| 摘要 |
A pressure gauge includes a housing unit and a membrane which has a periphery secured to an inner wall of the housing unit, so as to define an air chamber under the membrane in the housing unit. The membrane has a central portion which can move upward in the housing unit in response to increase in air pressure of the air chamber. An adjustment rod has an externally threaded portion extending through and engaged threadably within the threaded hole of a guiding member which is secured in the housing unit. A microswitch is installed on a lower end portion of the adjustment rod and is connected electrically to a pressure source which supplies compressed air into an article to be measured by the gauge. The movement of the adjustment rod relative to the guiding member moves the microswitch in the housing unit to a predetermined position which corresponds to a preset upper limit value of air pressure of the air chamber. When the air pressure of the air chamber exceeds the preset upper limit value, the microswitch is contacted and activated by the central portion of the membrane to stop supply of compressed air from the pressure source into the article.
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