Computer simulation of three-point linkage parameters for virtual hitch point and optimum depth of operation

A computer program is developed in Visual Basic 6.0 to locate the virtual hitch point of tractor with respect to depth of operation and to optimize the three-point linkage parameters for matching the virtual hitch point with the line of pull. The concept of Cartesian coordinate geometry was used in the program development. The virtual hitch point was calculated by solving the straight line equations of lower and upper link of three-point hitching system at particular depth of operation. For determining the line of pull, draft was calculated from ASAE equation and coordinate of centre of resistance was assumed to the 2/3 of depth of operation in the line of centre of gravity of implement. The optimum depth of operation is the depth for which line of pull passes above and near to VHP which was calculated in the program through the iteration process. The locus of virtual hitch point with respect to depth of operation was observed as parabolic. The distance of virtual hitch point from the rear axle centre increases with increase in depth of operation in all cases. The optimum depth of operation for a test tractor was observed as 269 mm using the developed program. This depth depends substantially on lower link (length and link position) and implements parameters (weight and height of hitch point). Therefore, this program may be very useful in simulating the three-point linkage and implement parameters as per the requirement of depth of operation.