A tire pressure gauge comprising:
- a housing in which an open accommodating chamber is defined, the open accommodating chamber having a groove defined around an outer rim thereof relative to the housing and communicating therewith, wherein the open accommodating chamber also has a pressure measuring unit disposed therein, and the pressure measuring unit has an air guiding device opposite to the housing, the pressure measuring unit further has a numerical display panel mounted on one end surface thereof relative to the housing, and the numerical display panel has a tire pressure displaying area and a tire-tread depth displaying area, wherein the tire-tread depth displaying area is circular to display a tire-tread depth in a clockwise direction;
- the groove of the housing has a plurality of first orifices defined on two sides thereof, and the housing further includes a through hole formed on a predetermined position thereof relative to the plurality of first orifices;
- the groove of the housing also has a tire-tread depth measuring unit fixed thereon, wherein the tire-tread depth measuring unit contains:
- a mounting assembly including a holder, a seat secured on a central position thereof, a first aperture defined on one surface of the seat, a second aperture and a third aperture which are defined above the first aperture, a vertical slot formed aside the second aperture, a fourth aperture defined in the vertical slot relative to the holder, a fifth aperture arranged on a predetermined position of one side of the vertical slot, and two locking recesses defined aside two sides of a top end of the vertical slot;
- a gear assembly including a first gear, a second gear, a third gear, a fourth gear, a fixing plate, a driving member, a hair spring and a transmission shaft, wherein the second gear has a first opening, the fixing plate has a second opening corresponding to the first opening, such that a first end surface of the first opening aligns with the second opening, and a second end surface of the first opening is alignment with the third aperture of the mounting assembly, the third gear has a first connection portion and a second connection portion which extend outwardly from two end surfaces of the third gear, wherein the second aperture of the mounting assembly corresponds to the first connection portion, such that the first connection portion is coupled with the second aperture, and the fixing plate further has a third opening corresponding to the second connection portion, such that the second connection portion is joined with the third opening, and the second gear meshes with the third gear, the first gear has a fourth opening defined thereon, such that the fourth opening aligns with the second opening of the fixing plate, and the first gear meshes with the fourth gear, wherein the fourth gear has a third connection portion extending outwardly from one end surface thereof, and the hair spring is in a spiral shape, the hair spring has a first joining segment formed adjacent to a central position thereof, such that the first joining segment aligns with the third aperture of the mounting assembly, and the hair spring also has a second joining segment extending outwardly opposite to the first joining segment to connect at a predetermined position of a back surface of the mounting assembly, the driving member has a first pore formed on a central position thereof to align with the first joining segment of the hair spring, and the transmission shaft inserts through the fourth opening of the first gear, the second opening of the fixing plate, the third aperture of the mounting assembly, the first joining segment of the hair spring, and the first pore of the driving member, such that a distal end of the transmission shaft abuts against and connects with the first gear, the fixing plate, the second gear, the hair spring, and the driving member, hence the first gear, the fixing plate, the second gear, the hair spring, and the driving member are driven by the transmission shaft simultaneously;
- the third connection portion of the fourth gear has an indication portion arranged on a central position of an outer edge thereof and fixed in the tire-tread depth displaying area of the numerical display panel;
- a damping washer mounted in the fifth aperture of the mounting assembly by inserting a first screw in the fifth aperture of the mounting assembly;
- a longitudinal post vertically connected with the vertical slot of the mounting assembly and including a slidable rack arranged on a top end thereof, such that the slidable rack extends out of the through hole of the housing, the longitudinal post also including a flat portion formed on a predetermined zone of a front end surface thereof, and the flat portion having a meshing rack fixed on one side thereof to correspond to the third gear, such that the meshing rack meshes with the third gear, and the longitudinal post further including a measurement stem secured on a distal end thereof and downwardly extending out of the fourth aperture of the mounting assembly;
- and
- a covering lid including a first ventilation aligning with the fixing plate and the first aperture of the mounting assembly, wherein a second screw is inserted through the first ventilation to screw with the first aperture of the mounting assembly, and the covering lid also including a second ventilation defined thereon to correspond to the third connection portion of the fourth gear, such that the third connection portion of the fourth gear is connected with the second ventilation of the covering lid, and the covering lid further including two tenons formed thereon to correspond to the two locking recesses of the mounting assembly.