Gages for Internal Diameters - Air Probes

The air probe (also referred to as an air plug gage, air spindle or mandrel) consists of a precision ground hardened steel body incorporating two or more air gage nozzles. Air is passed through the probe body to the nozzles where a back pressure is produced by the surface of the workpiece. An air gage readout (air comparator) senses the resulting back pressure and displays the size of the workpiece.

As shown in the drawing, the nozzle tips are recessed a small amount below the body of the probe. This feature makes the air gage measurement essentially non-contact, consequently wear does not directly affect the accuracy of the gage measurement. Moreover, the flow of air purges the gaging surface of contaminants making the measurements highly reliable.

The air ring has a precision ground hardened steel body with built-in air gage nozzles.

When the ring is slipped over the workpiece, the resulting back pressure is sensed by the air gage readout and displayed as the diameter of the part. Air rings come in 2 and 3-jet configurations. The 3-jet air ring checks for 3-lobe out-of-round conditions prevalent in centerless ground parts that can not be detected with a 2-point gage.

Center-jet style air rings have gaging nozzles in the center of the body; shoulder type have the nozzles near the edge.

Air snap gages offer a convenient way to check crankshaft journals or similar parts.

Western Gage specializes in the design and manufacture of custom dimensional gages, instrumentation, precision components and automated inspection systems.

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