EFFECT OF DIFFERENT TILLAGE DEPTHS ON TRACTOR DYNAMIC WEIGHT AND TORQUE
A field study was conducted to reveal the effect of different tillage depths, hence, different draft forces required by a plow, on the weight transferred from a tractor front axle to rear axle, and on the torque applied to tractor rear wheels. The tillage depths incorporated in the study were 5, 10, 15, 20 and 25 cm, and the tillage operation was performed on a loamy sand soil at a moisture content (MC) of 12.55% using a three bottom moldboard plow integrated on an 89.6 kW (120 hp) tractor at an average ground speed of 4 km/h. In addition to the horizontal draft force, the dynamic weights on tractor front and rear axle were measured for each tillage depth and transferred weight was determined. For each tillage depth, total increase in tractor rear axle weight (transferred weight plus effect of draft force) was calculated. Increase in torque at the tractor rear wheels due to the total increase in rear axle weight was also determined.
Results showed that, when the tillage depth increased from 5 to 25 cm, the average required horizontal draft force increased from 10.55 to 15.45 kN (46.4%), however, front axle dynamic weight decreased, on the average, from 18.20 to 14.50 kN (20.3%). Based on measured values, the total increase in rear axle weight was elevated from 13.95 to 22.23 kN (59.4%) when the tillage depth increased from 5 to 25 cm. At a specific tillage depth included in this study, the total increase in tractor rear axle weight was found to be almost equal to the amount of decrease in front axle weight plus the amount of the required horizontal draft force. Due to increasing weight on tractor rear axle, torque at the rear wheels was found to increase with increasing tillage depth. Increasing the tillage depth from 5 to 25 cm caused the torque to increase from 16.79 to 22.46 kN.m (33.74%).
Keywords: Tractor, weight transfer, dynamic, moldboard plow, draft force, tillage depths, torque.