Construction of Shedding Tappet for Plain Weave

Last Updated on 17/03/2021

Construction of Shedding Tappet for Plain Weave

Md. Rubel Miah
Department of Textile engineering
World University of Bangladesh


Experiment name:
Construction of A Shedding Tappet for A Plain Weave

The plain weave is the simplest and commonly used. In a plain weave, each warp yarn passes over alternate weft yarns. Neighboring warp yarns pass over the adjacent weft yarns. In this type of weave, the warp and filling yarns cross alternately.

Plain & Twill weave mesh holds a higher volume of ink in its cells than does plain weave. Thicker fabric thickness in twill weave mesh creates a greater adhesive force within the twill weaves cells, so it transfers less ink onto the substrate during printing than the plain weave.

Construction of a tappet:
The principle of construction of a shedding tappet for a plain weave is illustrated in Figure 1. A plain weave is generated over two picks during which the bottom shaft rotates only once. Hence, the corresponding tappet is mounted on the bottom shaft. This tappet has to keep the corresponding treadle bowl in the lowermost position during 120° rotation of the crankshaft, which accounts for dwell of the corresponding heald at the bottom shed line. This dwell duration is equivalent to a bottom shaft rotation of 60° only. Subsequently, the bowl has to be allowed to move to the topmost position over a 240° displacement of the crankshaft, equivalent to a 120° displacement of the bottom shaft. The bowl dwells at the topmost position for a bottom shaft displacement of 60° and then is pushed down to the lowermost position again over a bottom shaft displacement of 120°.

Construction of a tappet
Figure 1: Construction of a tappet

Working Principle:
At a radius of 2 inches or 5.08 cm. describe the circle A (figure 2). This circle represents the distance from the center of the driving shaft to the nearest point of contact with the tradle bowl.

Plain weave mechanism
Figure 2: Plain weave mechanism

At a radius of 3 inches or 7.62 cm. (5.08 cm. + 2.54 cm. = 7.62 cm.) describe the circle B.

At a radius of 7 inches or 17.78 cm. (7.62 cm+ 10.16 cm = 17.78 cm) describe the circle C. Four inches or 10.16 cm. are added for the lift of tappet.

The circle B represents the center of the treadle bowl when the inner circle of the tappet is acting upon the bowl. The circle C represents the centre of the bowl when pressed down by the tappet.

The pattern being a plain one, as shown in figure 2., the circles must be divided into two equal parts, and each half circle will then represent one pick. By the line DE divide the circles into tow equal parts.

Now, as the healds must have a pause or dwell equal to one-third of a pick when at the top and the bottom of their stroke, divide each half-circle into three equal parts by lines FK, GH. Divide FH and GK each into six equal parts and divide the space between the circles B and C into six unequal parts, the largest being in the middle, gradually decreasing towards the circles \B and C. To find out the six unequal parts, describe a semi-circle L between B and C at a radius of half the lift of tappet, which is 5.08 cm. Now divide its circumference into six equal parts and then draw perpendicular lines from then on the line GH. This gives six unequal divisions on the lift to obtain the desired eccentric shape of the tappet.

The plain weave tapped mechanism we know fabric structure, mechanism of plain weave, and construction. Its help my future life.

You may also like:

  1. Twill Weave: Features, Classification, Derivatives and Uses
  2. Sateen Weave: Features, Classification, Uses, Advantages and Disadvantages
  3. Differences between Tappet Shedding, Dobby Shedding and Jacquard Shedding Mechanism

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