3- Simple point pass
Center thread is the name given to the thread located at the direction changes. Here, these are the threads o fshaft frames 1 and 4
We will see later that each of these families offermany variants and possibilities and we will study the passes families that were not discussed here.
The purpose of these small studies is to give thebeginners the basic notions of the theory of weaves without going into complicated cases that do not permit the vulgarization.
The above profile represents a loom equipped with 8 fshaft rames. For moreof clarity, we have drawn only the first and last shaft frame. Wesees clearly that when these shaft frames are raised to form the opening(i.e shed) to pass the shuttle, shaft frame 1 must be lifted higher. The other 6frames have intermediate positions between this mini and this maxi. As a result,the warp threads, which are increasingly lifted from the shaft frame 8 to the shaft frame 1,are therefore subjected to increasing tensions in the threads 1 to 8,then 9 to 16, 17 to 24, etc.
The threads in the fabric will be shiny in proportion to the tension theywill have received. And this is noticeable on the fabric, in the form of bars inthe sense of the warp. Of course, this defect is mainly marked on the fabricsthe finest, such as silks for example. Mixed pass does noteliminate this inevitable defect, but makes it possible to attenuate itdividing the pressure differences instead of leaving them grouped.
This is the reason for the mixed pass ...
In this type of pass, one shaft frame jumps out of two.You notice that we used 8 shaft frames insteadof four on the two preceding examples. Why ?
Mixed pass is in principle never used belowof 8 shaft frames. This type of pass has a special purposewhich we will now explain to you:
2 - Mixed pass
In this type of pass, the shaft frames receive a warp threadsuccessively, one after the other: 1,2,3,4 - 1,2,3,4
1 - Continuous pass
Passes
There are 7 main types of passes.
In this approach for beginners, we will study only the three most classic which are:
1 / Continuous pass
2 / Mixed pass
3 / Simple point pass