Electro-hydraulic steering control system

A method of directing fluid to steering actuators on a work machine, comprising:

• selectively directing fluid through a main valve to the steering actuators, the main valve controlling fluid flow to the steering actuators;
• selectively directing fluid through left and right primary steering valves to the main valve, the fluid through the left and right primary steering valves affecting the main valve to control fluid flow to the steering actuators;
• selectively directing fluid through left and right redundant steering valves to the main valve, the fluid through the left and right redundant steering valves affecting the main valve to control fluid flow to the steering actuators;
• and
• directing fluid from at least one of the left and right primary steering valves through a shuttle valve operably disposed between one of:
• the right primary and the right secondary steering valves;
• and
• the left primary and the left secondary steering valves, the fluid through the shuttle valve affecting the main valve to control fluid flow to the steering actuators.

A work machine, comprising:

• front and rear ground engaging devices;
• steering actuators configured to turn one of the front and rear ground engaging devices relative to the other of the front and rear ground engaging devices;
• a main valve in fluid communication with the steering actuators and configured to control fluid flow to the steering actuators;
• a primary pilot system including left and right primary steering pilot valves in communication with the main valve and configured to provide fluid pressure to affect the main valve to control fluid flow to the steering actuators;
• a redundant pilot system including left and right redundant steering pilot valves in communication with the main valve and configured to provide fluid pressure to affect the main valve to control fluid flow to the steering actuators;
• and
• a right and a left shuttle valve, the right shuttle valve being disposed between the right primary steering pilot valve and the right redundant steering pilot valve and the left shuttle valve being disposed between the left primary steering pilot valve and the left redundant steering pilot valve, the right shuttle valve being operable to selectively control fluid from the right primary steering pilot valve and the right redundant steering pilot valve to the main valve to control the main valve, and
• the left shuttle valve being operable to selectively control fluid from the left primary steering pilot valve and the left redundant steering pilot valve to the main valve to control the main valve.

A work machine, comprising:

• front and rear ground engaging devices;
• steering actuators configured to turn one of the front and rear ground engaging devices relative to the other of the front and rear ground engaging devices;
• a main valve in fluid communication with the steering actuators and configured to control fluid flow to the steering actuators;
• a primary pilot valve in communication with the main valve and configured to provide fluid pressure to affect the main valve to control fluid flow to the steering actuators;
• a redundant pilot valve in communication with the main valve and configured to provide fluid pressure to affect the main valve to control fluid flow to the steering actuators;
• an on-off valve disposed to selectively allow or block fluid flow to the primary pilot valve;
• and
• an electronic control system configured to detect a fault related to the primary pilot valve and configured to actuate the on-off valve to block fluid flow to the primary pilot valve when the fault is detected.

A work machine, comprising:

• front and rear ground engaging devices;
• steering actuators configured to turn one of the front and rear ground engaging devices relative to the other of the front and rear ground engaging devices;
• a main valve in fluid communication with the steering actuators and configured to control fluid flow to the steering actuators;
• a fluid source operable to selectively provide pressurized fluid to the main valve;
• left and right primary steering pilot valves in communication with the main valve and the fluid source and configured to provide fluid pressure to affect the main valve to control fluid flow to the steering actuators;
• a primary pressure reducing valve operably disposed between the fluid source and the left and right primary steering pilot valves;
• left and right redundant steering pilot valves in communication with the main valve and the fluid source and configured to provide fluid pressure to affect the main valve to control fluid flow to the steering actuators;
• and
• a redundant pressure reducing valve operably disposed between the fluid source and the left and right redundant steering pilot valves.