The axial testing equipment consists of a set of elements that are used to apply tensile-compression loads on the specimens, with the aim of studying the behaviour and resistance of the material. Independently from the force application method. These kinds of machine are designed to drive the piston at a controlled speed. They have to be able to vary the load application speed and to accurately measure the forces and strain in the specimen.
In the case of servohydraulic machines, an hydraulic pump supplies high pressure oil to the machine. This oil is stored in an accumulator, reaching the hydraulic piston (actuator) through the servohydraulic valve. The actuator is joined to one side of the specimen, the other side is joined with another clamp to a headstock. The free headstock allows the adjustment of the geometry before the specimen assembly and it stays fixed during the test. So, the actuator is the only part that moves in the system.