| 摘要 |
A braking system for a powered rotary tool of the type in which a shaft is rotated about an axis by a motor, comprises (i) a first brake element mounted for rotation with said shaft; (ii) a second brake element which is restrained from rotation; (iii) resilient means urging said first brake element in an axial direction into braking contact with said second brake element and (iv) means to release the braking contact between said first brake element and said second brake element on start-up of said motor. On start-up of said motor, said shaft is free to rotate through a small angle of rotation before rotation of said first brake element is initiated, and said means for releasing the braking contact on start-up of said motor comprises at least one pair of co-operating ramp surfaces one of said or each pair of ramp surfaces being arranged for rotation with said shaft and said co-operating ramp surface being arranged for rotation with said first brake element. The braking system is particularly suitable for use an a lawn mower of the rotary type. |
