Other factors which count against mechanical tuckers are the comparatively large amount of damage caused if the mechanism fails and the loss of production time and reject goods which are a consequence of this.

Since fabric woven on airjet weaving machines reacts differently to each style and pattern in terms of contraction behaviour, the mechanical elements of a conventional tucker must be matched precisely to each new contraction width. Any change in quality or width or a switch from split to tucked selvedges therefore involves a considerable amount of mechanical effort.

The nature of the task of developing a new generation of tuckers - the Pneuma-Tucker- was thus defined for DORNIER. The use of mechanically movable, draftdependent parts was to be avoided. Furthermore, the system had to be capable of being controlled via the DORNIER AT electronics system.

The new Pneuma-Tucker has three electronically controlled functions: cutting, holding and tucking. while "cutting" is performed by electronically controlled scissors, the "holding" and "tucking" functions are performed exclusively by means of directed air flows.

These functions can be changed with a large degree of transparency for all tucked selvedges in the weaving operation in such a manner that the quality and depth of tucking can be matched to the requirements of the style. Moreover, the electronic control system facilitates tucking of the filling thread regardless of the design.

To be able to match the thickness of the selvedge accurately or change it in finely graduated increments depending on the fabric quality, picks can be tucked singly or in groups of two, three, four or more threads. This option is now available in addition to the two so far known and limited variations, i.e. thinning of the selvedge threads and a change in the weave construction in the area of the selvedge. Thus a significant extension of selvedge design and adjustment can be achieved. Any corrections required can be entered quickly and easily via the machine display.

Since no mechanical drives are required, very narrow fabric widths of less than 25 cm can be set, with no exchange of width-dependent components needed in the event of a width change. The conversion from split to tucked selvedges and vice-versa takes just 30 minutes.

The decisive advantage is that the high speeds of single- and multiple-width airjet weaving machines can be realized reliably and stable in the long term without a high outlay on maintenance because the mechanical tucking unit is eliminated.

Filling waste on the filling insertion side is eliminated completely when using the DORNIER Pneuma-Tucker. On the catch side it is possible to work with a catch selvedge, or alternatively the cut-off yarn ends can be removed by means of a suction system.

The functional reliability of the filling monitoring facility for yarn arrival and yarn breaks remains the same as for split selvedges.
The Pneuma-Tucker is already being used successfully for abrasive materials, coating fabrics, tyre cord and terry fabrics. It can be assumed from this that the application spectrum will be extended even further in the future.