| 摘要 |
This invention relates to an arm preferably for electric switches the arm being controlled by electricity and having a first fixed end and the other end of which is movable mainly perpendicular to the length direction of the arm. The arm comprises two mainly parallel parts (47) separated by an air gap (17) or some other heat insulating material and which are secured to each other at each end. At least one of the parts can be heated by electricity and through longitudinal heat expansion with respect to the other part achieve said movement. The parts are so shaped that they adjacent the fixed end (at 45) with respect to the rest of the parts have a reduced bending resistance about an axis which is perpendicular to the length direction of the arm and with respect to said direction of movement. |
