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The Threshing Machine and its Operation

Inside the Windmill Museum there is a beautiful working scale model of a Threshing Machine built by Michael Fisher and donated by his Mother.

In spite of the number of years we have had this beautiful model threshing unit in the Windmill one wonders whether we can all explain how a full size live threshing machine worked or even the reason for such an outfit in the first place. 

Why did we need such a ponderous, heavy machine? This was one of the first daily chores in agriculture to be mechanised and its purpose was to separate the grain from the straw as cereal plants, in sheaves, were fed into it. Before such mechanisation was available the job of beating out the grain from the straw was carried out by hand, wielding a heavy flail, beating at the straw on the barn floor. 

On the model the steam traction engine is to be seen. This drives the belt which powers the threshing machine. It was fuelled with sacks of coke, started and helped with small coals. In later years diesel tractors took the place of steam traction. Travelling was faster, setting up was easier, and there was no need to wait until a water boiler was hot enough to use on full working pressure.          

The friction belt was set to drive the main shaft of the threshing drum set high up inside the machine. Sheaves of grain, maybe oats, wheat, barley or rye are fed sideways into the drum, generally off a travelling canvas feeder. The strings on the sheaves are cut to allow the straw to be fed to the drum evenly and without overloading. 

The grain now fell into chutes as it was separated. These can be seen under the thresher end nearest to the engine by the driving belt. The two left hand chutes collected the prime grain, the next two held the lesser grains and tail corn, and the farthest chutes filled up very slowly with all the dust, weed seeds and rubbish. 

On the side of the thresher on the left there was a chute divided into two outlets with a lid to shut one whilst the other was filling. This was the chaff-collecting box. Chaff was used as apart of a working horse’s rations and was also used as pig bedding and chick litter. When horses were no longer available to make use of the chaff it was blown among the straw which was travelling on reciprocating arms to feed it to the baler at the end of the whole operation.   The baler used an arm with a big square head to press the straw into its feeding chamber. As this arm rose up to collect more straw the baler ram compressed the straw left by the feeding head. As the ram drew back to reload, the head would bring down more straw; The grain was raised in sacks via the sack hoist to the top or “Grain Floor” where it could be gravity fed to the rest of the mill. Here it was tipped into a grain bin which was set into the floor and which could hold about four sackfulls of grain. It passed down a wooden chute into a “stone hopper” above the stones and via an adjustable gate into an inclined “shoe” which dropped it directly into the eye of the revolving millstone. 

The shoe was suspended at the upper end by chains and its level adjusted by a crook string at the lower end. The shoe was inclined but the grain would not flow unless shaken. This was achieved by the contact of a wooden “rap” fixed to one lip of the shoe, with the corners of the revolving square-cut driving shaft (quant). The faster the stones turned, the more the shoe was shaken thus allowing a greater flow of grain onto the stones. 

The miller, working on the meal floor below was warned that the stone hopper was nearly empty by a simple, yet ingenious device, a bell attached to a leather strap fixed to the inside of the hopper could be brought into contact with the quant. The middle of the strap, depressed by the weight of the grain in the hopper was released when the hopper emptied, dragging the bell against the revolving quant, thus emitting a noise something like an alarm clock. 

The grain fed into the stones was caught in the furrows and ground as it passed outwards, the resulting wheat-meal being contained between the stones and their casing, the “stone-vat”. It then fell down through the metal spout to the control floor where it was collected in sacks. 

This product was pure wholemeal flour which could be used to make rich brown bread with all the nourishment of the whole grain in it. However in the latter years of milling, the public began to prefer white bread, which meant the wheat-meal had to undergo a further process. It was passed through a flour dressing machine, a cloth-covered “bolter” in the early days which was later superseded by a “wire machine” which effectively sieved the flour into three grades and removed the bran which was then used principally for animal fodder. 

The bale would be wire-tied after threading the wire through a square steel “needle” which separated the bales. As stronger fibre twines became available, bales became tied with these strings instead. The bales were made lighter and there were no more snapped off short lengths of wire being eaten accidentally by cattle as they fed. It could often prove deadly.