Power-link

Today I was searching the Great Hall at the National Railway Museum (York) for potential photographs. I don't want to photograph complete locomotives, everyone does that and anyway you can easily buy professional photographs of the 'Mallard' and the 'Flying Scotsman' in the NRM shop. I spent hours today looking at the way these locomotives work and the way they are driven. It all comes down to linkage. So, here is a power-link. No doubt someone will identify the locomotive from just this bit anyway.
The Flying Scotsman is currently in the workshop for those that want to know.