Tappet shedding mechanism ( Negative shedding).
The shedding motion is the first primary loom motion. " The process of diving the warp sheet into two layers by the manual or mechanical process is called shedding motion. The layers are formed by heald shafts. Since we know that the ends get drawn through the eyes of heald wires and when some of the heald shafts get raised and the rest of the heald shafts get lowered, a V - shape passage in front of the reed for weft insertion is formed. This V-shaped passage for weft insertion is called a shed.
Structure of negative tappet shedding mechanism:
In this negative tappet shedding mechanism, two tappets are used. The tappets are mounted on a countershaft.
This countershaft receives rotatory motion from the bottom shaft through spur gears.
The countershaft makes one revolution when the bottom shaft rotates for one revolution for a plain tappet shedding mechanism.
Two treadle levers are used. The anti-friction bowls are also mounted on these treadle levers.
Each tappet touches to respective anti-friction bowl. The tappets are mounted in such a way that the lifting position of both tappets is kept just opposite to each other.
The treadle levers are connected to the healed shafts with the help of jack bars.
The top side of each healed shaft is connected to the reversing roller with the help of a leather strap.
Two leather straps are used for each head shaft. The method of connection between the healed shaft and reversing roller through leather straps is shown in the below figure.