The Penstock

The penstock acts as a vertical gate within the pentrough to control the quantity of water flowing onto the top of the overshot waterwheel. As the water fills the waterwheel 'buckets', the weight of the water starts the wheel rotating. The power produced by the waterwheel turns the pitwheel, and the pinion on the main horizontal shaft, to drive the Millstones through the bevel gears, stone nuts and stone spindles. The main shaft also carries a large wide-faced pulley that powers an overhead shaft fitted with a pulley wheel for the canvas belt driving the Aspirator in the Garner.

The penstock control is located inside the mill, close to the Meal Bagging area and within easy reach of the miller. The lever, when moved around the semicircular board, rotates the penstock chain drum to raise or lower the penstock in the pentrough outside. This controls the flow of water from the pentrough onto the Waterwheel which in turn controls the rotational speed of the waterwheel and the millstones. A sluice gate is installed upstream of the pentrough to control the quantity of water, or to stop water, entering the pentrough.

The Pentrough and Penstock were renewed in 2014 to replace those that were installed during the restoration in the 1970's.