Abstract: In a position indicating device, especially for an industrial sewing machine, with a slotted wheel (3) and a first track (6) of slots (4) having, e.g., 512 slots (4), to permit a null-point synchronization over a relatively small range of rotational angles, and the establishment of definite angular positions, a second track (8) with slots (7) of various widths is provided. The first track (6) of slots (4) is associated with two light barrier arrangements comprising emitters (11a, 11b), receivers (12a, 12b), and masks (13a, 13b) while the second track (8) is associated with one light barrier arrangement. Evaluating systems are connected to the receivers (12) so that, on the basis of the number of slots (4) of the first track (6), the size of the slots (7) passing in each case and corresponding approximately to a multiple of the slot width may be determined through evaluating systems (14, 28) connected to the output, and in this manner to define the rotary angle position.

Abstract: In a drive for a sewing machine, especially an industrial sewing machine, with a needle that can be reciprocated between an upper and lower end position by a sewing machine main shaft, in which the drive is in direct driving connection with the main shaft and can be controlled at variable speed through a control system, provision is made for improving the dynamic performance of the combination of drive and sewing machine by equipping it with at least one input switch connected electrically to the control system for the input of command pulses for the step-wise actuation of the drive such that with each command pulse a certain, defined amount of movement of the drive and hence of the main shaft is triggered.

Abstract: In the drive for a textile working machine, for the synchronized yet independently operable drive of at least two shafts, brake-clutch units associated with each shaft are provided, which are driven by a common electric motor. To achieve a regulation and control having good dynamic properties and fast response, provision is made for the brake-clutch units to be controlled such that the rotatory speed of the driven shaft of the first brake-clutch unit is given as a required value, and the rotatory speed of the second brake-clutch unit is synchronized through the rotatory speed of the driven shaft of the first brake-clutch unit, systems being provided for establishing the rotatory speed ratio.

Abstract: A device for detecting an overlapping edge of material on a sewing machine has, in combination, a signal-level discriminator and an optical waveguide. The optical waveguide has a light-receiving end on the sewing machine for receiving light through the overlapping edge of the material. The optical waveguide may be an optic fiber which, because of its small, flexible size can be accommodated easily even in the crowded sewing head or bed of an industrial sewing machine. The other end of the optical waveguide is remote from the light-receiving end for providing the received light to the signal-level discriminator which, therefore, is also remote from the crowded sewing head or bed of the sewing machine which, in addition, could interfere with its operation.