Driving device for a hardness measuring instrument

Abstract

A driving device for a hardness measuring instrument of the type including a fixed structure (2,3,4,5,6) having a base on which a piece to be controlled is firmly resting, and a movable assembly (7,8,9,10) that is driven from a motor (6) during a measuring cycle in such a manner as to be initially brought nearer the piece to be controlled and subsequently subjected to a measuring load, wherein the device utilizes, between the motor (6) and the movable assembly (7,8,9,10), two coaxial screws (11,13) having equally running threads, one of which screws is a large-pitch screw (11) and the other one is a small-pitch screw (13), the two screws being driven from the motor (6) and being arranged so that during a measuring operation, first the large-pitch screw (11) acts to cause the movable assembly (7,8,9,10) to be rapidly moved towards the piece to be controlled and then the small-pitch screw (13) acts to cause said movable assembly to be brought nearer said piece by a slow powerful motion, the reverse procedure taking place for returning the instrument (10) to its starting position.

Dependencies are inferred from the claim text.