| 摘要 |
The device disclosed has an extendable resetting member arranged between the brake cylinder and the mechanical actuating device with two (14, 20) resetting elements interconnected by means of a non-selflocking screwthread (18). The aim of the invention is to propose a measure which precludes undesired resetting if the foot brake is actuated when the hand brake is on. According to a first solution, the other resetting element is mounted not rotatably, but elastically and axially mobile with respect to the brake piston in such a way that the resetting device, which is locked by actuation of the hand brake, also remains locked during a long piston stroke, because the other resetting element is held at an axial distance from the piston but engaged with the piston in the normal condition when the spring (82) is not applied. According to a second solution, the resetting device is provided with a stepped piston (135), which prevents resetting only in the event of high hydraulic pressure. According to a third solution, one of the resetting elements is provided with a floating bearing (246-285), by means of which it can be displaced in the longitudinal direction of the brake cylinder after an appropriate frictional force is overcome. |
