Tensile testing machine

A tensile testing machine comprising:

• a frame provided with a first fastening element at a first end of a test specimen whose elongation is to be measured along a tensile axis;
• and
• tensile means adapted to exert a traction along the tensile axis and provided with a second fastening element, forming an axial bar, at a second end of the specimen, coaxially to the tensile axis,
• wherein the tensile testing machine further comprises:
• a first sliding plate slidably mounted along the second fastening element and on which a first part of elongation measuring means for measurements of said elongation parallel to the tensile axis is mounted,
• a second intermediate plate, which is fixed to the second fastening element and to which a first guide rod is fixed, the first guide rod extending parallel to the tensile axis and passing freely through the first sliding plate,
• a third sliding plate, which is slidably mounted along the second fastening element and to which a second part of the elongation measuring means is attached,
• an elastic return means returning the first and third sliding plates towards each other axially,
• a second guide rod parallel to the first guide rod, which freely guides the first and third sliding plates axially, by being disposed at their level, and
• first and second deflection rods, sensing the first and second fastening elements, respectively, the first deflection rod being fixed with the first sliding plate through which the second deflection rod passes, the second deflection rod further coming to bear against the third sliding plate, to act on the third sliding plate parallel to the tensile axis, so that the elongation measuring means detect, parallel to said tensile axis, a displacement between the first and third sliding plates.