Evaluation of Reliability of Prototype Tractor – Mounted Cocoyam (Xanthosoma spp.) Harvester

An elevator digger type harvester for cocoyam (Xanthosoma spp.) was designed and fabricated at the Federal University of Technology, Akure using locally available materials. The harvester prototype is tractor – mounted and powered from the tractor Power – take – off shaft (P.T.O).  Field tests were conducted to evaluate the effect of different levels of operational parameters on the reliability of the implement. The operational parameters were forward speed (v), rake angle (α) and web speed (n). The harvester was operated at the forward speeds of 2, 4 and 6 km/h, rake angles of 15˚, 20˚ and 25˚ and web speeds of 540, 1000 rpm. These combinations were tested on a factorial basis employing a split - split plot design with three replications. The indices of reliability of the implement investigated were material failure to machine parts, clogging and machine adjustment. Cocoyam cormels were harvested from 10m long rows of crops on clay loam soil with a spacing of 0.8m x 0.6m according to each treatment. The soil moisture content during field experimentation was 9.46 ± 1.02%, and bulk density was 1.18 ± 0.22 g/cm3.  The field tests revealed that machine performance was limited by delays due to clogging and machine adjustments and a high percentage of tuber damage (55%). The analysis of variance performed on the descriptive statistics for machine performance variables obtained showed that the results are significant for only Machine adjustments at P < 0.01.  Keywords: Reliability, Breakdown, Web, Clogging, Material failure, Failure rate, Mean time before failure, Nigeri