the tilting device 4 for a piece of seating furniture the principle here is that the seat plate 1 has a depression 3 this depression 3 is formed in that the seat plate 3 is provided with a circumferentially extending ring 9 the latter can be either monolithic with the seat plate 1 or can also be attached as a separate component to the seat plate 1 it is important in this context that as a tilting device 4 a flat cushion 10 is provided which is positioned within the depression 3 this cushion 10 is filled with a flowable medium for example air water or a gel above the cushion 10 there is also a cover 7 in fig3 a in solid lines the initial situation is illustrated initially when a person seated on the piece of seating furniture moves laterally this forces the flowable medium in the cushion 10 from the corresponding side to the other side of the cushion 10 which is therefore correspondingly bulging this is indicated by the dashed lines when the person then performs a movement in the opposite direction the medium flows back within the cushion 10 fig3 b shows the piece of seating furniture as in fig3 a but with the difference that additionally on the cushion 10 a tilting seat disk 6 is arranged the.