the piano deconstructed

The Action

Explore the Action

Move the mouse over the picture on the right to highlight different components of the action. Click on a highlighted part to learn more about it. Also, be sure to watch the animation of the action in motion, and be sure to try the "action puzzle" - links are located at the left of each page.

The Heart of the Piano

The action is the heart of the piano. Its purpose is to transmit the actions of the pianist to the hammers. The modern grand double escapement action is what allows the grand piano to quickly repeat a note without fully releasing the key. Many piano manufacturers make their own unique modifications to the action. The action images and animations are based on the Yamaha grand double escapement action.

The action mechanism consists of several parts:
• The wippen
• The repetition mechanism
• The jack and let-off button
• The hammer

These parts are activated by the key, and work together to push the hammer toward the string. Each key on the piano controls its own action mechanism – there are usually 88 on the modern grand. The action parts are mounted on rails which are supported by four to five metal action brackets. These brackets are screwed into the top of the keyframe.

Cristofori's original design included a single-escapement action. Single escapement is what allows hammer to be released (escape) from the influence of the key and the rest of the action. The hammer strikes the string and falls back, even if the key is still depressed. Without this escapement, the hammer would be held against the string (muting its vibrations) for as long as the key was depressed. The double escapement action was developed by Sébastien Erard in the 1800's. Double escapement occurs when the jack is reset beneath the hammer as the key is partially released. This allows the note to be repeated quickly without the action parts returning to their original at-rest positions.

Follow the link for a more detailed description of the action...