DEVELOPING A SMALL COMMERCIAL VIBRATING POTATO DIGGER II. EFFECTS OF DESIGN PARAMETERS ON DRAFT, TORQUE, AND POWER

A single–row commercial potato digger was tested by replacing the fixed blade with a vibrating blade. Four design parameters were generated from amplitude, frequency, and forward velocity data: , the ratio of vibration speed to forward velocity; , the ratio of vibration acceleration to forward velocity; K, the ratio of vibration acceleration to gravitational acceleration; and T, the product of and K. Regression was used for the analysis of draft, torque, and power as functions of the four parameters. Draft correlated best to the parameter T, that is, draft was dependent on all three variables: amplitude, frequency, and forward velocity. Maximum total draft measurements yielded a range of specific drafts from 5.9 N/cm 2 to 10.0 N/cm 2 . A minimum total draft of 8272 N (7.3 N/cm 2 ) was expected when T = 2. Torque and total power correlated best with the parameter K. Regression models for torque and power were all highly significant with K as the independent variable. Total power, defined as the sum of the powers to pull and to vibrate the digger based on the maximum draft and maximum torque, was dependent on the parameter K. This implied that frequency and amplitude of vibration, in order, had major impacts on the total power rather than the forward velocity of the digger. Maximum total power was 13.30 kW (17.78 hp). An expected minimum power requirement for K = 2, recommended as a good design parameter value for a vibrating digger blade design, was 6.84 kW (9.17 hp). Torque and total power are mostly affected by vibrating frequency and secondly by amplitude.