Patent ID: 8336386

Claim:
An air pump pressure gauge for use in an air pump, comprising: a casing shaped like a tube; an inner tube coaxially and fixedly mounted in said casing and defining with said casing an annular accommodation space, said inner tube having one end thereof connectable to an air nozzle assembly of an air pump and an opposite end thereof kept in air communication with an air-pumping passage of the connected air pump and an axial hole defined therein in communication between the two ends thereof; a movable member being an annular member sleeved onto said inner tube within said casing and movable back and forth in said annular accommodation space; a spring member installed in said annular accommodation space and stopped between one end of said annular accommodation space and said movable member to provide a return force to said movable member toward an opposite end wall of said annular accommodation space; at least one seal member mounted on said movable member to define a first airtight structure between the outer surface of said inner tube and said at least one seal member and a second airtight structure between the inside wall of said casing and said at least one seal member; an air hole located on said inner tube between said first airtight structure and the opposite end wall of said annular accommodation space for allowing air to pass from said inner tube into said annular accommodation space to move said movable member; a longitudinal sliding slot located on said movable member; a rack located on said movable member and extending along one side of said longitudinal sliding slot; a rotating axle radially extending through said casing and said annular accommodation space, said rotating axle having an inner end thereof pivotally connected to said inner tube and an outer end thereof extending out of said casing and a middle part thereof fixedly mounted with a gear being meshed with said rack of said movable member so that moving said movable member along the axis of said inner tube causes rotation of said rotating axle forwardly/backwardly; a pointer fixedly connected to the outer end of said rotating axle and suspending outside said casing; a graduation scale mounted on the outside of said casing below said pointer; and a transparent cover fastened to said casing and covered over said graduation scale and said pointer.