bell crank

from The Century Dictionary.

• noun In machinery, a rectangular lever by which the direction of motion is changed through an angle of 90°, and by which its velocity-ratio and range may be altered at pleasure by making the arms of different lengths.

from the GNU version of the Collaborative International Dictionary of English.

• A lever whose two arms form a right angle, or nearly a right angle, having its fulcrum at the apex of the angle. It is used in bell pulls and in changing the direction of bell wires at angles of rooms, etc., and also in machinery.