Abstract: A tire pressure detector comprises a hollow cylindrical casing having an internal screw thread for attachment to an inflating valve of a tire. A transverse partition member which divides the casing into two chamber is provided with a projecting pin for pushing the inflating valve to an open position. A cap member is secured to the casing for closing one of the chambers, and a piston member responsive to the pressure is mounted in the chamber. An alarm means is connected to the piston member and has a portion extending out through the cap member. The alarm means may be a graduated rod or an electric light means.

Abstract: 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