I've been asked to sort out a model of a lancashire mill engine and I can't for the life of me understand how it was meant to work.
The engine is a single cylinder steam engine with the steam chest on top of the cylinder. Instead of the usual single slide valve arrangement (a la Stuart Victoria), it has two rods driven from individual eccentrics, but the eccentrics throw is aligned ie there is no angular difference in the throw of the eccentric. Through an arrangement of levers two rods for operating the valve gear emerge one vertically above the other. At this point the timing of the action has moved from being in phase to being in anti-phase. The lower rod drives what appears to be a conventional slide valve covering three ports, though its difficult to be absolutely sure without stripping this down (I can't get at the underside of the valve). The upper pushrod is connected to nothing in the steam chest, whatever valve it was supposed to drive is long gone. There is too many hours work in the model for all that assembly to be a dummy (assumption).
I've drawn a complete blank as to how this valve gear was intended to work or what the missing valve looked like - hours of fruitless Googling has revealed nothing like this.
So I've tried to sketch the valve chest side on
And provided this photo of the valve gear arrangement:
Any ideas gratefully received -
TIA
Steve