Parallel motion linkage for the sliding keyboard cover of a piano

摘要

A parallel motion linkage is taught for the sliding keyboard cover of a piano to assure that the sliding keyboard cover, when shifted between its open (key exposing) position and its closed (key covering) position will remain perpendicular to the direction of its motion and will not skew or jam between the sides of the piano case. The structure comprises a pair of bell cranks rotatively mounted to the underside of the sliding keyboard cover near the ends thereof. The bell cranks each have a first short arm, which arms are joined together by a tie rod pivotally connected thereto. The bell cranks each have a long arm to which one end of a connecting rod is pivotally mounted. The free end of each connecting rod is detachably and adjustably affixed to a bracket mounted on its respective side of the piano case.