Comprehensive tire pressure differential sensing and indicating device

Claim 1

An improved tire pressure differential sensing device comprising: a housing having at least a partition therein defining a pressure chamber on one side and an adjustably configured closed chamber on the other side, means for connecting a tire valve stem to an opening for said pressure chamber, a transverse passageway in said partition, a sliding piston positioned within said passageway with an end portion thereof extending into said pressure chamber and the other end portion thereof extending into said adjustably configured closed chamber, an axially arranged annular chamber defined by an annular wall portion in the pressure chamber at the side of said partition encompassing the projecting end of said piston, diaphragmatic cap means sealing said annular chamber at the outer end for differential pressure in said pressure chamber urging said cap means into engagement with said piston to move said piston, a flanged means affixed on said other end portion of said piston and a flanged means threadedly engaging an inner wall of said closed chamber, spring means mating at one end with the flanged means of the piston and at the other with the threaded flanged means, a transverse slot in the outer medial face of said piston, and a split contact pin formed of two conductive parts separated along an axial plane thereof by an insulation layer to form portions of two distinct electrical circuits, said split contact pin mounted in an insulating means in the wall of said housing and projecting between the walls defining the slot in said piston for engaging selectively the wall of the slot when the piston is moved to one of the two end positions to close contact between one of the respective conductive parts and the piston.