Claymills Buxton & Thornley Dynamo Engine


The engine was got running but showed a few problems that may need seeing to, knocking, compression/early steam admission at one end. An indicator diagram was taken which showed it to be asymetric which pointed to poor adjustment of the valve gear.
Claymills Buxton & Thornley dynamo steam engine
The engine has an unusual valve gear in that the governor lifts a stevenson link expansion arrangement to vary the steam admission with increasing speed, There are two elements to the slide valve to achieve this.
Back in 1999 there were many discussions as to why it had the knock and extra compression at one end, I eventually wrote a simulator that showed the same effects and was then able to see the error in design where the eccentric rods are a bit short along with the lifter this changes the angle of operation relative/timing of one end compared to the other end of the cylinder.
Text file of engine measurements taken back in 1999