How does the mill work?
In 2012, John Brandrick a mill enthusiast and technical drawing guru charted and then drew the internal workings of the mill in 3D style technical detail. The results of his drawings of Charlecote Mill and many other UK and European mills can be seen on his website. By viewing John's drawings you can get a sense of how all the different gearing elements work together to provide drive to the mill stones as well as power for the sack hoist. Of course the best way to appreciate this is to visit the mill on one of our OPEN DAYS where one of our experts will explain it to you, close up and in detail.
Charlecote Mill operates with two undershot waterwheels, each of which is some 18 feet in diameter, one to the West end of the mill and one to the East. As shown above (this is not Charlecote's wheel), an undershot wheel requires a "head" of water at the rear of the mill that is controlled by a sluice gate or control gate to allow it to flow onto the close fitting paddles of the water wheel. Crucially, there is then a fall of about 2 feet before the water flows away into the Tail Race at the front of the mill.
The water level in the Head Race at the rear is rarely a problem, although sometimes a bit more would be nice in the high summer season. The important aspect is the ability of the water to flow away into the Tail race to maintain that fall. If the water level increases in the tail race during flood times (making it the same or similar height as the Head Race) you can imagine from the image above that as the wheel rotates, the paddles from bottom centre to the front of the wheel are trying to lift the water and that balances out the power that has been created at the back of the wheel. This is known as back watering and will prevent the mill from running.
The water in the Tail Race flows away to the River Avon from where it originally came. Keeping the tail race clear of debris to allow this water flow away from the water wheels is an essential part of mill maintenance and includes regular removal of reeds and silt build up.
The water level in the Head Race at the rear is rarely a problem, although sometimes a bit more would be nice in the high summer season. The important aspect is the ability of the water to flow away into the Tail race to maintain that fall. If the water level increases in the tail race during flood times (making it the same or similar height as the Head Race) you can imagine from the image above that as the wheel rotates, the paddles from bottom centre to the front of the wheel are trying to lift the water and that balances out the power that has been created at the back of the wheel. This is known as back watering and will prevent the mill from running.
The water in the Tail Race flows away to the River Avon from where it originally came. Keeping the tail race clear of debris to allow this water flow away from the water wheels is an essential part of mill maintenance and includes regular removal of reeds and silt build up.