Water-saving cistern for water closet pan

The utility model discloses a water tank of a water-saved toilet seat, comprising a large water tank with a water outlet, a control water tank with a communicating hole, a casing which is provided with a water inlet and a guide bushing, a slide bar which is provided with a sealing block on the bottom portion, a main shaft, a rotary table, the inner side of the rotary table is provided with a roller shaft and a projection, the roller shaft is provided with a roller, a muffle with a handle, a disk drive with an annular flange, a slave disk with a crank, the bottom end of the crank is screwed with a bolt with a plug, a rotating key clutch is arranged between the disk drive and the slave disk, a rotating key seat, one end of the rotating key seat is connected with the roller, a draught spring, a balance wheel with an oscillating arm, a rolling wheel which is connected with a floating bucket via a connecting device, the rear end of the oscillating arm is connected with the top end of the slide bar via a steel chain, and an oscillating frame wheel which is provided with an oscillating frame, one end of the oscillating frame is extended with a horizontal flange, and the oscillating frame wheel is sleeved with a torsion spring. The water tank of a water-saved toilet seat of the utility model can effectively save water.