Engineering as art
For the uninitiated, engineering design is little more than a spaghetti of lines on huge sheets of paper. To the experienced and informed, those designs reveal intricate and critical dimensions and detail, eventually, enabling something to be made, or built.
Plan or elevation, section, general arrangement, or any number of other views, including the tongue twisting orthogonal view, there’s a beauty to the reality of engineering detail. In recent times, computer aided drawing (CAD) has supplanted the traditional draughtsman, his drawing board, pencils, pens, drawing instruments, templates and T-squares now simply a part of history.
But not quite.
As a matter of choice, a lot of the preparatory work on 4709, especially the planning for new cylinders and latterly, the plan to mate the pony truck from a Barry survivor to this re-creation, has provided a rare opportunity for some old school drawings, as 4709’s Paul Carpenter explains;
“Since the 47XXs were designed almost a century ago, the loading gauge requirements have been changed. If our loco is to run on NR’s main line, the new cylinders we were committed to, had to be re-designed to comply.”
Paul approached Tyseley’s Bob Meanley to undertake the design work. Bob opted for the traditional design methodology, culminating in the first cylinder casting emerging from the foundry just a few days ago. The second is due to be cast shortly.
“In addition to getting the job done, for an engineer, Bob’s drawings are a thing of beauty. Hand drawn, highly detailed, accurate, dimensioned; just as Churchward’s drawing office might have produced.”
More recently, Paul asked Bob to also produce drawings to permit the (re)use of the donor 41XX pony truck on 4709.
“The assembly drawings are for the pony truck and identified several important differences that have had to re-engineered to achieve the functionality we required. A look at Bob’s work, especially the huge counterbalance beam will give you an idea of how important this work has been.”
The Compensating Beam, vital to keep the pony truck stable on the track and critical to main line working, will be cast from a wooden pattern, developed from Bob’s drawings.
“CAD’s great, but there really is nothing like hand drawn detail. It’s the soul of great design work.
Perhaps one day, we’ll have some prints framed and hung in the museum at Didcot to remind people what could be done with basic drawing tools and a lifetime of skill and experience.”
