Abstract: A moldboard support is pivotally hinged to its carrier and has a medial rearward portion pivotally connected to a lower link, the upper portion of the link having an arcuate ramp with a portion engaging a detent mounted in an upper link that is pivotally connected to the lower link at its lower end portion and to the carrier at its upper end. The support and two links form a toggle in which the pivot pin connecting the two links is normally slightly rearward of a line connecting their upper and lower pivot pins and that permits the support to pivot rearwardly and upwardly when an obstruction is met and to return by gravity when the carrier is raised. The operating angular position of the support may be changed by shifting the pivot pin for the upper link.A tension spring is mounted to exert an initial resetting force on the moldboard support in its upper tripped position to assist in breaking away from impacting materials.

Abstract: A reversible moldboard plow has a plow carrying beam swingably mounted at the rear crossbar of a frame which carries trunnion mounted cylinders connected to the beam for moving the beam, the front of the frame carrying hitch pins for connection to a tractor hitch, the hitch pins being vertically movable in alternate relation in order to tilt the frame and the beam with the moldboards supported thereon. The hitch pins may be moved by independent cylinders and pistons or, alternately, by the movement of a transverse hitch bar on which they are mounted.