Development of Computer Software for Design of 16+4 Speed Gearbox for Tractor and Practical Validation

Indian tractor industry is now the largest in the world in number of unit production with an average of more than 2 lakhs unit production per year. Export market of tractor is also increasing on an average 30-40% rate. At present most of the tractor models produced in India has (6+2) or (8+2) speed gear box. But it is already proven that more number of speed options can reduce fuel consumption and can increase possibility of power-load matching. To meet the requirement of market demand and better performance, a new “16 forward + 4 reverse” speed gearbox, is required to be designed and developed. To automate the highly technical and time consuming design procedure, a software has been developed by using Visual Basic 6.0 language. Up-shift analysis is very important for efficient gearbox design. During design up-shift spectrum has been kept as even as possible. Slip torque and duty cycle concepts has been introduced for engineering optimization of the gearbox parameters. Introduction of slip torque and duty cycle concept reduced face width of different gears from 9 to 34 %. Stress analysis shows that in all the cases design bending and contact stress are within 10% than the corresponding induced stress values. With the result of the developed software, a prototype of new gearbox has been developed. Haulage testing was carried out with the new prototype. The new prototype resulted in 8.6 % reduction in total fuel consumption for 10 km run on level road as with the new prototype better matching of load vs. pull was possible.