One important problem in Romania is how to optimize the valorization the nuts, in conditions of large number of small orchards (less than 3 ha), scattered, difficult to find a uniform system of collection. A solution could be a small breaking and peeling machine, cheap and reliable. The paper, a consequence of requesting some owners of walnut orchards, presents the results of experiments with a new active organ (cracking rollers with a synchronous edge), focused on nuts' shear and breakage. It studied the influences of the variety of walnuts (with different sizes of fruits derived from the same variety), on the breaking and peeling process. The experimental research tested 5 Romanian varieties, using 30 different walnuts variety, in the same temperature and humidity conditions. Each nut's dimensions were measured on three rectangular axis and statistical parameter were determined (average, geometric mean, Standard Deviation etc.). After breaking process, the number of broken parts was accounted and statistical analyzed using Microsoft Excel 2016. It was considered that relation between the number of nut pieces after breaking process and initial dimensions' average (arithmetic, geometric and square), could qualify the process. The values of arithmetic (A), geometric (GA), and square (SQA) average of nuts dimensions are very closely (e.g. for one variety, A=30.68 and SQA=30.64). One conclusion was that larger walnuts are easier to break, and the number of pieces in which they break, are lower compared to smaller walnuts. The results will be integrated into a larger study completed with influences of conditions temperature, humidity, as well as walnut variety.