Escapement

A mechanism in a piano that allows the hammer to fall away from the string after the key is pressed. After a key on the keyboard is depressed, an instant before the hammer strikes the strings, it “escapes” its connection to the key so that it can strike the strings and then fall away from it, allowing the strings to continue to vibrate. Digital and controller keyboards with “piano action” use weights and other methods to simulate this behavior in acoustic pianos.