File:Taylors Shaft Cornish beam pumping engine - drivers position (geograph 2988794).jpg

English: Taylor's Shaft Cornish beam pumping engine - driver's position

This is the bottom chamber position where the driver stands to start the engine by hand. When running and stable it is self-acting but the driver would probably never venture very far from here in case adjustments or urgent action were required. The three horizontal shafts (or arbors) work the valves and from top down work steam, equilibrium and exhaust valves. The exhaust valve is in the centre of the green casing and the other two valves are at the top of the cylinder. The engine's speed is controlled by altering the pause at each end of the stroke via the vertical rectangular frames to left and right of the mechanism. The one on the left controls the pause before the power (downwards movement of the piston) stroke and the one on the right controls the pause before the return (upwards or equilibrium) stroke.

The machinations of the Cornish beam engine are too complex for a short(ish) caption but can be appreciated fully at Kew Bridge Pumping Station in London where there are working examples.