Video explanation
One key moves linkages and a hammer, showing let-off, rebound checking and damper lift, with a hammer-to-string distance readout.
Lever motion
A sequence of levers transfers key motion to the hammer. Key velocity influences impact velocity.
Let-off frees the string
Near the string, the hammer escapes the driving mechanism, strikes by inertia and rebounds without holding the string down.
Damping and repetition
Key action lifts the damper; release restores damping. Checking and repetition mechanisms control rebound and repeat strikes.