Study on parameters affecting vibration in height adjustment of a combine harvester header model

In Thailand, vibration problems often occur with rice combine harvester automatic header height adjusting systems. This study aimed to identify parameters for reducing the vibration and managing response time for harvesting speed configuration. An experimental combine harvester header model was designed to automatically adjust three parameters: total movement time, time ratio, and final phase distance within vertical movement ranges of 200, 250, or 300 mm. These parameters were controlled using a proportional flow control valve and a professional learning community (PLC) control unit. The results showed that increased time ratio, final phase distance, and total movement time significantly reduced average vibration amplitude. Higher time ratios corresponded to lower vibration amplitude during changing stages but higher amplitude during stopping stages. Vibration amplitudes during starting, changing, and stopping stages ranged from 0.622 to 1.373 mm, 0.042 to 1.097 mm, and 0.132 to 0.902 mm, respectively, for 200, 250, and 300 mm vertical movement distances. To reduce vibration in the first and second wave phases, precise control of start and final speeds through time ratio and total movement time was necessary. Minimizing the time ratio and final phase distance effectively reduced vibration amplitude in the third wave phase.