Switchable and adjustable thread tensioner

摘要

The first brake disc (2) is arranged on a first shaft (6) which has an operative connection (7, 8) with a driving device. The second brake disc (3) is arranged on a second shaft (11) designed as a hollow shaft. A gear (12) located outside the brake discs (2, 3) connects the two shafts (6, 11) to one another. The braking force is adjustable by means of a pressure element consisting of an air-filled concertina (70) which is connected to a central controllable pressure-holding device (72). The second brake disc (3) is mounted axially movably. Located in the hollow shaft (11) is a slide (73) which makes the operative connection between the concertina (70) and the brake disc (3). The adjustment of the braking force is thereby improved and made easier, thus guaranteeing, in particular, the proper operation of thread tensioners running in parallel. <IMAGE>