Computer simulation of ballast management for agricultural tractors P.K. Pranav a, * , K.P. Pandey b a Department of Agricultural Engineering, North Eastern Regional Institute of Science & Technology, Itanagar-791109, India b Department of Agricultural and Food Engineering, Indian Institute of Technology, Kharagpur-721302, India Received 8 November 2005; received in revised form 10 November 2008; accepted 4 December 2008 Available online 29 January 2009 Abstract The ballasting weights on farm tractors are rarely distributed optimally resulting in poor tractive efficiency and soil compaction. The need for a comprehensive and concise method to optimize farm tractor ballasting has initiated the development of user-friendly software that incorporates existing theoretical and empirical models. The Windows based software written in Visual Basic Ó provides a collection of data entry panels associated with tractor, soil, tyres and implement. The software calculates the tractor performance parameters including the optimal ballasting on rear and front axles. Software results estimated ballast requirement within 88–96 percent of field data. Ó 2008 ISTVS. Published by Elsevier Ltd. All rights reserved. 1. Introduction The majority of the tractors manufactured in India and many other developing countries fall in the category of two-wheel drive tractors, and they are in the power class range of 15–75 kW. These tractors are generally equipped with bias-ply tyres for tractive purposes. Research shows that about 20–55 percent of the available tractor energy is wasted at the soil–wheel interface. This energy wears the tyres and compacts the soil to a degree that may cause detrimental crop production [1]. Ability to predict and optimize the performance of tractors during field opera- tions has been of great interest to scientists and engineers. The subject of tractor ballasting has received renewed interest because it is considered one of the important factors affecting tractor performance, particularly on sandy loam soils. Ballasting determines how well a tractor mass is matched to implement load. The addition of ballast to a trac- tor is usually accomplished by adding cast iron weights to drive wheels for developing more tractive effort, and to front wheel for improved stability. Adding too much ballast will result in excessive power loss due to increased rolling resis- tance, but insufficient ballast will cause power loss because of the increased wheel slip. Therefore, ballasting is a compro- mise between rolling resistance and wheel slip. Past studies indicate that the majority of tractors tested are incorrectly ballasted [2]. This is mainly because a considerable amount of time and physical effort are needed in properly ballasting a tractor. Optimized ballast management between the front and the rear wheels can maximize tractive efficiency and min- imize compaction while increasing tractor drive-train life and return on investment. During the last one decade, a large number of computer models and simulation programs have been developed for predicting tractor performance. Such programs have also been used to determine the relative importance of many fac- tors affecting field performance of tractors without conduct- ing expensive as well as time-consuming field tests [3]. However, these programs have not been focused sufficiently on tractor ballast management. The objective of this study was to develop an optimization program for predicting the drawbar performance of rear wheel driven tractors, during field operations by varying the weight distribution on front and rear wheels and validate the results with field data. 2. Review of literature Gee-Clough et al. [4] suggested that there is an optimum dynamic weight on rear axle below or above which tractive 0022-4898/$34.00 Ó 2008 ISTVS. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jterra.2008.12.002 * Corresponding author. Tel.: +91 9436228995; fax: +91 0360 2244307. E-mail address: pkjha78@yahoo.com (P.K. Pranav). www.elsevier.com/locate/jterra Available online at www.sciencedirect.com Journal of Terramechanics 45 (2008) 185–192 Journal of Terramechanics