Purpose: This study was conducted to understand the work performance of crank-type rotavators and compare them with those of rotary-type rotavators in Korean farmland conditions. Methods: Tillage operations were carried out using both rotavators with the same nominal rotavating width and rated power. During the operations, PTO speed and torque, actual work speed, and rotavating width and depth were measured. To evaluate work performance, pulverizing ratio, inversion ratio, and specific volumetric tilled soil were calculated and compared for each rotavator. Results: It is found that the crank-type rotavator has better specific volumetric tilled soil performance and deep tillage, while the pulverizing ratio is worse. Conclusions: Crank-type and rotary type rotavator have diffenent properties each other in several work performances. It's important, therefore, to choose a suitable type of rotavator that satisfy the farmer's requirements in accordance with the condition of field and the purpose of tillage operation.
Six models of operator seat supplied to local tractor manufacturers were tested in the laboratory in accordance with ISO 5007 and 78/764/EEC. No models out of the six met the allowable damping and transmissibility performance criteria of both ISO 5007 and 78/764/EEC. From the ISO criterion standpoint, one model failed in damping performance and 4 models in isolation performance. From the 78/764/EEC criterion standpoint, 4 models failed in damping performance and 4 models in isolation performance. However none of them failed in all of the criteria, either. Each model met the one acceptance criterion but failed in another. This indicated that operator seat must be improved to meet the current ISO 5007 or 78/764/EEC and the exposure limit value that will be enforced in EU tractor market from 2014 by EU Directive 2002/44 EC.
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