Toilet Tanks With Float Balls
Two types of ballcocks have been around the longest. They are the plunger fill valve and diaphragm type fill valve ballcocks.
The float ball and plunger or diaphragm fill valve or ballcock combination have been used in toilets for many decades. The float ball is hollow and floats on top of the water as it is being filled in the tank. When the water gets to the desired level, the float ball moves the float arm and turns off the water flow in the ballcock. By bending the float arm you can "fine tune" the point at which the water turns off and stops filling the tank.