Action mechanism of an upright piano

摘要

An action mechanism for a upright piano includes a back check mechanism having a back check member provided on the horizontal arm of a hammer arranged to strike a string and a hammer check disposed upright on a wippen constituting an escapement mechanism. With an upright piano incorporating this back check mechanism, it is possible to satisfactorily produce a rapid repetition of a tone with a sound quality approximately that which up until now could only be provided with a grand piano.