The material to be tested is placed on a level table – known as the anvil – which can usually move up and down to accommodate various sizes of sample. It moves up and down on a column that is rigidly mounted to the body of the hardness tester. The ‘test head,’ which holds the tungsten carbide ball, then descends onto the material to make the indentation.

Because of the force needed to make an indentation in steel, a Brinell hardness tester is a robustly constructed machine. In addition to the robust construction, testers usually have electronic circuitry and a computer to run the indentation process. There are exceptions to this: the smallest testers are hydraulic and hand operated and even some medium-sized machines are lever operated, with the operator using a stopwatch in place of software-driven electronic timing.

Most small and medium hardness testers have a characteristic shape somewhat like a square-ish ‘C’. The test sample is placed on an anvil that is fastened to the ‘bottom’ of the C and the indenting components descend from the ‘top’ of the C.  An example is shown in this picture.   The ‘open front’ of the ‘C’ allows long and unwieldy components like beams to be tested.  Where testing of very large samples / components is required, the test head sits within a carriage that is mounted on a rail between two posts.  An example can be seen here.