Tire pressure detector

A pressure detector for a tire having an inflating valve comprising:

• a hollow cylindrical casing having a transverse partition member dividing said casing into a first and a second chamber, and a passageway communicating with said first and second chambers, the wall of said casing having an internal screw thread in said first chamber for attachment to said inflating valve, said partition member having a pin member projecting therefrom into said first chamber for pushing said inflating valve to an open position;
• a cap member secured to said casing for closing said second chamber;
• an inside tube inserted in said second chamber and having first conduit-defining means for establishing fluid communication between the second chamber and the portion of the tube near the cap member;
• a piston member mounted in the inside tube for reciprocating movement in response to the pressure in said second chamber;
• second conduit means for establishing fluid communication between said first chamber and said second chamber;
• alarm means positioned to be connected to said piston member when the pressure in the second chamber is not more than a preselected level, and having a portion extending out through said cap member;
• and
• biasing means for disconnecting the piston from the alarm means when the pressure in the second chamber is more than the preselected level.