| 摘要 |
A brake device acting directly or indirectly on a drum (1) so as to automatically brake the drum in the event that a certain speed of the drum (1) is exceeded. The braking device comprises a gear (9, 10, 11, 12, 16) driven by and gearing up the speed of the drum (1), which gear in turn is arranged to rotate a brake body (4) rotatably suspended in its one end (6) with an inherent weight adapted to the said speed. The brake body (4) is pretensed by means of, for example, a spring (5) or the like adapted to the said inherent weight and said speed to be kept from braking via direct or indirect contact with the drum (1), at a speed that is lower than said speed and that is unable at a speed that is higher than the said speed to prevent the brake body (4) through the centrifugal force exercised on account of rotation from making direct or indirect contact with the drum (1) and thus braking the same. The drive force which is arranged by the gear (9, 10, 11, 12) to be applied to the brake body (4) is applied to the brake body (4) via an actuating member (13, 16 and 18, respectively) working between the gear (9-12) and the brake body (4) which is so elaborated that when the brake body (4) directly or indirectly contacts the drum (1) a servo effect is caused to begin to act, which is arranged to increase the braking action of the brake body (4). |
