Abstract: A device for providing an optical indication of the pressure condition in a pressurized member, such as a pneumatic tire. A housing having a window therein carries a reflective surface, such as a mirror, which is mounted on a movable flap. One end of a plunger pin holds the mirror in alignment with the window with the other end of the pin resting on a diaphragm assembly which communicates with the internal pressure of the member. Light from a light source is directed in the window and under normal pressure conditions will be reflected by the mirror. If the internal pressure of the member drops below a predetermined value, the diaphragm will retract dropping the pin thereby moving the mirror out of alignment with the light source. The absence of reflected light is thus indicative of a low pressure condition and corrective measures can be taken.

Abstract: Disclosed is a method and apparatus for measuring stresses in a wire or wire cord, such as that found in the reinforcing belt of a pneumatic tire. A portion of the wire is encapsulated in a solder material which is machined such that a rectangular solid billet of the solder is formed thereon. A transducer or plurality of transducers in the form of strain gauges are fixed to at least one flat surface on the billet and oriented in a direction such that forces applied to the tire will affect the resistance of the transducer. The resistance of the transducer can be balanced in a bridge network and the voltage resulting therefrom suitably readout in terms of the stress being applied to the wire cord. The cord can be built into a tire with the lead wires from the transducer being fed through the tire to the bridge network. The stress tests can then be accomplished in an inflated and running tire.