Abstract: The invention concerns a method of testing the hardness of workpieces (22), wherein an impact body (20) is moved onto the workpiece (22) to be tested such that it impinges thereon (along a forward path) and rebounds thereof (along a return path). On both the return and the forward paths, a movement value of the impact body (20) is detected by a contactlessly operating device and a measure of the hardness of the workpiece (22) is obtained from the difference between the forward and return path movement values. The movement value is detected at at least two points on the forward path and at at least two points on the return path. Corresponding to each movement value detection point on the forward path is a point on the return path at a substantially similar distance from the point of impact.

Abstract: An apparatus for testing hardness under load has a measuring sensor in the form of a manual apparatus in which a mobile rod-shaped resonator can be slidingly inserted. The free end of the resonator, situated outside the housing, has a measuring tip. The resonator is held against the housing of the measuring sensor by a spring and is linked to ultrasonic converters connected to an electronic generator and to a receiving circuit which records changes in the duration or frequency of the vibrations of the generator. A basic apparatus comprises a display unit and is connected by a connecting line to the measuring sensor. A memory for storing individual parameters of the rod-shaped resonator and the electronic generator is arranged in the housing of the measuring sensor. The basic apparatus is detachably connected by insertion to the measuring sensor.