Action: the internal mechanism of a piano, consisting of several thousand moving parts made from a wide variety of materials
Action Regulation (AKA Regulation): the adjustment of action parts to their proper specifications
Bridge: wooden structure between the strings and soundboard that transmits string vibrations to the soundboard
Centre Pins: different from tuning pins, these are small pins that form the precision pivot point of moving action parts
Damper: a felt cushion attached to a lever assembly that stops the vibration of the strings (the damper pedal lifts this felt cushion so that the strings are able to keep vibrating, creating a sustained effect)
Double Escapement: 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
English Action: each key having a hopper, or jack, that thrusts the hammer onto the string. After the string is struck, the hammer is caught by a check.
Escapement: the mechanism that allows the hammer of a key to fall away from the string after it's struck
Hammer: the mallet that strikes the piano strings to create sound, made of very dense felt wrapped around a wooden core
Key Bushings: felt or leather bushings glued into the keys that enable them to move quietly without clanking when keys are depressed, and return to normal position
Pin lock: the wooden structure that holds the tuning pins in place
Reconditioning: the process of restoring existing parts of a piano and their functions to playing condition
Repetition: a small assembly of wooden levers, springs, felts, and buckskin cushions that is part of the modern grand piano action. There are 88 repetitions in an action – one for each key on the instrument
Restringing: replacing a set of piano strings (inside the body of the instrument)
Soundboard: a large, thin, wooden diaphragm that amplifies the vibrations of the strings
Strings: the steel and copper wires that produce the musical tone in a piano. There are three strings per note throughout most of the piano’s range. These strings are hit by the hammers to create sound.
Tuning: adjusting the tension of the strings to produce desired pitches – tightening or loosening strings to create the desired pitch (a440 on modern concert pianos)
Tuning Pin: the threaded steel shaft that keeps the strings at proper tension and in place at the head of the instrument.
Viennese Action (Prellmechanik): the hammers are hinged so that they are attached to the key levers, and the hammerheads face the keyboard. This kind of action also featured catch and escapement.
Voicing: adjusting the shape, density, and resilience of the individual hammers for desired tonal quality and uniformity throughout the piano