Abstract: In a piano normally of a grand piano type, a key action mechanism includes a combination of a fly lever distal end acting on a hammer lever through an intermediate thrust balancing lever, the thrust balancing lever being pivoted at an intermediate portion between proximal and distal ends thereof, and the thrust balancing lever distal end having a change-of-direction roller over which a non-resilient cord is drawn, one end of the cord being connected to an intermediate portion of a wippen lever pivoted at one end thereof, and an opposite end of the cord being connected to a proximate end of a helical spring, and a distal end of the helical spring being connected to an intermediate portion of the fly lever of which the fly lever's lower portion is pivotably mounted on a distal end of the wippen lever, such that when an upward portion of a laterally-extending proximal end of the fly lever is raised to contact an abutment, further raising of the wippen's distal end moves the thrust balancing distal end upwardly a