Electrohydraulic control of implement lift cylinders

In an agricultural implement having a transversely extending, tool-supporting frame with a forward portion and an aft portion and adapted for movement forwardly over the ground by a towing vehicle and supported by a plurality of transversely spaced lift assemblies for raising and lowering the frame relative to the ground, a lift control system comprising:

• hydraulic cylinders connected to the lift assemblies;
• control valve structure connected to the hydraulic cylinders and to a source of hydraulic fluid under pressure, the control valve structure selectively operable to extend and retract the hydraulic cylinders to operate the lift assemblies to raise and lower the frame;
• transducer members responsive to operation of the lift assemblies and providing output signals dependent upon the position of the frame;
• an electronic control unit connected to the control valve structure and the transducer members and responsive to the transducer output signals to individually operate the hydraulic cylinders for positioning the frame at a preselected position relative to the ground;
• and
• wherein the control unit includes an offset control to maintain selected portions of the frame at different positions relative to each other, including a tilt control for adjusting the forward portion of the frame relative to the aft portion of the frame.

In an agricultural implement having a transversely extending, tool-supporting frame with a forward portion and an aft portion and adapted for movement forwardly over the ground by a towing vehicle and supported by a plurality of transversely spaced lift assemblies for raising and lowering the frame relative to the ground, a lift control system comprising:

• hydraulic cylinders connected to the lift assemblies;
• control valve structure connected to the hydraulic cylinders and to a source of hydraulic fluid under pressure, the control valve structure selectively operable to extend and retract the hydraulic cylinders to operate the lift assemblies to raise and lower the frame;
• transducer members responsive to operation of the lift assemblies and providing output signals dependent upon the position of the frame;
• an electronic control unit connected to the control valve structure and the transducer members and responsive to the transducer output signals to individually operate the hydraulic cylinders for positioning the frame at a preselected position relative to the ground;
• and
• including a first depth control and an intermediate depth control, the first depth control selecting a normal field condition operating depth, and the intermediate control selecting a second depth offset from the normal field condition operating depth.

In an agricultural implement having a transversely extending, tool-supporting frame with a forward portion and an aft portion and central and side sections, the frame adapted for movement forwardly over the ground by a towing vehicle and supported by a plurality of transversely spaced lift assemblies for raising and lowering the central and side sections relative to the ground including central lift wheel assemblies providing support for the central section, a lift control system comprising:

• hydraulic cylinders connected to the lift assemblies including central lift wheel cylinders connected to the central lift wheel assemblies;
• control valve structure connected to the hydraulic cylinders and to a source of hydraulic fluid under pressure, the control valve structure selectively operable to extend and retract the hydraulic cylinders to operate the lift assemblies to raise and lower the frame;
• transducer members responsive to operation of the lift assemblies and providing output signals dependent upon the position of the frame;
• an electronic control unit connected to the control valve structure and the transducer members and responsive to the transducer output signals to individually operate the hydraulic cylinders and position the frame at a preselected position relative to the ground including a first offset control for adjusting the depth of penetration of tools carried by the central section relative to the depth of penetration tools carried by at least one of the side sections, and a second offset control providing adjustment of the central lift wheel assemblies relative to each other.

In an implement adapted for forward movement over the ground and including a transversely extending frame supporting earthworking tools, lift wheel assemblies supported from the frame and selectively positionable to raise and lower the tools between raised transport positions and lowered field-working positions and to vary the location of the earthworking tools when the tools are in a field-working position, the lift wheel assemblies including individual lift motors, a lift control comprising:

• electrohydraulic valve structure connected to the lift motors;
• a source of hydraulic fluid under pressure selectively connectable to the electrohydraulic valve structure;
• transducers associated with the lift motors and providing transducer signals dependent on the position of each of the lift assemblies;
• an operator control unit (OCU) for providing desired position signals;
• an implement control unit (ICU) having inputs connected to the transducers and to the OCU, and outputs connected to the electrohydraulic valve structure, wherein the ICU is responsive to the transducer signals and desired position signals for controlling the valve structure to individually control the lift motors and maintain the tools at desired positions relative to the ground;
• wherein the OCU includes controls for selectively varying the position of the tools adjacent one of the lift wheel assemblies relative to the position of the tools adjacent another of the lift wheel assemblies;
• and
• further including a level reference control providing level reference signals to the ICU corresponding to a preselected level condition of the frame.