the wheels 14 being lowered to raise the working tools above the road surface see the solid showing of fig6 when the implement is brought onto a field to be worked the wheels are lifted to the desired height to permit tool operation hydraulic fluid is supplied to cylinder 40 and actuator 44 moves generally outward rollers 50 51 move outward along tracks 55 and 56 and link 36 acts against pin 47 to rotate hinge member 23 and wing 12 closkwise about pin 25 to about the position showing in phantom in fig6 when the weight of the wing moves past vertical the force exerted on actuator 44 changes from one of compression to one of tension at this point link 36 laterally engages stop means 35 so that the link acts as a lever of the second class and further actuator motion allows the wing to complete its inversion see fig3 until it lies as an extension of body 11 actuator operation is continued until the link 36 moves at least slightly away from stop means 35 to allow some movement between the wing and the body whereby to accommodate changes in terrain when the field work is completed motor 40 is hydraulically energized to draw actuator 44 generally inward link 36 drawn into engagement with.