Abstract: A hydraulic valve device for controlling a double action, piston-type servomotor adaptable for steering a self-propelled agricultural vehicle and including a pair of identical interconnected valve groups, with each group connected to an opposite side of the servomotor and further connected to a source of pressurized fluid and an exhaust outlet, whereby selective actuation of the hydraulic device creates a pressure difference in a servomotor forcing the piston to move in a predetermined direction.

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.

Abstract: An agricultural machine of the type employing an automatic steering system is provided with separate switching devices for switching the steering system on and off. The mechanism for switching the system off is carried by the steering column of the machine and includes elements for monitoring the speed of manual rotation of the steering wheel to switch the automatic steering system off when the driver of the machine turns the steering wheel more rapidly than a predetermined speed of rotation. The mechanism for turning the automatic steering system on includes a pedal-operated switch which is covered by a displaceable housing, so that the automatic steering system can be turned on only by conscious effort of the driver. The on and off switching signals provided by these two mechanisms are coupled to an electronic switch forming a portion of the automatic steering system, and the switch-off signal normally predominates so that the preferred state of the system is its off condition.