Pattern-forming device of textile machines

The pattern-forming device is used in dobbies of weaving machines and has a removable perforated drum (1) with coding elements (2), which is mounted on a shaft (5), as well as read-off elements (4) which are arranged with a gap relative to the drum (1), with the possibility of contact with the drum (1). Each support (6) of the shaft is designed in the form of a regular polyhedral prism, the number of side faces of which corresponds to the number of exchangeable drums (1) which can be mounted on the shaft according to the particular pattern-forming program selected. The bore provided in the prism for the shaft is made at different distances from the side faces of the prism, the said distances being fixed on condition that the predetermined gap between the read-off element (4) and the drum (1) is maintained.