Abstract: The invention contemplates a pneumatically driven piston as a preloading device, continuously urging the movable part (11) of a probe head into precise seating engagement with its fixed bearing (10), (12) in the housing of the probe head. The piston is movable in a cylinder (4) that is supplied with variable regulated pressure determined by a controlled regulating valve (16). Different contacting forces can be automatically and rapidly adjusted by the control system (18) of a coordinate-measuring machine to which the probe head is mounted, and the probe head can be tared to compensate for the different individual weights of successively different probe pins that are used in a given program of multiple-point coordinate measurements on a workpiece.

Abstract: To overcome friction in the mount of the switching-type probe head, a probe (5/6) displaceably mounted therein is transiently excited in oscillation for a predetermined time after each contacting process. The same piezoelectric element (17) as that which produces the initial work-contact signal in the probe head can additionally be used to stimulate the oscillations.

Abstract: For a horizontal orientation of a switching-type probe head, force developing device is provided to compensate for a component (F.sub.1) of the gravitational weight vector (F.sub.g) of the deflectably movable part (11) of the probe head, the compensating force being perpendicular to the direction of loading the movable part (11) into its at-rest (undeflected) null position in the probe head. This force-developing device is illustratively a magnetic bearing (5, 6) which is operative without involving any added mechanically contacting action within the probe head.

Abstract: Truncated pyramid mounting configurations and relationships are disclosed as inherently and reproducibly determining an accurate zero-position as between a probe head and a probe pin that is deflectably carried by the probe head. And the same principle of accurately determining zero position is also described in application to the automated releasable chucking of interchangeable probe pins and/or of an auxiliary probe head, as to the installed probe head of a coordinate-measuring machine.In one described case of truncated triangular pyramid mountings, the zero position is determined by concurrent engagement of six seating points which are distributed radially and axially with respect to the common central longitudinal axis of the involved geometric pyramids.The mounting configurations have high torsional rigidity and a relatively large region within which self-centering to the zero position is achieved.