Flushing mechanism intended to be mounted on a toilet tank, comprising: - a hollow body intended to be fixed on a lid of the tank; - at least one push-button mounted height adjustable in the hollow body between an idle position and at least one pressed position; - a frame intended to be mounted inside the tank and comprising a sealing means mobile between a sealing position and a releasing position of an orifice for the passage of water arranged in a bottom of the tank; - a transmission mechanism between the push-button or push-buttons and the sealing means, comprising: - a traction rod coupled to the sealing means, the traction rod extending through a lower passage of the hollow body and being mobile in height along a translation axis T with respect to the hollow body; - a shuttle lever system housed in the hollow body, the shuttle lever system comprising a lever mobile in rotation about an axis of rotation R making it possible to invert the displacement in height of the push-button or push-buttons with respect to that of the traction rod; - means for blocking in height the traction rod with respect to the hollow body, - the lever occupying a blocking position in height of the traction rod in the idle position of the push-button or push-buttons, the push-button or push-buttons being coupled to the lever in order to drive the rotation of the lever and, during an actuating of the push-button or push-buttons, release it from its blocking position, the flushing mechanism characterised in that the lever has a toothed wheel centred on the axis of rotation R, the toothed wheel being meshed on a rack carried by the or one of the push-buttons. - a hollow body intended to be fixed on a lid of the tank; - at least one push-button mounted height adjustable in the hollow body between an idle position and at least one pressed position; - a frame intended to be mounted inside the tank and comprising a sealing means mobile between a sealing position and a releasing position of an orifice for the passage of water arranged in a bottom of the tank; - a transmission mechanism between the push-button or push-buttons and the sealing means, comprising: - a traction rod coupled to the sealing means, the traction rod extending through a lower passage of the hollow body and being mobile in height along a translation axis T with respect to the hollow body; - a shuttle lever system housed in the hollow body, the shuttle lever system comprising a lever mobile in rotation about an axis of rotation R making it possible to invert the displacement in height of the push-button or push-buttons with respect to that of the traction rod; - a traction rod coupled to the sealing means, the traction rod extending through a lower passage of the hollow body and being mobile in height along a translation axis T with respect to the hollow body; - a shuttle lever system housed in the hollow body, the shuttle lever system comprising a lever mobile in rotation about an axis of rotation R making it possible to invert the displacement in height of the push-button or push-buttons with respect to that of the traction rod; - means for blocking in height the traction rod with respect to the hollow body, - the lever occupying a blocking position in height of the traction rod in the idle position of the push-button or push-buttons, the push-button or push-buttons being coupled to the lever in order to drive the rotation of the lever and, during an actuating of the push-button or push-buttons, release it from its blocking position, the flushing mechanism characterised in that the lever has a toothed wheel centred on the axis of rotation R, the toothed wheel being meshed on a rack carried by the or one of the push-buttons.