Paul,
I would be inclined to believe the figures of 10ft. stroke in the cylinder and 9ft. stroke in the shaft for the 60inch engine at Snailbeach from the 1884 Inventory (and the PDMHS article by Mike Gill and Hazel Martell).
As for the distances you mention, from one of my notebooks:
Distance from the centre of cylinder bed to the centre of bob wall = 5.82m (19.09 ft. or effectively 19ft.)
Distance from the edge of shaft nearest engine house to centre of bob wall = 4.295m (14.09ft or 14ft.)
If you add about 1ft. for the distance of the pumps from the edge of the shaft, that would give you a distance of approx. 15ft. from the centre of the bob wall to the pump rods.
I would be interested in the equation you use to convert these horizontal distances into the vertical distance travelled by the piston. I would have thought that you need to have some idea of the vertical height of the cylinder itself.
Cheers
Kelvin Lake
Publications and Newsletter Officer
Shropshire Caving & Mining Club
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-----Original Message-----
From: mining-history [mailto:[log in to unmask]] On Behalf Of Paul Smith
Sent: 29 April 2014 23:28
To: [log in to unmask]
Subject: Re: Snailbeach
Thanks Andy, I now have your article about the Snailbeach machinery, and find your argument compelling about the year of installation of the 60 inch engine, it makes a lot of sense, I am hoping to visit Snailbeach again in May/June time, equipped with measuring instruments, I now have the information I need to estimate the strokes from measurements of the engine house cylinder loading and balance bob slot. But the 10ft indoor, 9ft outdoor stroke seems most likely, as the pumps were in the main shaft 9ft pump stroke is probably correct as stated, it is the engine stroke which seems to be recorded wrongly, 6ft stroke for a 60 inch engine seems very small. The 10ft stroke mentioned in the PDMHS journal is probably the correct measurement.
Measuring the approx half length of the beam seems the best way to prove this. The indoor half of the beam would have to be very short for a 6 foot engine stroke! (Only about 10ft from beam from centre gudgeon to the cylinder end gudgeon). Whereas 9ft stroke equates to approx 15ft from centre to pump rod gudgeon. Even allowing for different positions of the centre gudgeon on the bob wall, the measurements of the engine house should be accurate enough to estimate both engine and pump strokes. Certainly to prove which stroke is the longer, engine or pump.
It would be good to know who manufactured this engine, but by the sound of it the records of this time are very incomplete.
Anyway thanks for a very interesting and informative article on Snailbeach.
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