A valve for hydraulic parallel work systems is provided. The valve includes a first pair of ports, a second pair of ports, a first connection, and a second connection. The first connection is between the first pair of ports when the valve is in a load reaction-enabling state. The first connection transmits a load reaction from a load at a steering actuator to a steering device of a hydrostatic steering circuit. The second connection is between the second pair of ports when the valve is in an electro-hydraulic steering enabling state. The second connection fluidly connects a fluid source to an electro-hydraulic steering circuit.

The present invention relates to a steering control system and method for a vehicle, and more particularly a control system and method for accurately controlling the lateral movement of an autonomous vehicle that has a non-linear steering system, e.g., a hydraulic steering system, which includes measuring wheel angles of the vehicle, calculating the actuation value for the desired wheel angle based on the measured wheel angle, and rotating the steering wheel according to the actuation value; wherein the actuation values are calculated based on a function f( ) representing the nonlinear behavior of the steering ratio depending on the position and movement direction of the steering wheel, and another function g( ) representing a response lag when the steering direction is changed.

A method of operating a steering system having a rotatable steering control, a steering actuator having a rod movable along a range of travel, a rotary device coupled to the steering control, and a valve assembly disposed between the rotary device and the steering actuator includes rotating the steering control in a first direction, displacing the rod toward an end of the range of travel, and determining when the rod reaches the end of the range of travel. The method also includes, after determining, actuating the valve assembly from a first position in which the rotary device is not in fluid communication with the steering actuator, to a second position in which the rotary device is in fluid communication with the steering actuator, and inhibiting further rotation of the steering control in the first direction due to back pressure on the rotary device.

A method of controlling a work machine having at least one wheel includes providing a controller, an operator control, and a steering system including a steering wheel position sensor, a road wheel angle sensor, a speed sensor, and a feedback device. The method includes detecting a change in steering wheel position via the steering wheel position device and a wheel speed of the at least one wheel via the speed sensor. A predicted lateral acceleration is calculated by the controller as a function of wheel speed and a feedback torque is determined by the controller as a function of the predicted lateral acceleration. The feedback torque is determined from a plurality of feedback torque curves stored by the controller, where each of the plurality of feedback torque curves corresponds to a sensitivity level selectable from the operator control. The feedback torque is commanded to the feedback device.

A steering system for controlling an agricultural machine having a pair of front wheels and a pair of rear wheels includes a controller, an operator steer input for communicating a steer command, a steer input sensor for detecting and outputting the steer command to the controller, a primary differential steering system for operably controlling the pair of front wheels, and a secondary steering system for operably controlling the pair of rear wheels. The secondary steering system includes a first actuator for controlling a first rear wheel and a second actuator for controlling a second rear wheel. The primary differential steering system is controlled based on the steer command. The controller outputs a control signal to operably actuate the first and second actuators at a non-linear steering gain rate as a function of the steer command.

A hydraulic arrangement for distributing a fluid in pressure coming from a source among multiple hydraulic units of a work vehicle. At least one of the hydraulic units provides an electronic load sensing signal and of the hydraulic units provides a hydraulic load sensing signal. The hydraulic arrangement includes a priority valve configured to divide the flow of fluid between the hydraulic units. The priority valve and source are hydraulically controlled by a first hydraulic load sensing signal resulting as the greatest of a plurality of hydraulic load pressure signals taken from the hydraulic unit. The hydraulic arrangement also includes a conversion unit configured to transform an electronic load sensing signal of at least one of the hydraulic units in an equivalent hydraulic load sensing signal so as to define the first hydraulic load sensing signal.

The disclosure relates to an electro-hydraulic control system for directing fluid to at least one hydraulic actuator, the system comprising at least one electronic controller; first and second pilot valves being electrically connected to the at least one electronic controller which is arranged to control the operation of the first and second pilot valves, third and fourth pilot valves being electrically connected to the at least one electronic controller which is arranged to control operation of the third and fourth pilot valves. A pilot operated main valve is configured to control fluid flow to at least one hydraulic actuator. Each of the first and second pilot valves and the third and fourth pilot valves is a fail-safe pilot valve arranged to drain a regulated outlet port to a low pressure reservoir if a spool of the fail-safe pilot valve becomes stuck in an open state.

A hybrid hydro-mechanical/electronic steering system for a track vehicle, where the driver system can simultaneously use hydro-mechanical connections and electronic (steer by wire) connections to steer a track vehicle such as a tank, where safeguards for safety and reliability include seamless transition between electronic to hydro-mechanical control and vice versa, such that the system can be used in a single or double chassis track vehicle and is adaptable for autonomous driving.

A redundant steering system comprises a primary power source; a secondary power source; first and second pumps operatively coupled to the primary and secondary power sources, respectively, to output first and second supplies of hydraulic fluid to a steering cylinder based on operation of the primary and secondary power source, respectively; first and second pairs of selector valves respectively coupled to the first and second pumps; and a charge circuit coupled to respective control inputs of the first and second pairs of selector valves to selectively supply hydraulic fluid to the control inputs of the first and second pairs of selector valves to stop hydraulic fluid from only one of the first pump and the second pump from being provided to the steering cylinder and to provide hydraulic fluid to the steering cylinder from only one of the other of the first pump and the second pump.

A hydraulic steering device hydraulically connects a steering cylinder to a supply system, wherein the supply system can be operatively connected hydraulically to the steering cylinder via a steering valve in order to configure a main flow connection, and the supply system can be operatively connected hydraulically to the steering cylinder via a flow control valve arrangement in order to configure an auxiliary flow connection which bypasses the main flow direction.