Arrangement in a sewing machine.

摘要

This invention implies a design of a sewing machine in a rational way, where the bed shaft and the arm shaft have been replaced by a synchronous belt (19) and where the plane of rotation of the synchronous belt is perpendicular to the cloth feeding direction. The solution implies that all function units which drive or are driven by the synchronous belt and the belt itself are mounted on the same side of the sewing machine body which is a very great advantage in view of assembly technics. In the driving system there is a number of backing rollers (20-26) which guide the synchronous belt in the plane of rotation. These backing rollers are entered on shafts which are either stationary or driving. The shafts are then supported by the sewing machine body in rotation or stationary manners. The backing rollers can be smooth or toothed wheels which drive or are driven by the synchronous belt. Then, some toothed wheels can drive several function units of the sewing machine. By changing the diameter of the toothed wheels in relation to each other the time relation between the several function units of the sewing machine can be controlled. Another advantage with this invention is that the driving motor can be connected to one of these toothed wheels directly, thus driving the several function units via the synchronous belt without intervening primary transmission.