Abstract: A portable chain saw wherein the motor drives a hub which is coaxial with a cylindrical portion of the shaft for one sprocket wheel of the chain. A coil spring is wound around the hub and the cylindrical portion to normally transmit torque from the hub to the shaft and to brake the shaft in response to its disengagement from the hub as a result of pivoting of a guard for one hand of the operator. The guard is pivoted by the one hand when the chain saw wobbles or performs other undesirable movements. The coil spring, the hub and the cylindrical portion together constitute a so-called wrap spring clutch wherein the spring rotates with the hub until arrested by a pin-shaped decoupling element which is movable radially of the hub by a second spring in response to pivoting of the guard.

Abstract: A hedge cutting arrangement has a cutting device, a drive motor for driving the cutting device, a coupling arranged between the cutting device and the drive motor, two handles for two-hand operation, and two switching devices including actuating members, wherein the coupling is connected with both actuating members so that even when only one of the actuating members moves to its switching off position, the cutting device disconnects from the drive motor.

Abstract: A switch includes an actuating element movable against a biasing force from a rest into a working position. The element is engageable with a member movable under a force of a predetermined magnitude applied thereto between a first position corresponding to the rest position of the element and a second position in which it displaces the element into the working position. The member is provided with a spring for urging the member against the applied force into the first position so as to release the actuating element. The member tends to prematurely move into the first position in response to a slight decrease of the applied force to a lever below the predetermined magnitude. The switch is further provided with an arrangement for preventing the premature movement of the member into the first position until after the applied force decreases below the above-mentioned level.