Abstract
For the purpose to increase and stabilize the draft of the garden tractor, the author tried a simple automatic draft control hitching. Its mechanism is shown in Fig. 1, a tillage implement, for example, a plow is attached to a pivot O of a stay AO fixed to the garden tractor, and a beam fixed to a moldboard is attached to the tractor body through a spring k. Any change of soil resistance changes the amount of deflection of the spring, then the pitch of the plow, so that the depth of it changes, maintaining the draft automatically constant. Theoretically introducing the control differential equation (6), to prevent the hunting the frequency response of this system (Fig. 4) is investigated, and the optimum ranges of the spring constant, the moment of inertia and the natural frequency are determined. With experiments it is found the plow enters the ground faster and deeper than the ordinary mounting method. This system is easily interchangeable to the ordinary or fixed mounting methods.
