# Calculation of 7-Wheel Take Up Mechanism

Take up motion:
The process of withdrawing fabric from the weaving zone at a constant rate and then winding the woven cloth on the cloth roller with the continuous progress of weaving is called take-up. Take-up is to draw a fabric to the cloth roller regularly as it is woven. In this article, we will know about the calculation of the 7-wheel take-up mechanism.

7-wheel take up mechanism:
The 7-wheel take-up mechanism is a typical take-up mechanism which is generally used in cotton weaving.

Construction and working principle:

• A = Rachet wheel = 24 T
• B = Standard wheel = 36 T
• C = Change wheel = XT
• D = Swing pinion = 24 T
• E = Compound wheel = 89 T
• F = Compound pinion = 15 T
• G = Take up wheel = 90 T
• H = Take up roller = 15.05″ (circum)
• K = Retaining catch
• L = Pawl
• M = Finger
• N = Take up lever

Take-up lever N is centered at ‘I’ and has a pawl L pivoted upon it

A finger M is bolted and adjustable to a sley sword and passed through a slot in N

A swing motion is given to N and this will cause the pawl L to drive the Rachet wheel A and wet the train of wheels in motion. The amount of movement in L depends upon the position of M in the slot of N

The cloth is wound onto the cloth roller, as the sley falls back or as the sley moves forward.

Calculation:

PPI calculation:
For one revolution of one tooth of Rachel wheel (A)
= 1 pick take-up

…………………………………………………G x E x C
Then, No. of revolution of A = 1 x ………………..
………………………………………………….F x D x B

……….90…….89………X
= 1 x …… x ……… x …..….
……….15……..24……..36

…………………………………………….90      89        X
No. of picks for 1 rev. of H = 1 x ….. x …… x ……. x 4
…………………………………………….15       24       36

…………………………….90      89       X        24
Picks per inch = 1 x …… x …… x …… x ……….
…………………………….15       24       36    15.05

………90       89        60       24
= 1 x …… x …… x ……. x ………..   [C=60]
……….15       24       36     15.05

= 59.13

Pick spacing:
Pick spacing is the reciprocal of the pick density

…………………………….1
i.e. pick spacing = ……..
…………………………..PPI

………………………….B         D         F        H
Pick spacing = 1 x …… x …… x …… x ……..
………………………….C          E         G       A

…..36 x 24 x 15 x 15.05″
= ………………………………
……..60 x 89 x 15 x 24

= 0.0169 inch

Or pick spacing = X = 0.0169 inch

#### Loom Constant:

To find out the loom constant, the no of teeth in a change wheel is always = 1  i.e  X = 1

…………………G x E x C x A
PPI = 1 x ………………………….
………………F x D x B x 15.05

…………..90 x 89 x X x 24
= 1 x ………………………………
………..15 x 24 x 36 x 15.05

…………………………………90 x 89 x 1 x 24
Loom constant = 1 x ………………………………
………………………………15 x 24 x 36 x 15.05

= 0.9836

Hence, PPI = Loom constant x change wheel
= 0.9856 x 60
= 59.136

In the loom, the fabric remains under tension. When it is out of the loom, it becomes relaxed. So in a relaxed state lengthwise contraction of the fabric increases the PPI of fabric and normally contraction is 1.5%

………………………..G         E        C       . .A        .. 100 + 1.5
Hence, PPI = 1 x ….. x …… x …… x ………… X ……………..
………………………..F        D         B      .15.05         . 100

……….90      89      60     .,.24
= 1 x ……. x ….. x …… x ……… x 1.015
……….15       24      36     15.05

= 60.02

You may also like: Calculation of 5-Wheel Take up Mechanism

```Author of this Article:
Rofiquzzaman Raju
Fabric Technologist,
B.J.Group, Mawna, Gazipur
Chittagong Textile Engineering College
Contact: 01714419681```

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