The device has a machine frame (2) attached to a tractor (4) by a three-point linkage, and a soil engaging tool unit (5) suspended on the frame. A trailer roller (7) is connected with the frame, and a working depth adjusting device (18) adjusts working depth of the tool unit. The adjusting device has a trailer-height adjustment unit for height adjustment of the roller relative to the frame. The adjustment unit has a pressure fluid actuator, which acts on a trailing arm (10) of the adjustment unit, and a control device to continuously control the actuator to adjust the depth.
