Abstract: An electric power tool of the type which has an inserted tool bit (8), which can be operated with a rotary and a hammer action, and comprises a hammer which can be activated by axial displacement of the tool bit (8) by engagement with the work piece, also comprises a manually operable adjustment handle which can be rotated about an adjustment axis (59) between a first position in which a stop element (53) permits the axial displacement for the activation of the hammer, and a second position in which the stop element (53) blocks the axial displacement. The stop element (53) is connected with cam surface (61, 62) which is coupled with an adjustment element (41) movement of which switches between high and low speeds of the tool. The cam surface has an arc-shaped portion (61) circular about the adjustment axis (59). Connected to one end of the arc-shaped portion (61) of the cam surface is a curved second portion (62), the distance of which from the adjustment axis (59) changes continuously.

Abstract: A device for cutting vegetation has a housing rotatable about an axis, a rotatable spool within the housing storing a supply of flexible line having an end extending through an aperture in the housing into a cutting plane normal to the axis, and an arrangement for automatically letting out additional line by causing relative rotation between the spool and housing whenever the length of line extending into the cutting plane is less than a predetermined length. The automatic arrangement includes a series of angularly-spaced locking faces provided on the spool (or on a member connected thereto) or on the housing, and a balance bar pivotally mounted on the housing or on the spool with this balance bar having a member for engagement with the locking faces. The center of gravity of the balance bar is on the side of the pivot point opposite from the engagement member. In use, the balance of forces on the engagement member directs this member against the locking faces.