use the same type on Malleable No.5 given the chance! The type is based on No.17’s original, which is very similar to those appearing in photographs of No.18 (Lewin).
The valve consists of a body casting, an insert, valve itself, restricting nut and threaded bolt (which controls the lift of the valve and enables the valve to be shut – not fitted on the original but deemed by all operators as a prudent improvement – a stuck clack that cannot be isolated can be problematical).
Below: Meanwhile, the Steam Mule has gained this pump, which works on the bi-pass principle and is driven off an eccentric on the end of the crankshaft. This will enable us to train staff in an important feature found on road engines, and gives the Mule its third means of putting water into the boiler (engine driven pump, hand pump and injector). Once again Dave has excelled in making this component both fit and in the machining work required on a small and involved casting.