Abstract: A reference-load variable hardness tester for measuring Rockwell hardness and Rockwell superficial hardness, having an internal coil spring and an external coil spring disposed coaxially with a load shaft for each reference-load. When measuring Rockwell hardness, both the internal coil spring and the external coil spring work for the reference-load, and when measuring Rockwell superficial hardness, only the internal coil spring works for the reference-load.

Abstract: An apparatus for positioning a loading shaft of hardness tester prior to application of test load. A loading shaft position detector is provided for detecting the arrival of the loading shaft at a given position when elevating it, and the detector controls an electromagnetic means to check further continuation of the elevating operation of the loading shaft so that the loading shaft is set automatically at the given position. An electromagnetic clutch or brake serves as the electromagnetic means.

Abstract: A hardness tester for measuring hardness of a material by pressing an indenter attached to the lower end of a load application shaft into the test specimen. A reference cylinder is coaxially and slidably fitted around the load application shaft, and a datum plane, to be in contact with the specimen, is formed at the lower end of the reference cylinder, so as to limit the penetration depth of the indenter into the specimen to a predetermined constant depth. A stop device is provided for regulating the descending of the load application shaft relative to the reference cylinder. A load detector for hardness measurement is interposed on the load application shaft, to measure the hardness of the specimen by measuring the force applied to produce an indentation of a predetermined size on it.

Abstract: A shock-absorbing mechanism for use in a dial gage where longitudinal motion of the spindle is converted to rotational motion of a pointer shaft gear by a pinion shaft rotated by said spindle and a magnifying gear coaxially and idlingly meshed with said pinion shaft, comprising a star-shaped pressure spring with radiately extending, elastic branches having not only elasticity in the axial direction of said pinion shaft but also high rigidity in the rotating direction thereof, and a dished spring bearing to deform said pressure spring so as to provide said axial elasticity, said star-shaped pressure spring and dished spring bearing being disposed coaxially with said magnifying gear and a stopper ring fixed on said pinion shaft so that the magnifying gear is pressed against the stopper ring in a frictionally contacted manner.

Abstract: A Rockwell hardness tester having a load application mechanism having a load transfer unit divided into an upper transfer member and a lower transfer member having bores through which an indenter shaft of the tester extends axially with some play. The transfer members are disposed coaxially and have a pair of balls therebetween horizontally arranged in a direction perpendicular to a knife edge on an upper end of the upper transfer member supporting a load application lever. The load transfer unit rests on a spring support cylinder with an initial load spring circumferentially thereof and having its lower convolutions resting on the expanded portion of the indenter shaft and the load applied to the tester is accordingly never applied eccentrically to the indenter shaft.