| 摘要 |
A hammer comprising: a housing 2 ; a motor mounted within the housing; a tool holder 8 rotatably mounted on the housing 2 for holding a cutting tool; a striker 442 mounted in a freely slideable manner within the housing, for repetitively striking an end of a cutting tool when a cutting tool is held by the tool holder 8 , which striker is reciprocatingly driven by the motor, when the motor is activated, via a drive mechanism; wherein the drive mechanism comprises: a pivoting drive arm 457 pivotally mounted within the housing 2 at one end and which is drivingly connected to the striker 442 ; a pivotal drive mechanism connected to the pivoting drive arm 457 which converts a rotary movement generated by the motor to an oscillating pivoting movement of the pivoting drive arm 457 about its pivot point; characterised in that the pivotal drive mechanism comprises a series of wedge shaped ramps 460 which are formed around the circumference of a rotatable shaft 424 wherein the pivoting drive arm 457 is connected via a part which abuts against the rotatable shaft 424 so that, upon rotation of the shaft, the part abuting against the shaft 424 rides over the wedge shaped ramps 460 causing the pivoting drive arm 457 to pivotally oscillate.
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