Smokebox Saddle Machining – Steam Locomotive 4709 Update
The 4709 Group has released its latest update on the construction of tenth Great Western Railway (GWR) member 4700 Class No.4709.
Great strides are being made by Brierley Hill-based Roach Precision Engineering in machining the saddle and smokebox cylinder block.
Using their modern CNC machine, the Roach team will make straight cuts back and forth to produce the necessary curves to allow the smoke box to fit properly.
Examination of the extension frames showed that some welds, made many years ago, had defects which are currently being corrected.
Once this work is complete, the extension frames will be delivered to Roach, where holes in the main cylinder block can be drilled and tapped. Although the holes can be drilled based on drawings produced by Swindon Locomotives Works, the best plan is based on the holes in the cylinder block over those in the extension frames, ensuring that the two fit together perfectly.
Once this work is complete, the cylinder blocks can be transported to Tyseley Locomotive Works, where the team can begin building the front end of No.4907.
Four piston valve liners have been cast and are being shipped to Roach where they can be custom machined. This now leaves the piston crowns and valves as the last elements of the cylinder assembly to sink.
For more information or to support Group 4709 in Building #4709, please visit their website here
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