It’s not often you get to see the windpump at Thurne moving but luckily today, they had a mill in motion open day. The gentleman guide explained how the mill operates and what the each part does.
The chain at the rear of the mill changes the pitch of the blades on the sails, controlling the speed that sails rotate. The rope at the rear is the brake for the mill and the fantail moves the mill’s cap in the direction of the wind. It takes approximately 5000 revolutions to rotate the cap 360 degrees. The guide also explained that typically, Norfolk windmills have boat shaped caps because at the time of construction, the craftsmen only had experience in building boats.
The gears of the mill are also a mixture of metal and wood, the reason for this being that some mills were used to make flour and metal on metal could result in sparks being created. So gears were constructed out of wood and metal to prevent sparks. It also is easier to fix a wooden gear if one of the teeth were to break compared to a metal gear.
Although Thurne mill is a drainage mill, its main use was to maintain and control the water level for the surrounding marshes. In the winter when graze was low for cattle, the mill would pump water into the marshes in order to aid grasses to grow.
The mill has a turbine which sucks water from the marsh level up to the river level into the River Thurne through a one way door.