Determination of Engineering Properties of Coleus Pertinent to the Design of a Digging-cum-Windrowing Unit

Coleus (Solenostemon rotundifolius) is an important minor tuber crop grown in the homesteads of Kerala and Tamil Nadu. There was a demand for mechanisation for harvesting the tuber because the conventional method of harvesting followed was tedious and time-consuming. For the design and development of a coleus harvester with reduced drudgery, the design parameters were selected with respect to the tuber properties. Random sampling was carried out for determining the physical and frictional properties of coleus. The average values of physical properties such as length, width, thickness, geometric mean diameter, sphericity, surface area, volume and bulk density were found out as 44.56 mm, 27.36 mm, 24.50 mm, 30.99 mm, 0.70, 3029.69 mm2, 15786.50 mm3 and 718.21 kg m-3 respectively. The angle of repose was determined as 30.83° and the coefficient of static friction was found out as 0.73, 0.69 and 0.81 on galvanised iron, stainless steel and plywood surfaces respectively. These data were used for the design of various components of the harvester.