Abstract: An upright piano type action has a wippen 30, a jack 40, a butt 5, a swinging shank (hammer shank 71), a swinging member (hammer 70), a catcher shank 53, a backcheck 60 and a catcher 52. To any of the moving members, namely the butt 5, the swinging shank (hammer shank 71), the swinging member (hammer 70), the catcher 52 and the catcher shank 53, a weight 110, 120, 130 or 140 is attached. The weights 110, 120, 130, 140 are placed to apply loads, respectively, in a state where a key is not being depressed, in a direction opposite to a direction in which the moving members swing for hitting.

Abstract: A surface 60 of a butt 50 has a flat portion 61 which is situated forward and has a small inclination angle and a slanting pressure receiving portion 62 which is situated backward and has a large inclination angle as areas pushed up by a jack 40. Between the flat portion 61 and the slanting pressure receiving portion 62, an escapement portion 63 having an obtuse angle is formed. The escapement portion 63 is provided to correspond to a position of the jack 40 placed immediately after the start of swinging of the jack 40. The inclination angle of the slanting pressure receiving portion 62 is determined such that in a stage where a key starts returning from a slow full stroke key-depression, a position at which the butt 50 is in contact with the jack 40 is maintained with the butt 50 swinging backward.

Abstract: A jack motion-restricting device for an upright piano, which is capable of maintaining constant a jack motion-restricting position by a simple construction to thereby obtain an intended operation of the jack. The jack motion-restricting device restricts the motion of the jack operating in accordance with key depression by having the jack abut thereagainst. A base part of the device is provided at a location close to the jack. A base layer of the same is formed of a material having dimensional stability, and is affixed to the base part. A surface layer of the same is formed of a material having abrasion resistance and flexibility, and is affixed to the base layer, for having the jack abut thereagainst.

Abstract: A universal piano action having a minimum number of identical parts interchangeable in upright and grand pianos, under and above the tensioned strings and effecting rapid repetition in upright and grand pianos, this universal piano action responds to every strenght of touch evoking sounds from a whisper to thunder. In this universal piano action the hammers can be positioned to any at rest position, to any proximity in respect to the tensioned strings for a sensitive control of sound, permitting practice playing with a normal strenght of piano key touch without disturbing.

Abstract: A piano keyboard apparatus has an action assembly that includes a four bar linkage having four pivotably connected bars including a whippen pivotably connected to a repetition lever. An articulated jack has a lower link pivotably connected to an upper link and the lower link is pivotably connected to the whippen.