Dynamics of 3 Points Linkage Hitching (VII)

Vertical Motion of a Controlled Plow

Abstract

Dynamics of a plow which is controlled with a hydraulic device are discussed. Summary of the conclusions are as follows.
1. Stability of the draft control and position control system is kept for hard control spring, high loop gain and small timeconstant of theh ydraulic system.
2. Restoring orientation of 3 points link hitch mechanism is equivalent to the feedback of the powerpiston.
3. From the viewpoint of stability in higher frequency domain or in higher tractor speed, pneumatic control is more adequate than hydraulic control.
4. Vertical spring constant at the hitch point becomes greater when controlled hitching mechanism is employed. And more quick response of the plow and the effective weight transfer are expected.
5. Quick response of the plow is brought by the great loop gain and small time constant of the control system, however, limitation of the performance is existed. For an example of a 35 PS tractor, the limitation of response locates around 0.5sec. of overall time constant.
6. Vertical position variation due to the rear wheel load variation which is resulted from the control action decreases the controlled performance. Soft ground and soft pneumatic tires are unsatisfactory from the standpoint.