Cylinder synchronization for an implement lift system

A hydraulic lift system for a multi-sectioned agricultural implement having a main frame and outer wing frames movably connected to the main frame, the lift system comprising:

• first and second lift wheel arms connected to the main frame;
• first and second lift cylinders having rod and base ends, the rod ends of the first and second lift cylinders connected to the first lift wheel arm and constrained for movement together in unison with movement of the first lift wheel arm independently of rockshaft structure;
• third and fourth lift cylinders having rod and base ends, the third and fourth cylinders connected to the second lift wheel arm and constrained for movement together in unison;
• wherein the first and second cylinders are connected in parallel and are connected to the fourth cylinder and to a source of hydraulic fluid under pressure for extending and retracting the first, second and fourth cylinders;
• means hydraulically connecting the first cylinder with the third cylinder to thereby synchronize the movement of the first and second cylinders with the third and fourth cylinders independently of any mechanical linkage between the first and second lift wheel arms;
• a plurality of wing lift cylinders connected to outer wing frames, and means connecting the wing lift cylinders for operation in series with two of the first, second, third and fourth cylinders to move the main frame and the wing frames vertically generally in unison;
• and
• an outer frame fold cylinder structure and fold circuit for operating the frame fold cylinder structure to fold the outer wing frames between field-working and transport positions. and means for selectively connecting the fold circuit to the wing lift cylinders to operate the wing lift cylinders during folding:
• wherein the means for selectively connecting the fold circuit to the wing lift cylinders includes valve structure selectively connecting wing cylinders to the fold circuit for retracting the wing cylinders when the frame fold cylinder structure is operated.

A hydraulic lift system for a multi-sectioned agricultural implement having a main frame and outer wing frames movably connected to the main frame, the lift system comprising:

• first and second individually mounted lift wheel arms connected to the main frame;
• first and second lift cylinders having rod and base ends, and means connecting the first and second lift cylinders to the first lift wheel arm for movement together in unison with the first lift wheel arm independently of rockshaft structure between the first and second lift cylinders;
• third and fourth lift cylinders having rod and base ends, the third and fourth cylinders connected to the second lift wheel arm and constrained for movement together in unison;
• means connecting the first and second lift cylinders in parallel;
• means for hydraulically synchronizing the movement of the first and second cylinders with the third and fourth cylinders independently of any mechanical linkage between the first and second lift wheel arms;
• a plurality of wing lift cylinders connected to outer wing frames;
• means for connecting the wing lift cylinders in series with at least one of the first, second, third and fourth cylinders;
• and
• further comprising wing frame fold cylinders, and a hydraulic fold control circuit for activating the fold cylinders to move the wing frames to a transport position, and means for selectively connecting the fold control circuit to the wing lift cylinders to move the wing lift cylinders to a retracted position with folding of the wing frames to the transport position.

A hydraulic lift system for a multi-sectioned agricultural implement having a main frame and foldable outer wing frames connected to the main frame for movement to and from a field-working position, the lift system comprising:

• first and second lift wheel arms connected to the main frame;
• main frame lift cylinders connected to the first and second lift arms for raising and lowering the lift arms with respect to the main frame;
• wing frame wheel arms connected to the outer wing frames;
• wing frame lift cylinders connected to the wing frame wheel arms for raising and lowering the outer wing frames in the field-working position;
• hydraulic lines connecting the wing frame lift cylinders and the main frame lift cylinders for operation generally in unison;
• a plurality of wing fold cylinders connected to outer wing frames;
• first selective control valve structure connected to the main frame lift cylinders and wing frame lift cylinders for raising and lowering of the main frame and wing frames when in the field-working position;
• second selective control valve structure connected to the wing fold cylinders for folding and unfolding the outer wing frames;
• automatic valve structure connected to the second selective control valve structure and the wing frame lift cylinders for automatically operating the wing frame lift cylinders independently of the first selective control valve structure as the wing frames move from the field-working position to cause the wing frame wheel arms to move to a non-interfering position;
• wherein the main frame lift cylinders comprise first and second pairs of cylinders, the first pair of cylinders connected to a single one of the lift arms and constrained for operation in unison with movement of the single one of the lift arms independently of rockshaft structure;
• and
• wherein the automatic valve structure includes an electrohydraulic valve responsive to the folding of the wing frames to hydraulically connect the wing frame lift cylinders to the wing fold cylinders to move the wing lift cylinders to a retracted position with folding of the wing frames to the transport position.