Also here are the tentering of the grinding couples and the great spur wheel. The camshaft is driven from the crankshaft by spur wheel. This carries a wooden compass arm Great Spur Wheel. The great spur wheel is also of cast iron. The Great Spur Wheel is also of cast iron. Millstones driven by the "Great Spur Wheel" can be either "Overdrift" or "Underdrift". The Great Spur Wheel is diameter and has 92 cogs. A large flywheel and drive shaft drove a single-reduction spur wheel drive. The wooden great spur wheel was of compass arm construction. The wooden Great Spur Wheel was diameter, with 120 cogs. The wooden Great Spur Wheel drove three pairs of millstones. The cast-iron spur wheel is diameter with 66 cogs. The great spur wheel was a cast iron wheel with wooden cogs. The cast iron great spur wheel drives two pairs of underdrift millstones. The great spur wheel is a replacement, built by Mr Dallaway.