| 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 (114) mounted for rotation with the shaft (106); (ii) a second brake element (136) which is restrained from rotation; (iii) resilient means (144) urging the first brake element (114) in an axial direction into braking contact with the second brake element (136) and (iv) means to release the braking contact between the first brake element (114) and the second brake element (136) on start-up of the motor. On start-up of the motor (104), the shaft (106) is free to rotate through a small angle of rotation before rotation of the first brake element (114) is initiated, and the means for releasing the braking contact on start-up of the motor (104) comprises at least one pair of co-operating ramp surfaces (126, 132), one (126) of the or each pair of ramp surfaces being arranged for rotation with the shaft (106) and the co-operating ramp surface (132) being arranged for rotation with the first brake element (114). The braking system is particularly suitable for use on a lawn mower of the rotary type. <IMAGE> |
