Abstract: A power cutter is disclosed whose dust suction-discharge fan is driven to rotate at a high speed to thereby attain sufficient dust suction-discharge performance, and which can be constructed relatively compactly in size as a whole at a reduced cost. The power cutter includes two rotating operative components (30, 50) driven by a prime mover (5) and a centrifugal clutch (10) operatively connected to the output shaft (7) of the prime mover (5) for rotationally driving the two rotating operative components (30, 50). The centrifugal clutch (10) includes a clutch drum (11) composed integrally of a small diameter pulley portion (21) and a large diameter pulley portion (22). Belt-type drive trains (15A, 16A and 17A, 18A) transmit the rotational drive force to the rotating operative components (30, 50), respectively.

Abstract: A power cutter is disclosed which is capable of selectively changing the discharge direction of dust discharged from a dust discharge port of a dust suction-discharge fan and, hence, which is capable of optimally adjusting the dust discharge direction according to the operational condition or operational position of the power cutter. An elbow-shaped auxiliary discharge pipe is coupled to the dust discharge port of the dust suction-discharge fan in such a manner that it can be turned and kept at any turned position. In addition, a belt tensioning clutch is provided to permit selective connection and disconnection of the belt drive transmission between the power source and the dust section-discharge fan. This permits fan operation to be interrupted when not needed.

Abstract: A portable power tool includes a power module and a tool module, e.g., a chain saw module which is attached to the power module and which can be readily exchanged with another tool module, e.g., a cutter module. The power module includes a power source such as two-stroke gasoline engine with a drive shaft. To facilitate rapid exchange of tool modules, there are two or more torque transmission members such as a pulley and a sprocket wheel on the drive shaft, so that different tool modules can be attached to the power module without removal and replacement of the torque transmission member.

Abstract: The present invention provides a driving force transmission device (P) which is adapted so that the distance (Ls) between the driving force transmission wheels such as a pair of pulleys (16,32) can readily and surely be changed, thereby, making it possible to constantly exert an appropriate tension on a driving force transmission member such as a belt (22), even without a tension roller. The driving force transmission device (P) includes: a first driving force transmission wheel (16) which is driven to rotate, a second driving force transmission wheel (32), an endless driving force transmission member (22) mounted around both the first driving force transmission wheel (16) and the second driving force transmission wheel (32) for transmitting driving force therebetween, and an eccentric shaft (40) which has a pivotal axis (O) at a position eccentric to an axis (Cb) of the second driving force transmission wheel (32) and on which the second driving force transmission wheel (32) is rotatably mounted.