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A system and method for interrupting a Global Navigation Satellite System (GNSS)-based automatic steering mode of a hydraulic steering system on a vehicle. When a steering wheel is manually turned by an operator, pressurized hydraulic fluid from a steering directional control valve activates an inte

A system and method for interrupting a Global Navigation Satellite System (GNSS)-based automatic steering mode of a hydraulic steering system on a vehicle. When a steering wheel is manually turned by an operator, pressurized hydraulic fluid from a steering directional control valve activates an interrupter having an interrupter valve. The interrupter valve blocks pressurized fluid flow to the automatic steering system, thus overriding automatic steering and giving the operator full manual steering control via the steering wheel. The hydraulic interrupt system is mechanical with no electronic elements.

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1. A steering interrupt system for a vehicle, which vehicle includes steerable wheels, a hydraulic steering system with a pressurized fluid source, a steering directional control valve connected to the pressurized fluid source, a steering wheel connected to the steering directional control valve, a

1. A steering interrupt system for a vehicle, which vehicle includes steerable wheels, a hydraulic steering system with a pressurized fluid source, a steering directional control valve connected to the pressurized fluid source, a steering wheel connected to the steering directional control valve, a steering actuator selectively connected to the pressurized fluid source via the steering directional control valve, and an automatic steering system automatically controlling the steering actuator in an automatic steering mode, the steering interrupt system comprising: a load sensor connected to the steering directional control valve; andan interrupt valve connected to the steering directional control valve and the load sensor, the interrupt valve configured to switch from a first state in the automatic steering mode to a second state in an interrupt mode and block pressurized fluid flow from the automatic steering system to the steering actuator based on a fluid pressure load sensed by the load sensor from turning of the steering wheel by an operator, wherein during the interrupt mode:the steering directional control valve provides pressurized hydraulic fluid to the steering actuator and to control the steerable wheels in proportion to movement of the steering wheel by the operator; andthe interrupt valve is configured to switch from the second state during the interrupt mode back to the first state in the automatic steering mode and unblock the pressurized fluid flow to the steering actuator based on the fluid pressure load sensed by the load sensor indicating the steering wheel is released by the operator. 2. The steering interrupt system according to claim 1, wherein the automatic steering system includes a Global Navigation Satellite System (GNSS)-based positioning system. 3. The steering interrupt system according to claim 1, wherein the steering actuator includes a piston-and-cylinder unit. 4. The steering interrupt system according to claim 1, wherein the hydraulic steering system includes a closed center hydraulic circuit. 5. The steering interrupt system according to claim 1, wherein the hydraulic steering system includes an open center hydraulic circuit. 6. A steering interrupt system for a vehicle, which vehicle includes steerable wheels, a hydraulic steering system with a pressurized fluid source, a steering directional control valve connected to the pressurized fluid source, a steering wheel connected to the steering directional control valve, a steering actuator selectively connected to the pressurized fluid source via the steering directional control valve, and an automatic steering system to automatically control the steering actuator in an automatic steering mode, the steering interrupt system comprising: an interrupt valve connected to the steering directional control valve configured to switch from the automatic steering mode to an interrupt mode where the interrupt valve interrupts pressurized fluid flow to the steering actuator and the steering directional control valve provides pressurized hydraulic fluid to the steering actuator, wherein:the interrupt valve is spring-loaded;the spring of the interrupt valve is configured to expand in the automatic steering mode maintaining an open position allowing the pressurized fluid flow therethrough; andthe spring of the interrupt valve is configured to compress in the interrupt mode, closing the interrupt valve and blocking the pressurized fluid flow. 7. A steering interrupt system, comprising: a steering priority valve selectively connecting a pump for a pressurized fluid source to a steering directional control valve;a solenoid-actuated valve connected to the pressurized fluid source and activated by an automatic steering system;a pressure-compensating valve connected to the pressurized fluid source;a proportional flow control directional valve connected to the pressurized fluid source and operated by the automatic steering system;a pair of load-holding valves connected between the proportional flow control directional valve and a steering actuator;a shuttle valve connected between the load-holding valves and the proportional flow control directional valve; andan interrupt valve connected to the steering directional control valve and the steering priority valve configured to block pressurized fluid flow to the steering actuator based on the steering directional control valve indicating manual turning of a steering wheel. 8. A steering interrupt system for a vehicle, comprising: an interrupt valve connected to a steering directional control valve and configured to interrupt pressurized fluid flow in a hydraulic steering system to a steering actuator when a steering wheel is turned by an operator; anda load sensor connected to the steering directional control valve, a load sense shuttle valve, and the interrupt valve, wherein:the load sensor is configured to sense a fluid pressure load resulting from the operator turning the steering wheel; andthe interrupt valve is configured to interrupt the pressurized fluid flow in response to the fluid pressure load sensed by the load sensor. 9. The steering interrupt system according to claim 1, wherein the hydraulic steering system further comprises: a fluid tank; andan excess flow line configured for selectively diverting excess pressurized fluid from the steering directional control valve to the fluid tank. 10. A hydraulic steering system for a vehicle, comprising: a steering directional control valve coupled between a steering wheel and a steering actuator;a load sensor connected to the steering directional control valve; andan interrupt valve connected to the steering directional control valve and the load sensor and configured to block pressurized fluid flow to a steering actuator based on a fluid pressure load sensed by the load sensor from manual turning of the steering wheel, wherein;the steering directional control valve is configured to control the steering actuator while the interrupt valve blocks the pressurized fluid flow to the steering actuator; andthe interrupt valve is configured to unblock the pressurized fluid flow from to the actuator based on the fluid pressure load sensed by the load sensor indicating the steering wheel is released by said operator. 11. The hydraulic steering system according to claim 10, further comprising: a Global Navigation Satellite System (GNSS)-based positioning system connected to the steering actuator; andwherein an automatic steering mode of the hydraulic steering system is controlled by the GNSS-based positioning system. 12. The hydraulic steering system according to claim 10, wherein the steering actuator includes a piston-and-cylinder unit. 13. The hydraulic steering system according to claim 10, further comprising a closed center hydraulic circuit. 14. The hydraulic steering system according to claim 10, further comprising an open center hydraulic circuit. 15. A hydraulic steering system for a vehicle, comprising: a steering directional control valve coupled between a steering wheel and a steering actuator; andan interrupt valve connected to the steering directional control valve and configured to block pressurized fluid flow to the steering actuator in response to manual turning of the steering wheel, wherein;the steering directional control valve is configured to control the steering actuator while the interrupt valve blocks the pressurized fluid flow to the steering actuator;the interrupt valve is configured to unblock the pressurized fluid flow to the steering actuator when the steering wheel is released by the operator;the interrupt valve is spring-loaded;the spring of the spring-loaded interrupt valve is configured to expand maintaining an open position allowing the pressurized fluid flow therethrough; andthe spring of the spring-loaded interrupt valve is configured to compress closing the spring-loaded interrupt valve and block the pressurized fluid flow. 16. A hydraulic steering system for a vehicle, comprising: a steering directional control valve coupled between a steering wheel and a steering actuator;an interrupt valve connected to the steering directional control valve and configured to block pressurized fluid flow in a hydraulic steering system to the steering actuator in response to a sensed manual turning of the steering wheel by the steering directional control valve; anda steering priority valve coupling a pump to the steering directional control valve to control the steering actuator while the interrupt valve blocks the pressurized fluid flow. 17. The hydraulic steering system according to claim 10, wherein the interrupt valve is configured to close in response to the fluid pressure load sensed by the load sensor. 18. The hydraulic steering system according to claim 16, further comprising: a fluid tank; andan excess flow line configured to selectively divert excess pressurized fluid from the steering directional control valve to the fluid tank. 19. A hydraulic steering system for a vehicle including steerable wheels, comprising: a steering directional control valve selectively connecting a pressurized fluid source to a steering actuator;an interrupt valve connected to the steering directional control valve and configured to block pressurized fluid flow to the steering actuator; anda steering priority valve selectively connecting a pump to the steering directional control valve based on a load sense line connected between the steering directional control valve and the interrupt valve indicating manual operation of a steering wheel, wherein:the steering wheel is configured to control steerable wheels via the steering directional control valve and the steering actuator during the manual operation of the steering wheel, andthe hydraulic steering system is configured to switch to an automatic steering mode where an auto-steering system controls the steering actuator and the steerable wheels when the load sense line indicates termination of the manual operation of the steering wheel. 20. The hydraulic steering system according to claim 19, further comprising a closed center hydraulic circuit including a load sensor connected to the steering directional control valve and a load sense shuttle valve, the load sensor configured to activate the interrupt valve based on a sensed fluid pressure load resulting from the manual turning of the steering wheel. 21. The hydraulic steering system according to claim 19, further comprising an open center hydraulic circuit including: a fluid tank connected to the steering directional control valve; andan excess flow line configured for selectively diverting excess pressurized fluid through the steering directional control valve to the fluid tank. 22. A method of interrupting automatic steering of a vehicle, comprising: operating a hydraulic steering system in an automatic steering mode where an automatic steering system automatically controls a steering actuator and steers wheels connected to the steering actuator;sensing an operator turning a steering wheel;sensing with a load sensor a fluid pressure load from a steering directional control valve;activating an interrupt valve when the sensed fluid pressure load indicates manual operation of the steering wheel;blocking with the activated interrupt valve pressurized fluid flow from the automatic steering system to the steering actuator;directing with the steering directional control valve pressurized fluid to the steering actuator to control the steerable wheels in proportion to manual movement of steering wheel by the operator;deactivating the interrupt valve when the sensed fluid pressure load from the load sensor indicates termination of the manual operation of the steering wheel;allowing with the deactivated interrupt valve fluid flow from the automatic steering system said back to the steering actuator and reactivation of the automatic steering mode; andoperating the hydraulic steering system back in the automatic steering mode where the automatic steering system automatically controls the steering actuator and steers the wheels. 23. The method according to claim 22, wherein the automatic steering system includes a Global Navigation Satellite System (GNSS)-based positioning system. 24. The method according to claim 22, wherein the steering actuator includes a piston-and-cylinder unit. 25. The method according to claim 22, wherein the hydraulic steering system includes a closed center hydraulic circuit. 26. The method according to claim 22, wherein the hydraulic steering system includes an open center hydraulic circuit. 27. The method according to claim 22, wherein the hydraulic steering system further comprises: a pressurized fluid source including a pump;a steering priority valve selectively connecting the pump and the steering directional control valve;a solenoid-actuated valve connected to the pressurized fluid source and activated by the automatic steering system;a pressure-compensating valve connected to the pressurized fluid source;a proportional flow control directional valve connected to the pressurized fluid source and operated by the automatic steering system;a pair of load-holding valves connected to the proportional flow control directional valve and the steering actuator; anda shuttle valve connected to the load-holding valves and the proportional flow control directional valve. 28. The method according to claim 27, wherein: the interrupt valve is spring-loaded and a spring of the spring-loaded interrupt valve compresses, closing the interrupt valve in an interrupt mode;the pump displaces the pressurized fluid through the steering directional control valve;the steering priority valve sends an override signal to the automatic steering system in the interrupt mode;the spring of the spring-loaded interrupt valve expands opening the interrupt valve in the automatic steering mode;the solenoid-actuated valve controls pressurized fluid flow in the automatic steering mode as directed by the automatic steering system;the pressure-compensating valve maintains fluid flow pressure;the proportional flow control directional valve controls the directional flow of the pressurized fluid to the load-holding valves as directed by the automatic steering system;the load-holding valves control pressurized fluid flow to the steering actuator; andthe shuttle valve prevents backflow of fluid from the load-holding valves back to the proportional flow control directional valve. 29. The method according to claim 22, wherein: the load sensor includes a load sense shuttle valve configured to sense the fluid pressure load resulting from manual operation of the steering wheel; andthe interrupt valve is configured to close in response to the sensed fluid pressure load by the load sensor. 30. The method according to claim 29, further comprising: the interrupt valve closing in response to the sensed fluid pressure load by the load sensor; andthe load sense shuttle valve triggering a change in fluid flow pressure and preventing pressurized fluid flow to the automatic steering system. 31. The method according to claim 22, wherein the hydraulic steering system further comprises: a fluid tank; andan excess flow line configured to divert excess pressurized fluid from the steering directional control valve to the fluid tank. 32. The method according to claim 31, further comprising: maintaining with the steering directional valve pressurized fluid flow from the hydraulic steering system to the steering actuator; anddiverting excess pressurized fluid from the hydraulic steering system to the fluid tank.