Chain saw with a tensioning arrangement

The invention concerns a motor powered saw with a saw chain ( 2 ) and a guide bar ( 1 ), the rear portion of which is covered by a side cover ( 3 ) and during operation clamped with a certain clamping force between the side cover and a counter support on that side of the guide bar which is turned towards the motor, tensioning elements being provided for tensioning the saw chain by displacing the guide bar forwards, when the guide bar has been loosened by easing the clamping force, and elements for securing the guide bar in a new position. The characteristic features of the invention are that a rotation element ( 4 ) is mounted or mountable on the exterior of the side cover for easing said clamping force by rotating the rotating element a first angle of rotation; for activating said tensioning elements by continued rotation of the rotation element a further, second angle of rotation, said tensioning elements comprising a guide bar displacer ( 50, 50' ) for displacing the guide bar forwards to anew position for tensioning the chain; and for reclamping the guide bar, but now in the new position, by returning the rotation element to its starting position.