SCRATCH STRAIN RECORDER

摘要

A scratch strain gauge has an annular target guided into its recording position where it cooperates with a scratch element on a scratch arm to indicate strains of opposite senses. The gauge has a guide adjacent one edge of a plate on which rollers are mounted for rotatably mounting the target in cooperation with brushes. The guide cooperates with a groove in the periphery of the target to insure that the groove receives one of the rollers, then the brushes, and finally the other roller as the target is inserted into its recording position. Ears, which are disposed above the rollers and extend outwardly beyond the rollers to overlie portions of the target when the target is in its recording position, aid in insuring that the target is seated on the roller tongues when disposed in its recording position.