Wednesday, 20 April 2016

Cylinder Replacement Programme is launched

So why replace the cylinders?

What indeed?  The existing set of cylinders was cast in 1910 and installed into the locomotive, it is believed, or at least we have not seen any records to suggest otherwise!  This coupled to the locomotive being dismantled in the early 1980s for a "quick repair" and being open to the elements ever since has had a greatly detrimental effect on them. We found that, not only was the outside of the existing set pock marked and covered with surface rust, there were also delaminated rust and even a perforation within the castings.


Top view of the existing cylinders showing the perforated casting
A very shabby set of removed cylinders showing the delaminated Cast Iron

As if it did not look bad enough in the pictures, measurement and gauging took place and the worst was confirmed.  we would need a new set!  In all honesty, with recent experience on other locos a repair would be a false economy as the work would need to be carried out sooner or later, and probably sooner.

The original Ashford drawings were obtained for the cylinders and converted into a CAD drawing by Matt Holloway, who then produced the 3D CAD model.

A detailed copy of the original Ashford drawing redrawn in CAD by Matt Holloway

After many a long night and squeezing in his day job and social life, Matt still managed to produce a fine set of drawings and CAD 3D models which, after checking will be used to produce at least two sets of cylinders.

This is the view showing the two half sets of cylinders joined together
The view above shows the assembled castings which will be used to produce the complete set of cylinders.  The dimensions are being checked and allowances for shrinkage calculated and added to the models before the next stage can be carried out.

The next stage will be to produce a set of patterns.  This will be done using 3D printing techniques in polystyrene. There will be two castings for each set of cylinders one for the right and one for the left half of the set.

Once the patterns have been made, a sand mould will be created ready to pour the grade G17 Cast Iron. This will produce a set of cylinders, or at least the rough castings.  When the castings have been allowed to fully cool and removed from the sand mould they will need to be set aside to "season". This involves putting them on a pallet, placing them in the works yard and forgetting about them for up to a year.  This process relaxes the castings and all, or certainly most, of the stresses within the castings will be relieved.

The technical bit then starts!  the rough casting will need to be machined on all of the faces that are in red on the 3D models.  There are two schools of thought on this. the machining can take place in house or be sent out to a specialist machinist.  The cost is likely to be similar.  Whilst the in house method would be cheaper per hour, it is likely to take longer to carry out the work conversely, the external specialist will be more expensive per hour but will take less time to carry out the work.

At the end of the day, it will be the Project that needs to pay for the castings and machining. This cost will be in the region of £8,000 for the rough casting.  On top of this will be transport and machining.  this is believed that this will probably double the cost to in the region of £16,000.

If you or someone you know would like to help sponsor the cost of the cylinders, please ask them to contact the fund at  or the Just Giving site  can be used.  We also have a standing order scheme which is run in conjunction with the Bluebell Trust, for details of this please contact the fund on the email address above.

Thank you for your continued support it is always much appreciated.

Clive D Emsley (Restoration Project Manager and chairman of the Fenchurch Fund)

No comments:

Post a Comment