ENHANCEMENT OF STABILITY OF CURVILINEAR MOTION OF THE COMBINED MACHINE AND TRACTOR UNIT ON THE BASIS OF THE INTEGRATED GENERAL PURPOSE ROW CROP WHEEL TRACTOR
At the present time in the world's practice there is an expansion of highly-efficient integrated general purpose row crop four-wheeled tractors that are capable to fulfill operations being in part of wide-cut combined machine and tractor units (MTU) with front and rear mounted machines. However, these units are characterized by low stability of motion, so one of the priorities is an enhancement of stability of the combined MTU motion, including curvilinear type. The authors conducted experimental studies of the combined mounted unit during its motion on the headland in a number of ways: (i) front steer wheels; (ii) front and rear steer wheels with synchronous change in the steering angle of the wheels in all directions above the frame of the tractor; (iii) combined steering motion with synchronous change in the steering angle of the wheels in one direction above the frame of the tractor at the beginning of the turn and the front steer wheels in the area of steady steering motion. It was revealed that the implementation of the combined steering motion contributes to even load distribution on the tractor axles, reduction of their vertical acceleration by 31-65% and acceleration of the translational motion of the MTU by 38-63% in comparison with traditional methods of steering motion. The results of measurements of x -axis of abscissa and y -axis of ordinate of the circular non-loop steering corresponding to the trajectory outlined by the kinematic center during different types of steering motion showed that the combined type is optimal for maintaining the stability of curvilinear motion. The combined type provided a reduction in the transverse and longitudinal displacement of the combined MTU by 0.7-1.7 m and by 2.20-2.46 m, respectively, in comparison with the first studied type of steering motion, and by 0.27-0.53 m and 0.6-0.9 m, respectively, in comparison with the second studied type of steering motion. Consequently, the headland surface area decreased by 28% and 10%, respectively.