Design modification and analysis of an improved treadle thresher

Soe Hlaing

Date

1993

Abstract

An improved treadle thresher with a slip-drive system was developed and evaluated. Some optimum conditions were determined to develop a treadle thresher which is portable, simple, low cost, requires less effort and performs with high efficiency. The slip-drive system in this improved treadle thresher is different from earlier gear driven or chain driven pedal thresher. The slip-drive system not only improves the convenience of the operator but is lower in cost and lighter. This improved treadle thresher offers an attractive alternative in manual mechanical threshing because of its simplicity and light weight. The main modifications are as follows: 1. The slip-drive friction pulley was optimized in diameter and width of the pulley groove to obtain the required drum speed and improve the reliability of the rope. Laboratory tests showed that this modification improves life of the nylon rope from 20 hours to 200 hours. 2. The existing threshing teeth was bent 30˚ forward and twisted 30˚ to expose more surface contact with the paddy bundles. Results of laboratory and field test showed that modified tooth gave the highest threshed grain percentage among 6 different threshing tooth configuration e.g. 94.29% with RC2 rice variety, 24.12% MC (wb) in the field. 3. A pair of modified sand filled flywheels not only reduced the speed fluctuation of the threshing drum but also minimized the operator?s effort. Laboratory test showed that by using these flywheels, if the paddy was loaded at 20-30 sec from the start, the loaded power requirement was practically the same as the no load power requirement. This thresher needs only 40% of average available power and being convenient to work, woman can comfortably operate the thresher. The power required was only 2/3 of the comparable Chinese thresher. 4. A cleaning screen was also added to separate the grain and material-other-than grain. In this research, optimum size of threaded pulley was 30 mm diameter and 30 mm width; optimum stiffness of spring was 36 kg/m for each slip-drive unit, optimum exposure time in test conditions was 6 sec and optimum input pedalling speed was found out to be 75 stroke/min. The weight of machine was only 42 kg, is 28% lighter than the Chinese pedal thresher. It is quite portable. From the field test results, the modified treadle thresher has a throughput of 140 kg/h for RC10 rice variety, 20% MC 9wb) with 2 operators. The estimated raw material and fabrication cost for the modified treadle thresher is around 2000 pesos (US dollars 80).

Document Type

Master Thesis

Degree

Master of Science in in Agricultural Engineering

Language

English

LC Subject

Rice

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 995 1993 A2 S64

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