Pressure indicator for pneumatic tires
AssigneeDunlop Limited
InventorPhilip H. Pegram
Life of this patent
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Abstract
The invention provides a deflation warning device for a pneumatic tire which gives a clear, positive indication of a predetermined pressure loss by the exposure of a brightly colored element within a transparent dome, all moving parts of the device being fully enclosed and protected against the ingress of dirt and corrosion by a housing. The element is either masked or unmasked by an opaque shield mounted on a piston which is biased by a spring to unmask the element but can be displaced by tire pressure acting on its surface to mask the element. In preferred embodiments of the invention the piston is located between the inner and outer parts of a second piston which is in turn responsive to tire pressure acting on its upper surface.
Claims10
A deflation warning device for a pneumatic tire comprising a housing adapted to be placed in a communication with the air chamber of a pneumatic tire;
- a piston reciprocable in the housing, the piston being biased in one direction and moveable against said bias by tire air pressure;
- a brightly colored visual indicator enclosed within the housing which when is visible therein through a transparent portion of the housing when the piston is in a first position but is masked from view when the piston is in a second position and an annular, opaque mask moveable with the piston to move into or out of said housing portion to mask or unmask the colored element.
A deflation warning device for a pneumatic tire comprising a housing adapted to be placed in communication with the air chamber of a pneumatic tire and two pistons individually reciprocable in the housing, respective biasing means biasing each piston in one direction and means for communicating each piston with tire air pressure whereby it is displaceable against the bias, movement of a first of said pistons producing a visual indication of a predetermined change in tire pressure wherein communication of the said first piston with tire air pressure to displace the same against its bias is controlled by said second piston, said communicating means comprising valve means controlled by the second piston which alternatively communicates the first piston with tire air pressure, when the latter has displaced the second piston against its bias, or with atmosphere when the second piston is moved in said one direction by its bias.
Dependencies are inferred from the claim text.