Keyboard Resources brought to you by Music Resources USA



keyboard > archives >> how pianos work - grand piano action



All Rights Reserved by K. Wayne Land 1998

NOTE: The above graphic animation and all other graphics on this site were designed and created by K. Wayne Land and as such are the the exclusive property of MusicPlay Piano website. Please respect the immense time and effort put into the creation of these items and refrain from copying and/or redistributing in any way. Of course, links to MusicPlay Piano .html pages are allowed, encouraged, and appreciated.
Purpose of the Action of the Grand Piano

The purpose of the piano action as a whole is to accurately translate every nuance of the player's finger and hand movements into a musical note that reflects the exact intentions of the player. The slightest change in the speed of the stroke, the firmness of the stroke and even the release of the key must result in a corresponding change in the piano's performance. The explanations here will certainly not make you into an expert piano technician but hopefully as a player you will have a better feel for the control of your instrument by grasping the sheer complexity of what happens everytime you press a key down and release it. A piano technician who can make the adjustments necessary to achieve the above described behavior from the piano is indeed a true artisan. Please scroll down to view all the explanations.

Description of Components

The Key itself moves in a "see-saw" type of motion as the player presses the front end. The key coverings of modern pianos are no longer made of Ivory due to legal restrictions on its use. Most manufacturers now offer some variety of a man-made or synthetic ivory to provide a touch sensation that some players feel is conducive to smoother piano technique. Key Leads are used to balance the key's "see-saw" motion so that just the right amount of force is required to press the key down. Since the keys of the piano become longer as you approach the lower notes, lower notes require more key leads than higher notes so as to make all keys feel the same to the player. The key leads must also be positioned very accurately since the closer they are to the front of the key, the easier the key will depress and vice-versa. The Key Button is made of very sturdy wood in order to resist wear from the constant movement of the key on the Balance Rail Pin. The Balance Rail is part of the key frame (not shown) and supports the Balance Rail Bearing which serves as the pivot point for the "see-saw" movement of the key. The vertically adjustable Capstan Screw does the actual pushing up of the other components of the action. The Action Hanger is mounted to the key frame (not shown) and supports three separate rails that each have certain action parts attached to them as you will see below.


The Hammer Flange serves as the support for the hammer which pivots on a Center Pin. The Hammer Flange is secured to the hammer rail with a screw and is held in position by the fluted edges along the rail. This design assures an absolutely stable pivot point for the hammer. The Letoff Screw is screwed into the Regulating Rail and as you can see in the animation above, blocks the bottom half of the jack (shown later) as it moves upward so that it has to pivot out from under the knuckle (shown later).



The Support Flange "supports" a large number of moving parts known as the wippen assembly and is secured to the Support Rail by screw. The three rails mentioned here and above are sometimes made of wood, sometimes extruded aluminum, but the method used here is hollow brass tubing with wooden doweling driven in the center. The brass is considered more durable and has less tendency to add a metallic quality to the piano's tone and the wooden dowel helps to provide better stability for the screws that run through the rail as well as eleminates unwanted metallic resonance.


While most action parts are made of hard maple, the Hammer itself is sometimes made from mahogany or a similar hardwood. It is attached to a Hammer Shank which may be cylindrical or octagonal as shown here. Underneath the hammer shank is attached the Knuckle. It is this Knuckle that is actually pushed up by the jack (shown later). When the jack slips from underneath the Knuckle, the hammer is said to "escape" as it surges upward suddenly and strikes the string. The Hammer Felt, the covering over the hammer, must be of exact hardness and shape to produce the best possible tone when striking the string.


The Wippen Assembly is the most complex part of a piano action and is responsible for the most precise and sensitive control of the motion of the Hammer to and from the string. Both the Balancier and the Jack are responsible for the actual pushing of the Hammer toward the string. The black areas visible above are the carbon coating on the Balancier and Jack in the areas where they push against the Knuckle (shown above). The Hammer "escapes" from the Jack or from the Balancier depending on how the key is moved. Basically if the key is moved from a full stroke the jack does the pushing but if the key is moved from a lower position as in fast or very soft repetition, the balancier does the pushing. This dual pushing of the hammer is called "Double Escapement" and is the single most important innovation in piano action design. The Repetition Spring keeps the balancier in position to be able to perform the above described repetition while the Repetition Felt Block is what the Jack rests against when the Balancier takes over to perform repetition. The Hammer Rest provides a soft landing place for the hammer after it has performed a particularly forceful blow and bounces back all the way down. The Spoon is simply a stop against which the Fly Regulating Screw adjusts the at rest position of the Jack directly against the Knuckle (shown above). The Balancier Covering provides cushioning if the Balancier moves all the way up against the Hammer Flange (shown above) and the Support Cushion provides the curved surface against which the Capstan Screw (shown above) actually pushes up on the entire Wippen Assembly. The Center Pin shown here is the one on which the entire Wippen Assembly pivots as it moves the Hammer.

source: musicplay




about advertise apparel add a site? sitemap broken link? terms privacy contact


2002-2008, MusicResourcesUSA. All Rights Reserved. P. O. Box 2753, Carmichael, CA.  95609

Keyboard Resources