The big square baler is an operating machine that performs the harvesting of hay and crop residues (straw) and the wrapping and baling process of big prismatic bales. The main operating organs of the machine are: i) the harvesting head; ii) the feeder; iii) the compression chamber and iv) the binding apparatus. The required power by the HD1270 big square baler, manufactured by Cicoria in Palazzo San Gervasio (near Potenza, Italy) has been studied. This big baler HD1270 is equipped with specially designed and manufactured devices aimed at reducing the costs of wrapping and baling. Practically these devices are the "Leverage Piston System", the "Top Feeding System" and the "Controlled Binding System", which manage, respectively, the motion of the piston, the feeding of the product and the binding operations. According to the manufacturer's technical specifications, these devices allow minimum required power from the tractor down to only 60 kW. Using an ad hoc high precision torque meter and tachometer, mounted between the tractor power take-off (PTO) and the cardan shaft connecting the HD 1270 big baler, the required torque values and power during the straw wrapping and baling process were measured and recorded. The tests were repeated considering different operating conditions. The obtained results were statistically evaluated in the time domain and clearly showed that the effective required power complies with technical specifications. The variability in stress could induce fatigue phenomena in the components that make up the piston motion transmission chain, with a reduction in their useful life.
IntroductionThe Mediterranean basin is home to centuries-old large olive trees; high-vigor cultivars are widespread, with training forms poorly adapted to mechanical harvesting by trunk/branch shakers. The significant quantity of leaves, the considerable tree height, and the presence of multiple dichotomous hanging branches reduce the transmission of vibrations applied by the branch-shaker machines. Thus, re-shaping pruning may improve the performance of this modern mechanical harvesting method by focusing on removing both the hanging branches and those forming dichotomies. The goal of this study was to evaluate the dynamic responses of large-sized olive trees to pruning (or not) through various field tests under different excitation forces. We hypothesized that more rational pruning could significantly increase vibration transmissions.MethodsTo assess the transmission of vibrations, tests were conducted before and after the pruning on representative trees. Tri-axial accelerometers packed in a small titanium housing were used. Trees were assessed before and after the re-shaping pruning. This study reports the first data about the dynamic behavior of centuries-old tree skeletons, in the context of very large-sized olive trees, while taking into account the effects of two different vibrations application modes: a realistic one represented by the system vibration head-tree, originated when the gripper of a shaking machine wrapped and fastened the main branch of the olive trees, and a more speculative one, represented by a single impulse of a short-duration force originated by a hammer.ResultsAfter pruning, spectral density increased 10 fold in the tertiary branches of pruned trees (ranging 1.0–10 m s−2) compared to that of not-pruned ones (ranging 0.1–1.0 m s−2) at frequency >50 Hz under vibration excitation. Moreover, vibrational decay times (120–150 ms) and amplitude (>10−1 m s−2) were higher under single-impulse excitation.DiscussionA more rational pruning applied to ancient large-sized olive trees significantly increased the vibration transmission under both impulse and vibratory excitation forces, without affected their typical “look”. Moreover, these insights are helpful in turn in achieving maximum fruit-removal efficiency. These insights could be applied to various horticultural conditions which would improve the economic sustainability of monumental olive trees, a key portion of the Mediterranean landscape and cultural heritage.
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