@article { author = {Zamani Dehyaghoubi, M. A. and Jafari Naeimi, K. and Shamsi, M. and Maghsoudi, H.}, title = {Development and Evaluation of an Onion Harvester Machine with Excrescence Axes}, journal = {Journal of Agricultural Machinery}, volume = {8}, number = {2}, pages = {249-262}, year = {2018}, publisher = {Ferdowsi University of Mashhad}, issn = {2228-6829}, eissn = {2423-3943}, doi = {10.22067/jam.v8i2.62726}, abstract = {Introduction It is common to use rod weeders for onion harvesting according to their prevention of root blocking in front of the machine and separation of onion bulbs from soil by shaking. Chesson et al., (1977), used a rod weeder for manufacturing an onion harvester. This machine had a rectangular rotor axis with 25mm×25mm cross section. The rotor power was provided by a hydro-motor. An investigation into onion losses during the harvesting operation showed that the majority of crop damages have been occurred due to the collision of rods with onion bulbs. Therefore, the objective of this study is to design and evaluate an onion harvester based on rod weeders with the capability of crop harvesting with minimum damage. Materials and Methods The main components of the examined onion harvester are chassis, furrower, and power transmission system and excrescence axes. Rectangular 100mm×100mm and 40mm×80mm profiles with 4mm profile thickness are used to fabricate the chassis. The furrowers were installed on each side of the chassis as the first parts of the harvester that comes into contact with the soil. Power transmission system provided rotation of two axes from both sides of the machine due to the lack of space for working of two chains on the one side. Therefore, a gearbox having one input shaft and two output shafts was selected for the machine. The gearbox output shafts turn the rotors with a reduction ratio of 1 to 3.5. The rotary motion of the excrescence axes cuts and moves the soil located under the onions bulbs upward and finally the onion bulbs are placed on the soil surface. Therefore, excrescence axes can be considered as the main part of the onion harvester. The excrescence shape of the axes were created by star wheels. Star wheels had a hole with a square section in center (30mm×30mm), for installing them on their shaft. Choosing this kind of the connection, dose not let star wheels to move freely. Also to limit the lateral movement of the star wheels on axis, metallic spacers were used between the adjacent pairs of them. To evaluate the machine performance three variable factors were defined: working depth (20 and 26 cm), forward speed (3, 4.5 and 6 km h-1) and rotational speed of the excrescence axes (150, 220 and 290 rpm). The conducted experiments were analyzed in a complete randomized design with three replications. Results and Discussion The analysis of variance showed that the working depth and forward velocity of axis had significant effect (in 5% level) on the success rate of onion harvester. Also the interaction between depth and forward velocity and the interaction between rotational speed of axes and forward speed were significant. The interaction between depth and rotational speed of axes and the interaction between depth, rotational speed of axes and forward speed were not significant. Evaluation of the interaction between depth and forward velocity showed that the most success rate of onion harvesting was in 20 cm depth and forward velocity equal to 3 and 4.5 km h-1. The least success was gained in 26 cm depth with 4.5 and 6 km h-1 forward speed. Evaluation of the interaction between rotational speed of axes and forward speed showed that the most success in the onion harvesting was occurred with a machine having 3 km h-1 forward velocity and 150 rpm rotational speed and also 4.5 km h-1 forward velocity and 220 rpm rotational speed. Conclusion The success rate of the onion harvesting decreased by increasing the working depth of the machine and axes distance to the onion bulbs. Also with excessive forward velocity the success rate of onion harvesting decreased because of difficulties in controlling the tractor guidance in straight line. The best performance of this onion harvesting machine was in 20 cm depth, 4.5 km h-1 forward velocity and 220 rpm axes rotational speed. Adjusting the machine working parameters according to these values, the ratio of the linear speed of the star wheel tips to the forward velocity of the machine (kinematic index) was equal to 0.82.}, keywords = {Forward velocity,Kinematic indices,Rotational speed,Working depth}, title_fa = {ساخت و ارزیابی دستگاه برداشت پیاز با محورهای زائده‌دار}, abstract_fa = {یکی از پرهزینه‌ترین و مشکل‌ترین مراحل تولید پیاز، برداشت محصول است. در این تحقیق ساخت و ارزیابی یک دستگاه جدید برای برداشت پیاز ارائه شده است. در روش جدید برداشت، حرکت انتقالی و دورانی محورهای زائده‌دار دستگاه باعث بریده شدن، گسیختگی و به‌هم خوردن لایه خاک زیر غده‌ها می‌گردد. با توجه به جهت چرخش محورها، این گسیختگی موجب حرکت رو به بالای خاک، جدا شدن خاک از غده‌ها و روی سطح قرار گرفتن محصول می‌شود. دستگاه ساخته شده دارای طول cm 126، عرض cm 156/5 و ارتفاع cm 98 می‌باشد و 112 کیلوگرم وزن دارد. ظرفیت مزرعه ای این دستگاه برابر 0/6 هکتار در ساعت است. به منظور ارزیابی دستگاه از نظر تأثیر سرعت دورانی محورها، سرعت پیشروی و عمق کار بر کارکرد دستگاه از آزمایش فاکتوریل سه فاکتوره در قالب طرح کاملاً تصادفی و سه تکرار استفاده شد. کارکرد دستگاه با اندازه‌گیری درصد موفقیت در برداشت شدن غده‌ها به صورت سالم ارزیابی گردید. آزمایش‌های انجام شده نشان‌دهنده معنی‌دار شدن تأثیر عوامل سرعت پیشروی و عمق ‌کار بر موفقیت در برداشت محصول بود. این در حالی است که تأثیر سرعت دورانی محورها، اثر متقابل عمق کار و سرعت دورانی محورها و اثر متقابل سه‌گانه معنی‌دار گزارش نشد. همچنین، درصد موفقیت در برداشت به اثر متقابل سرعت دورانی محورها و سرعت پیشروی و اثر متقابل سرعت پیشروی و عمق کار وابسته بود. نتایج نشان داد که بهترین کارکرد دستگاه در عمق کار 20 سانتی‌متر، سرعت پیشروی 5/4 کیلومتر در ساعت و سرعت دورانی محورها برابر 220 دور بر دقیقه حاصل شد.}, keywords_fa = {سرعت پیشروی,سرعت دورانی,شاخص سینماتیکی,عمق کار,محورهای زائده‌دار}, url = {https://jame.um.ac.ir/article_32905.html}, eprint = {https://jame.um.ac.ir/article_32905_13954ddb3aac84ecc6a6a451896a4710.pdf} }