Abstract: A self-propelled harvesting machine of the type having an automatic steering system is provided with a pair of feelers extending toward one another from the facing surfaces of a pair of plant row dividers located at the forward end of the machine. Each feeler is mounted for motion within the casing of one of the dividers in cooperation with a magnetic transducer located within that casing, and extends from the interior of the casing through an elongated slot in the side wall of the casing. The external portion of each feeler extends in a rearward direction relative to the side wall of the casing and has a comparatively shallow convex arcuate configuration terminating at a free end of the feeler which is located to the rear of the rearward end of the slot.