The flagship of the Apedale Valley Light Railway is the 1917-built Kerr, Stuart locomotive called Stanhope. Why the flagship? It's easy to drive, will steam with a candle in the firebox and runs like a well-oiled sewing machine. Except that the sewing machine has recently developed an annoying minor rattle in the valve gear. Steam locos do this due to the multiplicity of bearing surfaces running in a hostile environment. Stanhope has the Hackworth valve gear with marine-type bearings. The Hackworth valve gear has the advantage of being cheap and simple to make, and the disadvantage of just about everything else. A key issue is that the valve events depend on how the loco sits on its springs, which is a function of how much water is in the tank and how many pies the crew have eaten that day. That said, Stanhope always goes well, and has shown up many other locos on outing to places like the Ffestiniog.After a game of Hunt the Clank, the usual suspect was found to the cause. This is the small end bearing, which is rather under-designed, and for which the lubrication arrangements are indifferent (at best). The bearing is now being rectified, and hopefully Stanhope will be back in full-on Singer condition in the near future.
