Thesis (M.Eng.) - Asian Institute of Technology, 1993

A thesis submitted in partial fulfilment of the requirements for the degree of Master of Engineering.

The performance of a power tiller manufactured and commonly used by the farmers in Indonesia was evaluated. The evaluation dealt with the field survey, measurements of axle performance, steering clutch performance, drawbar performance, and estimation of the operational cost. The results of interview with the farmers revealed that power tillers without a PTO shaft are commonly used in Indonesia. It is a single forward speed power tiller. A power tiller without a PTO shaft 6.46 kW Kubota G-9008 was selected for conducting the experiments. Maximum axle power and maximum drawbar power of this power tiller were found to be 3.1 kW and 1.6 kW, 5.1 kW and 2.6 kW, 5.5 kW and 3.0 kW for no-load engine speeds of 1650, 2200 and 2350 rpm, respectively. The internal power transmission efficiency at maximum power output was found to be 83 .3 % , while maximum tractive efficiency on dry-land using cage wheel were found to be 56.0%, 59.1%and60.3% for no-load engine speeds of 1650, 2200 and 2350 rpm, respectively. The optimum field operational parameters were found to be 2.27 kN of drawbar pull at 1.2 mis forward speed and 26.1 % wheel slip. The available drawbar power at maximum tractive efficiency was found to be 2.6 kW. While in measuring of the steering clutch performance it was found that the force required to operate the hand steering clutch lever was higher than the capability of hand grip of the operator to operate the hand lever. Therefore, modification of the steering clutch has been proposed to reduce the force required to operate the hand steering clutch lever. Based on results of the field survey, the experimental results, and some standard assumptions, the estimation operational cost of this power tiller for land preparation at BEP = 17 ha/year was found to be Rp.66475/ha (US$ 33.2).