The double repetition is possible on the upright piano

[themaximillyan]

The double repetition is possible on the upright piano with using special position of 'the jack of the wippen'' under 'the hammer butt' there.

Working principle:

With an incorrect adjustment of the upright piano action, 'jack of the the upright wippen' under 'the hammer butt' is positioned in such a way that the hammer shank "catches" 'the back check' in the special position.

After striking the string, 'the back check of the upright hammer' must be immediately "caught" by 'the hammer shank' in such a position that 'jack of the the upright wippen' is in an "independent" position and has direct access for a repeated strike to the string. In the classic action adjustment, 'the jack of the wippen' is positioned slightly lower, which does not allow a repeated strike without whole releasing the key here.

In the Sukhopyatkin method, by bending 'the back check wire' of the wippen, a position is achieved in which 'the jack of the upright wippen' is slightly DOWN and allows a repeated strike without releasing the key.

Possible changes:

Changes in the pianist's tactile sensations are possible, but their presence has not been confirmed by statistics.

Double repetition on a piano is truncated and conditional in comparison with a grand piano.

Conclusion:

Double repetition on a piano is possible with a special position of 'the jack' under the upright piano hammer butt, but it differs from double repetition on a grand piano.