Boscastle Locomotive Limited
27th October 2011
The photo below shows part of one of the main steam pipes, these two extension pieces sit on top of each outside cylinder at the point where the superheated steam enters. The steam tight faces and studs on the extensions were all worn or corroded.
The small flange on the side is where the snifting (or anti vacuum) valve is fitted. When the locomotive is coasting and no steam is entering the cylinders, this valve drops open and allows air in. This prevents the superheater tubes from overheating and also prevents ash being sucked back down the blast (exhaust) pipe by the pumping action of the pistons.
The photo above shows the re-furbished steam pipe sections.
All of the main surfaces that form a steam tight seal have been skimmed in a lathe by one of our volunteer machinists.
The snifting valve face has been re-cut on a milling machine and polished smooth, new studs have been manufactured and fitted.
These components are now ready to fit to the cylinders.