Lever 1 , turning about fixed axis A , has two projections a. Lever 2, turning about fixed axis B, has projections b. When lever 2 is turned in either direction, one of its projections b contacts the corresponding projection a and causes lever 1 to turn clockwise about its axis A , compressing spring 3 . When lever 2 is released, it will be returned by spring 3 to its initial (central) position.
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