Pivotable two-coordinate scanning head with horizontal main axis

A pivotable two-coordinate scanning head with a horizontal main axis for measuring gears and gearlike workpieces on numerically controlled measuring devices comprising first and second superimposed straight guides, with which a feeler can be deflected in both a first coordinate direction and in a second coordinate direction perpendicular to said first direction, with the first straight guide providing the deflection in the first coordinate direction which also coincides with the main axis, and further including a pivot mechanism which rotates the first and second straight guides into predeterminable angular positions around the main axis and a weight balance set-up for the first and second guides, characterized in that;

• a) the first superimposed straight guide consists of a linear slide with roller bearing for providing the deflection in the first coordinate direction and the second superimposed straight guide consists of a parallelogram system including a first member, a base, a second member and a coupling member with leaf spring joints for providing the deflection in the second coordinate direction;
• b) the linear slide including a two dimensional ruled grating scale mounted thereon for the two coordinate directions, said scale being read simultaneously by two read heads located on the base of the parallelogram system;
• c) a first mechanical device is provided which holds the linear slide in a definite central position from which the feeler can be deflected with an equal measuring force in both positive and negative directions along the first coordinate direction;
• d) a second mechanical device is provided which holds the parallelogram system in a central position defined by the main axis, from which the feeler can be deflected with an equal measuring force in both positive and negative directions along the second coordinate direction;
• e) the weight balance set up including a roller bearing coaxial with respect to the main axis provided on the coupling member of the parallelogram system and suspended by two tension springs mounted diametrically on an outer ring of the roller bearing and extending from a fixed housing part.