Optimal three-point hitch design to maximize lifting performance

The three-point hitch mounted on tractors was introduced by Ferguson in 1935 and has been modified from the first patent with the introduction of different controls. In recent years, the geometry has not been significantly modified due to the standards that define the application limits. These standards define the geometric constraints of the system as a function of the tractor power and wheelbase. The constraints have been fixed to standardize the connection with implements and limit their movements. The degrees of freedom could be used to optimize the three-point hitch as a function of the design specifications, and in particular to optimize the maximum lifting capacity. Analysis of OECD-Approved reports, confirmed by the authors' experience, shows a high number of three-point hitches with a maximum lifting capacity that is not optimized. The goal of the present work is to provide a design tool to optimize the three-point hitch by maximizing the lifting capacity and satisfying the constraints fixed by the standards. The methodology proposed uses a constrained optimization technique and was validated on an existing three-point hitch. The optimized three-point hitch permits a maximum lifting force about 25% greater than the existing value. The lift arm length, the lower link length, and their pivot point positions are the variables with greatest influence on the objective function. The constraint of a minimum angle of 10° between the mast and the vertical axis is the most limiting constraint on the objective function.