A device for adjusting capsule thread brakes in twisting machines having inside the twisting spindle a capsule thread brake has a brake ring disposed on a brake ring support which may be moved against a spring force. On the brake ring support a ring piston is arranged, which is guided in a ring cylinder connected to a compressed air supply line. A first toothed segment with downwardly directed teeth is arranged on the periphery of the brake ring support, and a second toothed segment with upwardly directed teeth is located opposite the first toothed segment. A support stop engages the slots formed between the teeth of the toothed segments during displacement of the brake ring support. The tooth flanks of the two toothed segments are provided with inclined surfaces in such a way that an upward and downward movement of the brake ring support results in a rotation of the brake ring support by predetermined angle values and an adjustment of the capsule thread brake as a consequence of the support stop abutting against slot bottoms at different axial heights. Several capsule thread brakes may be adjusted simultaneously by a central control device with compressed air pulses supplied by a common compressed air supply line.