Cylinder synchronization for an implement lift system

A lift system includes parallel connected cylinder circuits with cylinders mechanically tied together on a first lift wheel arm. The base end of a third cylinder connected to a second lift wheel arm is connected in parallel with the pair of cylinders. The rod end of the third cylinder is constrained for movement with the rod end of a fourth cylinder also connected to the second wheel arm. The rod end of one of the pair of cylinders is connected in series with the base end of the fourth cylinder to thereby constrain the third and fourth cylinders on the second lift wheel arm to move in unison with the pair of cylinders on the first lift wheel arm. Series cylinder circuits move the wing cylinders in unison with the main frame cylinders to keep the implement level. The hydraulic circuit is also plumbed to retract outer wing wheels during wing fold operations to eliminate outer wing wheel interference.