Dunrobin - work starts on replacing the cylinder block...

Dunrobin – work starts on replacing the cylinder block…

/ September 12, 2012 / Leave a comment / Dunrobin, News
We have asked David Elliott to assist us with the work to procure a new cylinder block for Sharp Stewart No.4085 ‘Dunrobin’.  As has been documented previously, the block is very tired and can be considered ‘life expired’.  David, whose experience with the engineering and design behind the well known A1 class locomotive ‘Tornado’ as well as the J27 and G5 projects, is now carrying out a survey with a view to producing drawings from which the patterns and core boxes can be made.  He will also oversee the casting and machining of the block, ready for it to be refitted to Dunrobin.

Below: So what exactly is wrong with the cylinder block?  Here is a very good indicator that the metal is so thin in places as to have perforated!

Below: This patch, welded into place (onto an iron casting…) probably didn’t work but was an attempt to counter the thinning of the metal.

Below: A graphic example of breakage and repair!  The casting has broken away completely, despite some crude attempts to weld it.  To the left, in the shadow, is a large pool of lead, probably an attempt to seal a leak on the top of the casting.  Just at the top of the picture is the blastpipe base, to the bottom can be seen the cylinder covers and slide bar supports.

Below: I wonder if this is a patch originating with the Royal Navy (who had use of Dunrobin during both World Wars), LMS or even the Highland Railway – it appears to be older than some of the other repairs, again it reflects an attempt to make good the structure of the block.

Below: The side of the block, which is protected by the frames, shows nicely cast and substantial ribs.  Compare these to the remains of the ribs above, which now look like fossilised relics found on the seabed!  Clearly a great deal of the structure has corroded away, despite any floor in the smokebox (which would have hidden a multitude of sins!).

Below: A liner is fitted in one bore, possibly to replace lost strength caused by the corroding casting, possibly to prevent leaks through thinning walls.  New pistons and valves will also be a feature of this restoration, the aim being to give Dunrobin a tight and durable front end and ensure it’s longevity as a working locomotive in the Beamish collection.

As can be seen, there is a lot of work in this particular piece of the engine, and this forms Phase 2 of our restoration plans – significant in cost but essential to the overall success of the project.