The invention relates to testing apparatus and respective control circuit means, especially for testing samples including movable elements such as vehicular axles with the respective wheels wherein load applying means, such as piston cylinder means are arranged to apply loads to a load application point of the test sample whereby the load applying means are controlled by error compensated control values. The rated displacement value or the actual displacement value of a first load applying means is supplied as a compensation or correction value to the control circuit means of one or more load applying means through a computer which calculates the correction or compensation value as a function of a curve which represents the displacement of the load application point and which displacement depends on the geometric configuration or structure of the sample to be tested.