First cylinder cast for new ‘Night Owl’
THE first of two cylinders for the new Churchward 47XX ‘Night Owl' 2-8-0 No. 4709 has been cast – giving renewed hope that the locomotive could be ready by the builders' target of 2023/4.
However, the landmark success has followed a series of delays caused by the Covid-19 pandemic, compounded by technical issues. Indeed, the day when the patterns arrived at the foundry to be cast, that company went into receivership – leaving the project team to search for a replacement to do the job.
Paul Carpenter, chief engineer of the Great Western Society's (GWS) 4079 Group, which is building the 10th example of the class, said: “Premier Patterns in Smethwick produced the polystyrene patterns, which were completed and inspected during February 2020, then dispatched to the Shakespeare foundry in Preston for casting.
“This foundry had successfully cast locomotive cylinders using poly patterns for several other projects, but luck wasn't with us. On the day our patterns arrived at the foundry, the company was placed into receivership.
“We were fortunate to be able to extricate the patterns from the receiver and the search began for another foundry. We quickly discovered that in our modern manufacturing world, the number of suitable candidates is significantly less than a century ago, when 47XX cylinders were first being cast.
“We contacted every foundry currently producing cast iron products, only to discover little enthusiasm for the project. Either the sheer size and volume of the casting, or concerns centred around the specialist knowledge required to work with poly patterns, caused most to decline to bid for the contract.
“Months were spent in detailed discussions with one foundry, only to have them decide at the last moment that they too could not deliver the castings.
“Background enquiries identified one specialist – a man who had worked successfully with polystyrene patterns to produce locomotive cylinders.
Determination
“From the first discussion with Alan Boulton, it was obvious that he was a man with both the specialist knowledge and a genuine enthusiasm to deliver this work. He clearly possessed the ‘can-do mentality' required, and on his recommendation, Boro Foundry (in Sour Vale Road, Lye, West Midlands), was contracted to deliver our castings.
“This foundry has often undertaken work for our parent GWS, and are currently machining the coupling rods for the County 1014 Project. With a full team and the necessary skills and experience on board, Boro Foundry's Sam Edwards, Alan, and the 4709 Group engineers started on the research and development work necessary to ensure the casting process would succeed. Working as a single unit, the team re-engineered the casting process for steam cylinders with poly patterns from first principles.
“It's taken a year of hard learning and steely determination, but finally, at the end of a tough year, the first casting is complete.
“The success of this project represents an important development for the casting of locomotive cylinders for our heritage world. Without doubt, Boro Foundry is now the centre of excellence for this specialist work, and we are grateful to both the team there and to Alan Boulton for their commitment to the challenge.
“We are also grateful to our good friend Mike Solloway who, on our behalf, has made regular site inspections. His experience and knowledge from casting cylinders for his own engine has been invaluable.”
Group treasurer Richard Croucher said: “Bob Meanley was invited to produce drawings for the cylinder block redesign and his drawings would surely have delighted Churchward himself. In addition to his work as a first-class locomotive engineer at Tyseley Locomotive Works, Bob is also an excellent draughtsman. On top of his work on the cylinders, he has also produced detailed drawings to allow new front and rear cylinder cover patterns to be made.
“The pattern for the second cylinder block is now being prepared at Boro Foundry and a date for the cast is anticipated shortly. Once both blocks are completed, they will be stress relieved in a furnace before being delivered to our machining specialist, who is ready to start work.”
The new cylinder blocks have been redesigned and manufactured to bring the width and height within the current Network Rail loading gauge – essential for future main line running and similar to the design adopted for GWR 4-6-0 No. 6024 King Edward I.
Components
Bob has also produced an assembly drawing to show how to best fit the donor 41XX pony truck to No. 4709. This last drawing was essential to support the work on the pony truck by Leaky Finders, in Exeter, and ensures that all the many critically important interface details have been addressed.
Timber patterns for the new cylinder covers, as well as the two huge compensating beams, have now been ordered.
The 47XXs were designed and built between 1919 and 1923 to haul overnight fast vacuum-fitted food trains into London from the west and the Midlands, but quickly found use on freight duties across the GWR network. They were called ‘Night Owls' because they were primarily designed to work during the night and could be seen simmering in the daylight awaiting nocturnal duties.
Their reliability, power and route availability later saw them hauling holiday passenger services with great success. In recognition of this latter-day role, class members were outshopped in fully-lined express passenger green livery from about 1957 onwards. All nine were withdrawn between 1962 and 1964 but none were preserved.
➜ Donate to the ‘Night Owl’ project at https://didcotrailwaycentre.org.uk