| 摘要 |
A power tool, such as a hedgetrimmer, comprising a motor (5), typically electric, a blade set (2, 3) comprising at least one blade (2, 3) driven for reciprocating motion by the motor (5) and a drive train (6) connecting the motor (5) to the blade set (2, 3), the drive train (6) having a coupled state in which motion of the motor (5) is coupled to the blade set (2, 3) and an uncoupled state in which motion of the motor (5) is not coupled to the blade set (2, 3), the drive train (6) being capable of sudden transition from the uncoupled state to the coupled state so as to transfer angular momentum built up in the motor (5) or the drive train (6) to the blade set (2, 3). This allows for a hammer action to be provided to the blades, so that a strong impulse, larger than the force normally exerted by the blade set can be transmitted to the blade set for particularly stubborn obstacles. The drive train may comprise a centrifugal clutch (10), arranged to engage suddenly once the rotational speed of an output shaft (7) of the motor (5) increases above a first threshold and to disengage once the rotational speed of the output shaft (7) drops below a second threshold. |
