PURPOSE: To enable the cultivator to be automatically lifted from the ground lightly with a small operating force by a method wherein rotating wheels of a travelling vehicle coupled with the cultivator at its rear part are repeatedly engaged with and disengaged from a running transmission case.

CONSTITUTION: When a tilt lever 17 is tilted backwards by a predetermined stroke, a rotary cam body 20 is rotated by a predetermined angle. During this rotation, the cam body 20 rides over a cam projection provided on a cam follower 21, so that the follwer 21 is pushed in the direction X, that is, in the direction of axis of rotation. The pushing operation of the cam follower 21 separates and disengages a movable body 16a and a fixed body 16b of a clutch device 16 from each other, and when the cam body 20 rides over the cam projection, the device 16 is disengaged by the reverse action. Accordingly, by stopping the running temporarily so that the whole system is rockally swayed forward by its inertia with the contact points between the wheels and the ground serving as a fulcrum, the cultivator can be automatically lifted from the ground with the small operating force.