toothing 84 and the worm wheel 86 is preferably constructed so as to be self locking moreover as shown in fig3 the reverse switching gear unit 10 is equipped with a brake device 92 for preventing an after running the brake device 92 comprises a friction disk 94 which is arranged on the drive shaft 88 so as to be fixed with respect to rotation relative to it and a friction disk 96 which is arranged in the housing 70 so as to be fixed with respect to rotation relative to it cooperates with the friction disk 94 a peg 98 arranged at the friction disk 96 engages in a groove 100 in the housing 70 which lies parallel to the drive shaft 88 and prevents a turning of the friction disk 96 a pretensioning spring 102 pretensions the stationary friction disk 96 against the friction disk 94 which is connected with the drive shaft 88 the drive shaft 66 is interrupted at the portion going toward the the warp let off device 2 by means of a switching coupling 104 this switching coupling is constructed for example as a claw coupling which is switchable by means of a switching lever 106 and an actuating device 108 so that the drive of the warp let off device 2 can be shut off when necessary the weaving machine is equipped with electronic control device 12 which is connected on the one hand with the dobby 56 of the shedding device 6 and on the other hand with the drive motor 9 and with the auxiliary motor 90 of the reverse switching gear unit thread regulators such as the filling stop motion 110 and.