Patent ID: 7231821

Claim:
A system for actuating an indicator assembly in response to a depth change in a liquid that is confined to a container, comprising: an elongate housing; a float constrained to vertical movement lengthwise in the housing in response to changes in liquid depth in the container; a drive rod extending through the float and arranged to rotate in response to vertical movement of the float; an indicator assembly arranged to indicate the position of the float in the housing, thereby indicating liquid depth in the container; a magnetic coupler mechanism arranged to transfer movement of the drive to the indicator assembly, the magnetic coupler assembly including: a first dielectric disc connected to the drive rod, the first dielectric disc having three magnets mounted thereon with their poles facing upwards; a second dielectric disc connected to the indicator assembly, the second dielectric disc having three magnets mounted thereon with their poles facing downwards such that opposite poles mounted on the first and second dielectric discs are arranged with opposite poles in facing relationship such that magnetic forces transfer rotation of the drive rod to the indicator assembly wherein the three magnets on the first dielectric disc are arranged so that two North poles and one South pole facing upwards and the three magnets on the second dielectric disc are arranged so that one North pole and two South poles are facing downward and wherein the elongate housing is formed as a tubular frame that includes a pair of diametrically opposed 270° rifling grooves and wherein the float includes a pair of projections arranged so that each one of the pair of projections extends into a corresponding one of the 270° rifling grooves.