Ian
The use of a horizontal steam engine (or an oil engine) would have been the
most common way of operating a set of 'Cornish' pumps on a new installation
any time after about 1900 when the conventional beam engine was being phased
out in new builds.
It is unlikely that the flat rod would have been operated off the flywheel.
You would be looking at, maybe, 4-12 strokes in the shaft which indicates a
flywheel rpm of 4-12, which is impossibly slow for horizontal engines.
Normally the engine would drive a separate wheel, via gearing, from which
the flat rod would be driven. The other point is that the pumping
requirement would vary depending on the make of water which in a shallow
mine could be very weather dependent. One way that this can be done,
without monkeying about with governors, is by having a number of flat rod
attachment points on the radius of the driving wheel. The stroke of the
pump in the shaft (an thus the pumping rate) can be varied depending where
on the driving wheel the flat rod is attached. The closer to the
circumference the greater the stroke of the pump. This reduces the load on
the engine yet still permits it to operate at optimum rpm.
Regards
Tony Brooks
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