Development of a seat suspension system for a small four wheel tractor | |
| Author | Kiattisak Sangpradit |
| Call Number | AIT Thesis no.AE-04-06 |
| Subject(s) | Tractors--Vibration Chairs |
| Note | A thesis submitted in pa1tial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. AE-04-06 |
| Abstract | To obtain safety and comfort conditions for the tractor operators, the suspension system of a tractor seat was analyzed and modified to minimize the vibration. Experiments were conducted to investigate the effect of seat vibration in a small 4-wheel tractor on its operator and to develop a suitable seat suspension system following ISO guideline, and ergonomic considerations. The general seat vibration characteristics of a small four-wheel tractor were assessed on standard test track (ISO 5008) and an appropriate seat suspension system was designed. Mechanical and ergonomic effects of vibration on operator using conventional seat and the new design were compared following standard test procedures prescribed in the standard test code ISO 5008. The supportive observations on ergonomic aspects were also made viz. the operator heart rate, postural comfort survey, and Cornell ergonomic seating evaluation. The measurements of vibration level were conducted using the standard rough test track built as per the standard ISO 5008 with two operators. The measured vibrations of the existing and newly designed seat were then compared with the IS02631 standard to find the fatigue-decreased proficiency limit. The vibration of existing seat in vertical direction had highest amplitude followed by the vibration in lateral and longitudinal directions sequentially. The critical frequency at 3-4 Hz gave maximum amplitude of around 0.9 m/s2 . The new design, as compared to the existing seat, could significantly reduce the vertical vibration. The newly designed seat efficiently worked within the excess vibration frequency between 2 to 8 Hz with variable damping constants 1,177.7, 716.5, 695.5, 334.7 and 69.4 Ns/m, and spring constant 14,343 Nim. The new seat facilitated the operator to be able to work as long as 8-hour of fatiguedecreased proficiency limit, while that of the existing seat was found even below 4-hour proficiency limit. The developed seat found to be effectively attenuating the hazardous level of bouncing component of the vibration, while the mechanism did not support to attenuate the vibration modes of pitching and rolling. The heart rate of operators were not different on the smooth surface in the three conditions tested. However, the heart rate increased significantly on the standard rough test track. The new seat offered comfort mostly on the operators' abdomen, shoulder, hip, low back and upper back. At the mid-back, new seat reduced the comfort probably due to the armrest hit at the waist in rolling mode that could transfer pain to the mid-back. The Cornell ergonomic seating evaluation concluded that the newly designed seat was more comfortable than the existing seat. |
| Year | 2004 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. AE-04-06 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Food Engineering (AE) |
| Chairperson(s) | Jayasuriya, H.P. W.; |
| Examination Committee(s) | Salokhe, V. M.;Bohez, Erik L. J.; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2004 |