| 摘要 |
The key shaft is connected to a cylinder-piston activator (1,2) and the key (6) activates a pair of brake shoes (5) by means of power transmission devices, each comprising a pair of telescopically displaceable parts (9-12). One of these parts is an externally threaded rod, whilst the other is an internally threaded socket which receives the rod. One component in each pair has a cylindrical gear crown (18) engaging in radial tracks on an axial stop surface on a wheel located on the key shaft. The track is so shaped that a straight radial movement of the gear crown in relation to the wheel causes a relative torque on the two displaceable parts in a direction producing an increase in their total length. The wheel is axially movable on the key shaft, and is impelled towards the gear crowns by a spring tensioned between it and a fixed part on the key shaft. The other surface area of the wheel is connectable to a snap lock, and runs in the wheel axial direction. |
