Abstract: A thread pitch cylinder gage for an internally threaded bore in a workpiece, according to one embodiment, includes a gage post having a bearing surface extending through an externally threaded sleeve. The sleeve is trapped on the bearing surface by a retaining cap at the end of the gage post. A finger on the bearing surface engages a notch in the sleeve to prevent rotation of the sleeve relative to the bearing surface, while permitting relative axial motion. The sleeve includes two collections of retaining cavities with balls trapped therein, one at each end of the sleeve. The cavities, and therefore the balls, are centered between the flanks of a thread on the sleeve, and the balls are radially slidable between a retracted and a locked position. The bearing surface includes a plurality of sloped cam surfaces radially aligned with the balls in the sleeve.

Abstract: A thread pitch cylinder gage for an internally threaded bore in a workpiece, according to one embodiment, includes a gage post having a bearing surface extending through an externally threaded sleeve. The sleeve is trapped on the bearing surface by a retaining cap at the end of the gage post. A finger on the bearing surface engages a notch in the sleeve to prevent rotation of the sleeve relative to the bearing surface, while permitting relative axial motion. The sleeve includes two collections of retaining cavities with balls trapped therein, one at each end of the sleeve. The cavities, and therefore the balls, are centered between the flanks of a thread on the sleeve, and the balls are radially slidable between a retracted and a locked position. The bearing surface includes a plurality of sloped cam surfaces radially aligned with the balls in the sleeve.