In this research, first, a moldboard plow was attached to the tractor and the coordinates of the path of lower and upper hitch points were measured in the movement range of the lift arms. Then, with the aim of investigating the effect of the geometric parameters of 3-point hitch system on its performance, SolidWorks software was used to simulate the motion of the 3-point hitch system. By using the measured data, path of the hitch points was plotted and geometric performance parameters were calculated.
The workshop results showed that when the upper link was attached to the lower pivot point, the vertical convergence distance was less than the ASAE standard value. Therefore, when using tillage implements, it is better that the upper link to be attached to 2rd or 3rd pivot point, and if the lower pivot point is used, the stability of the tractor may be disturbed. The simulation results showed that by increasing the distance of the connection point of the lift rod to the lower link, the mechanical advantage increased to 3.18, but the movement range of the arms decreased by 95.28 mm. Also, by reducing the length of the lift rod, the mechanical advantage increased to 3.16, while the movement range of the arms decreased by 487.11 mm.
By reducing the distance of the connection point of the lift rod to the lower link, as well as increasing the length of the lift rod at heights lower than the ASAE standard for lower links, the position of the virtual hitch point was moved to the rear of the rear wheels of the tractor. This may affect the stability of the tractor, especially on hills.