A seeding machine comprises a main frame segment and two wing frame segments. The wing frame segments are provided with a rear rank of planting units that are mounted to the wing frame segments by pivot arms that extend downwardly and rearwardly from the wing frame segments. The pivot arms are pivotally mounted to the wing frame segments by a rock shaft having an actuator bell crank. The bell crank is coupled to a linear actuator for rotating the rock shaft relative to the wing frame segments. The pivot arms have a working position, wherein the planting units are in contact with the ground, an intermediate holding position, wherein the planting units are raised out of the ground, and a transport position, wherein the planting units have been pivoted on their noses into their substantially vertical transport position. To maintain the rear rank of planting units in the intermediate holding position, a U-shaped stop is placed over the linear actuator so that the linear actuator cannot retract.