Abbeydale: Blowing Engine
at Abbeydale Industrial Hamlet near Sheffield.
This small blowing engine supplied blast air for the adjacent forge. The two cylinders ('tubs') are single acting, but are each given three strokes per revolution of the waterwheel, due to the use of three lobe cams on the waterwheel shaft. To avoid the complication and friction of piston rods and their guides, the pistons are mounted solidly on the connecting rods, and these are made to rise and fall by the cams via long rocker beams. Inevitably there will be a small degree of rocking of the piston in the cylinder, accommodated by the flexibility of the piston packing.
Air is drawn into the cylinder by a pair of flap valves in the bottom of each piston, and is exhausted through a non-return valve in the top of the cylinder.