| 摘要 |
A pressure gauge (1) for a pneumatic tire (7) includes a casing (10, 10'), a pressure responsive signal-generating device (2) disposed in the casing (10, 10'), an electric power source (3) connected electrically to the signal-generating device (2), and a switch assembly (4) connected electrically to the electric power source (3). The switch assembly (4) includes a normally open reed switch (46, 50), a magnet member (43, 54)) and a magnet support. The reed switch (46, 50) is electrically connected to the electric power source (3). The magnet member (43, 54)) is disposed movably in the casing (10, 10') to produce a magnetic field for activating the reed switch (46, 50) to an ON position, and is movable toward the reed switch (46, 50) via a centrifugal force produced upon rotation of the pneumatic tire (7). The magnet support is disposed adjacent to the reed switch (46, 50) to movably hold the magnet member (43, 54)), and has a biasing unit (40, 53) to provide a biasing action to move the magnet member (43, 54)) away from the reed switch (46, 50) when the centrifugal force is absent. <IMAGE> |
