DESIGN MODIFICATION AND PERFORMANCE EVALUATION OF THE DE-STEMMER UNIT OF CASSAVA HARVESTER

Abstract

An existing cassava de-stemmer unit was modified and evaluated for performance. It is a front mounted implement. It consisted of a circular saw blade, rotation direction conversion unit (bevel gear), chain and sprocket, spikes, spur gear and an electric motor (5.22 kW) to operate the saw blade and a main frame in which all other components are attached. The cutting of the cassava stems is achieved by placing the de-stemmer attached to the front of the tractor at the base of the cassava stem to do the cutting. The machine was tested on a cassava farm plot. Modifications were made with the belt and pulleys replaced with chain and sprockets, the spikes of the row packer were replaced and also inclined at an angle of 30° and the speed of the gasoline engine was reduced. The performance of de-stemmer unit was tested with 3 levels of cutter teeth, 3 tractor approach speeds and 3 cutting shaft speeds arranged in a randomized complete block design (RCBD) of a 3×3×3 factorial experiment with three replicates in each treatment. Comparison between treatment means were done by least significant difference (LSD) at the P˂0.05. The chain and sprockets help to prevent slipping during operation caused by belt and pulley, adjustment in spikes allows the packing of the cassava stems to be done neatly without damaging it and the reduction in speed of the gasoline engine makes the chain and sprockets to work at a required speed. Test results indicated that the highest cutting quality was achieved when 90 teeth circular saw was used, when operated at a speed of 1036.36 rpm and with a tractor approach speed of 2.5 km/h. With this, the minimum average cutting capacity was found to be 5,034 stakes/h (40,272 stakes/day of 8 h) with cutting efficiency of 90%, which can help in covering more than 3.2 ha/day. The stems were undamaged when operated at these conditions and showed satisfactory cutting efficiency. The research thus established the influence of cutting speed, cutter teeth and forward speed on the performance of cassava de-stemmer for efficient production of cassava on large and small scales.