The water wheel for the Grinding Hull is almost as big as the Tilt Wheel.
It is also a High Breast shot wheel, with its own pentrough fed from the dam.
The wheel axle has a gear wheel fixed to it which drives another gear wheel at a right angle. This then turns the main drive shaft inside the Grinding Hull. You can see this more clearly in the Plan of the Grinding Hull.
Each grinding wheel is driven from the main drive shaft by its own pulley wheel and leather belt.