He said, "You will farm for seven consecutive years. But whatever you harvest, leave it in its spikes, except for the little that you eat." Then after that will come seven difficult ones, which will consume what you have stored for them, except for the little that you have preserved. Then after that will come a year that brings relief to the people, and during which they will press. - Quran, 12. Joseph (Yusuf) (47-49)
The sack hoist (also called sack tackle) consists of a chain between the lower and upper floor and a system of pulleys and belts. It serves to transport the wheat sacks to the millstone attic.
The chain that lifts the sacks wraps around a beam on the first floor. The engagement and disengagement is performed with a pulley (see point B in Illustration #18). This pulley is driven by a belt and by a second pulley in constant movement (see point A, the direction of the movement is indicated with a black arrow). To start the sack hoist, the miller pulls a rope that is connected to a wooden bar. The bar moves a smaller pulley, which is called pressure pulley. The latter one tightens the belt and drives the first pulley with the chain.
The illustration shows the movement of the pressure pulley, the upper pulley and the chain, indicated by green arrows. The numbers indicate the sequence.
The disengaged sack-hoist is shown below on the left, the engaged sack-hoist on the right.
The sacks are lifted to the millstone attic through a trap door in the floor, which consists of two boards, each of them mounted on two hinges. To disconnect the sack hoist, the miller lets go of the rope: the pressure pulley moves away and releases tension on the belt. The sack remains suspended at the desired height and can be moved around to pour its contents into the milling separator.
The sack hoist works in an extremely simple way and makes the miller's task much lighter.
Where we will see how to remove all impurities prior to the milling process and use a sieve to remove the smallest grains.