RESEARCHES ON THE MATHEMATICAL MODELING OF THE KINEMATICS OF THREE-POINT HITCH COUPLERS USED AT AGRICULTURAL TRACTORS

摘要

The paper presents an analytical method applied to elaborate and analyze the kinematics of the three-point hitch couplers used at agricultural tractors. The analysis is grounded on the following basic data: kinematic diagram of the three-point hitch couplers, geometrical dimensions of the elements of the three-point hitch couplers, piston relative speed in the lift cylinder. The analysis is carried out with the aim of determining the speeds of all hitch points as well as the transmission ratio of the three-point hitch couplers. The mechanism is divided in three kinematic groups. The study and the mathematical modeling of the kinematics is carried out for each distinct group taking into account the piston speed and position in the lift cylinder. The speed of each hitch point and the transmission ratio of the three point hitch couplers related to the speed of a point positioned on the drawbar or to the speed of the agricultural tractor's center of gravity are further determined. The paper shows the results of the researches conducted on wheeled tractors U 650 and U 650 DT.