An agricultural implement, having a tool bar that is pivoted forwardly to initiate the conversion of the implement from a working position toward a transport position, including left and right wing members extending in opposing directions to respective distal ends, is provided with a lift assist mechanism to support the distal ends of the wing members as the tool bar is pivoted forwardly to an intermediate transport position. The lift assist mechanism includes a frame pivotally mounted to each respective wing member, a lift assist wheel providing ground-engaging support for the wing member, and a lift assist actuator that controls the pivoted movement of the lift assist mechanism to maintain the lift assist wheel in supporting contact with the ground until the tool bar has been rotated approximately 60 degrees from the lowered working position toward the raised intermediate transport position. A cable extends from the lift assist mechanism to a toll bar lock apparatus to release the tool bar lock only when the lift assist mechanism has been positioned for proper support of the wing member during the pivotal movement of the tool bar from the intermediate position rearwardly into the working position. A hydraulic circuit controls the operation of the lift assist actuators and the tool bar actuators to effect a coordinated action between them so as to maintain proper support for the wing member during the pivotal movement of the tool bar.