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Tire pressure alarm

  • US 4,263,579 A
  • Filed: 11/15/1979
  • Issued: 04/21/1981
  • Est. Priority Date: 11/15/1979
  • Status: Expired due to Term
First Claim
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1. A tire pressure alarm system for a vehicle having a frame with an operator compartment and mounted on wheels with inflatable tires and having an electrical storage battery comprising:

  • a compact transmitter including a low pressure responsive, fixed frequency radio signal generator with a nominal input power less than 100 milliwatts, an electrical battery for said transmitter and magnetically actuable switch closure contacts located between said signal generator and said transmitter battery, all positioned on a vehicle wheel and having enabling electrical contacts in circuit and operable by an air pressure check valve of a vehicle tire mounted on said wheel, and rotatable with said wheel relative to the frame of said vehicle,a receiver secured to said vehicle frame proximate to said wheel and including;

    an electromagnetic element for closing said magnetically actuable switch closure contacts only when said transmitter is rotated with said wheel into proximity therewith, and a radio frequency diode detector tuned to said radio frequency signal generator,an alarm located in the cab of said vehicle with a wired connection to said receiver, anda power connection leading from said vehicle electrical storage battery to said electromagnetic element and including a normally open disabling switch therein which is closed by a mechanism associated with vehicle operation.

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