Tractive performance of a power tiller in swampy peat soils | |
| Author | Agung Hendriadi |
| Call Number | AIT Diss. no.AE-02-01 |
| Subject(s) | Vehicles Agricultural machinery Tractors--Wheels |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. AE-02-01 |
| Abstract | Ten years ago, Indonesia started to reclaim swampy areas to use for agricultural production especially to support the transmigration program in South Sumatera. Low bearing capacity is a major limitation for the adoption of existing design of power tillers without modifications in these fields. This study was aimed at investigating the suitability of existing design of a power tiller with cage wheel for use in swampy soils, identifying the problems and suggesting the ways to improve the working of the power tiller in these soils. The study was carried out in a swampy area in South Sumatera. The shallow peat lands in swampy areas, generally utilized for paddy farming, were selected for this study. A laboratory soil bin (12 m x15 m x 1 m) was filled with peat soil taken from these lands. Soil morphology was observed directly in the field, while some chemical and physical properties were analyzed in the laboratory. The soil properties at various moisture contents, which affect the machinery performance, were determined. A Special test rig/trolley was developed and used to measure the tractive performance of a single cage wheel of a power tiller in the soil bin. This helped to investigate the traction problems of existing design of cage wheel, study the effects of geometric parameters, viz. lug angles (15, 25, 35 and 45 deg); number of lugs (14, 16 and 18) and dimensions (length x width: 325 mm x 80 mm, 375 mm x 80 nun and 275 mm x 95 mm) on the wheels performance. The test wheel was powered by a gasoline engine of 5.6 kW. Its total weight was set about half the weight of commonly used power tillers (as only one wheel was used for testing) in Indonesia. The test wheel was free to sink. An instrumentation system to measure the tractive performance was developed. After finding the appropriate design parameters OFA cage wheel, a pair of the cage wheel was fabricated and mounted on a power tiller for testing in the field. An L-shaped force transducer was deve10ped to record the horizontal and vertical forces. A real-time data measuring system was developed. From the studies on soil properties, it was observed that the soil profile consisted of, from top to bottom, a peat layer (up to 23 to 45 cm from surface), a transition layer and a mineral layer. Peat material was found to be hemic with average organic matter and fiber content of 50.5 and 43.2% respectively. The ground water existed at the depth of 19 to 36 cm from the soil surface when the land was not flooded. The bulk density of soil was very low with a maximum value of 0.3 g/cc only. The soil was found to become weaker as the soil moisture content increased. In flooded condition, the values of cone penetration resistance over the depths of 20-25 cm was 83 kPa. Soil cohesion, internal friction angle, soil adhesion and soil-metal friction angle were 10.45 kPa, 21.51 deg, 0.84 kPa and 11.60 deg respectively. Cohesive modulus of sinkage, frictional modulus of sinkage and sinkage index found were -34.90, 23.28 and 0.20 respectively. A study on the tractive performance of the existing design of cage wheel revealed that the maximum tractive efficiency in flooded conditions was relatively low (37.6%) compared to when it was used in a normal paddy field (about 50-55%). Deep sinkage (maximum of 28 cm) and high wheel slip (55%) were identified as the major problems which needed to be overcome. The study on the effect of lug angle and number of lugs variations concluded that the best lug angle and number of lugs selected were 35 deg and 14 lugs on a wheel respectively. In order to imprOve the tractive performance, this selected lug angle and number of lugs were adopted for further studies to decide the iii dimensions of the lugs. Though 375 mm x 80 mm lug gave best performance, due to practiced limitations, the best lug size selected was 325 mm x 80 mm. However, it was found that even for the selected size, at maximum tractive efficiency, the depth of sinkage (>20 cm) was still high. Therefore, further modifications were directed to overcome the sinkage problem. The circumferential flat rings (30 mm width) were fabricated and installed on the inner side of the lugs. Two rings were found to be sufficient. The maximum tractive efficiency, wheel slip, drawbar power and sinkage at maximum tractive efficiency of the wheel with two flat rings were 51.1%, 46.7%, 0.25 kW and 16 cm respectively. In order to confirm the results from the soil bin test, cage wheels with one and two flat rings were tested in the field. It was found that the maximum tractive efficiency was 55.6%, which was higher than that obtained in the soil bin when two rings on the wheel were used. While for the cage wheel with one ring, the maximum tractive efficiency was 46.3%, which was lower than that obtained in the soil bin test. Compared with the existing design, using the cage wheel with 2 flat rings, the maximum tractive efficiency could be improved from 37.6 to 55.6%, maximum drawbar power could be increased from 0.22 to 0.60 kW and sinkage could be reduced from 28 to 14 cm. The use of a power tiller with this modified cage wheel design is expected to ease the problems faced during working in the swampy peat soils. |
| Year | 2002 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. AE-02-01 |
| Type | Dissertation |
| 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) | Salikhe, Vilas M.; |
| Examination Committee(s) | Singh, Gajendra;Apisit Eiumnoh; |
| Scholarship Donor(s) | The Government of Indonesia (PAATP) Project); |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2002 |