| 摘要 |
A pressure gauge includes a housing, an indicating board, a rotatable axle with a pinion member, an indicator for displaying the degree of rotation of the axle, a tube member disposed on the housing and having an air inlet, a movable member sealingly disposed in the tube member near the air inlet for being forced by the external air pressure to move, a compression spring for biasing the movable member toward the air inlet, a rack member movably mounted in the tube member and capable of extending outwardly of the tube member in the housing to mesh with the pinion member so as to drive the axle to rotate, a tension spring for pulling the rack member toward the movable member, a blocking member normally brought into engagement with the surface of the axle to create a friction force therebetween when the axle is driven to rotate by the rack member as the movable member is forced downwardly by the air pressure, wherein the friction force is adjusted higher than tension force of the tension spring when the tension spring is at its most tensed state; thereby, only when the blocking member is released from the axle, will the rack member be pulled by the tension spring to its original position.
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