| 摘要 |
A tire pressure indicator includes a cylindrical housing having an axial bore communicating with the interior of a pneumatic tire either through the tire valve stem or directly through the wheel rim. A valve poppet is movable within the housing between a first position in which it seals the tire by engaging a shoulder projecting inwardly in the bore and a second position in which it is spaced from the shoulder to release air from the tire. A hollow cap threadedly connects to the housing and, when so connected, compresses a spring in the housing that biases the poppet toward its second, releasing position against the air pressure in the tire biasing the poppet toward its first, sealing position. When the pressure in the tire drops to a predetermined level, the poppet moves to its second position releasing air into the cap. An indicating element normally concealed within the cap is projected from the cap by the released air to provide a visual warning of the tire pressure drop. An improved poppet and indicating element design and improved arrangement of seals prevent the leakage of air through the indicator and seal the indicator against the influx of foreign materials therein. |
