Abstract: A flush valve for a toilet having a tank and a bowl including a valve housing connected to a source of water, a valve stem operatively connected to a float and a piston operatively connected through a cam to a flush lever, the valve stem and piston movable independently to provide a valve for the admission of water to the tank and bowl together with a syphon having a tube therein for breaking the syphon action at a predetermined level of water in the tank, a float operatively connected to the valve stem which automatically varies the float level action and an arm connected to the cam for actuation by the float to return the flush lever to an inoperative position and another valve operated by the piston to interrupt the flow of water into the valve housing to prevent back syphonage of tank water into the water supply line.

Abstract: Disclosed herein is a ballcock type flush valve that has all moving parts above the water line of the tank, thereby eliminating corrosion. The valve configuration is such that it is designed to shut-off the flow of water, thereby providing a positive shut-off, and further it is unique in that it has no seat or seal to leak that is below the water line. Fail safe features include a flush mechanism that will remain inoperative until the tank has regenerated its water supply, thereby providing a full flush. Anti-syphon means are included in addition to prevent back flow of bowl water into the water system. The ballcock flush valve combination is so constructed that ingress of additional water due to a faulty seal is impossible thereby conserving water.