A hydraulic steering unit (1) is described comprising a supply port arrangement having a pressure port (8) connected to a main flow path (6) and a tank port (T) connected to a tank flow path (7), a working port arrangement having a left working port (L) connected to a left working flow path (9) and a right working port (R) connected to a right working flow path (10), a bridge arrangement (14) of variable orifices having a first left orifice (A2L) connected to the main flow path (6) and to the left working flow path (9), a first right orifice (A2R) connected to the main flow path (6) and to the right working flow path (10), a second left orifice (A3L) connected to the left working flow path (9) and to the tank flow path (7), and a second right orifice (A3R) connected to the right working flow path (10) and to the tank flow path (7). Such a hydraulic steering unit should allow comfortable steering. To this end a measuring motor arrangement is arranged in one of the left working flow path (9) and the right working flow path (10), the measuring motor arrangement (15) having a first measuring motor (16) and a second measuring motor (17).

A hydraulic steering unit (1) is described comprising a supply port arrangement having a pressure port (8) connected to a main flow path (6) and a tank port (T) connected to a tank flow path (7), a working port arrangement having a left working port (L) connected to a left working flow path (9) and a right working port (R) connected to a right working flow path (10), a bridge arrangement (14) of variable orifices having a first left orifice (A2L) connected to the main flow path (6) and to the left working flow path (9), a first right orifice (A2R) connected to the main flow path (6) and to the right working flow path (10), a second left orifice (A3L) connected to the left working flow path (9) and to the tank flow path (7), and a second right orifice (A3R) connected to the right working flow path (10) and to the tank flow path (7). Such a hydraulic steering unit should allow comfortable steering. To this end a measuring motor arrangement is arranged in one of the left working flow path (9) and the right working flow path (10), the measuring motor arrangement (15) having a first measuring motor (16) and a second measuring motor (17).

A steerable, self-propelled vehicle includes a rotatable steering column that is connected to control the steering angle of one or more ground-engaging members of the vehicle. The vehicle includes between the steering column and the ground-engaging member a first steering servomechanism having at least a first steering assistance characteristic; a second steering servomechanism having a second steering assistance characteristic also being connected to act on the steering column. A controller is provided for causing the first and second steering assistance characteristics to influence the steering of the vehicle in dependence on one or more one or more control commands generated in the controller.

A steerable, self-propelled vehicle includes a rotatable steering column that is connected to control the steering angle of one or more ground-engaging members of the vehicle. The vehicle includes between the steering column and the ground-engaging member a first steering servomechanism having at least a first steering assistance characteristic; a second steering servomechanism having a second steering assistance characteristic also being connected to act on the steering column. A controller is provided for causing the first and second steering assistance characteristics to influence the steering of the vehicle in dependence on one or more one or more control commands generated in the controller.

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 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 hydraulic steering unit (1) is described comprising a supply port arrangement having a pressure port (P) connected to a main flow path (2) and a tank port (T) connected to a tank flow path (3), a working port arrangement having a left working port (L) connected to a left working flow path (4) and a right working port (R) connected to a right working flow path (5), a bridge arrangement (7) of variable orifices having a first left orifice (A2L) connected to the main flow path (2) and to the left working flow path (4), a first right orifice (A2R) connected to the main flow path (2) and to the right working flow path (5), a second left orifice (A3L) connected to the left working flow path (4) and to the tank flow path (3), and a second right orifice (A3R) connected to the right working flow path (5) and to the tank flow path (3). Such a hydraulic steering unit should not have a self-alignment but a comfortable feeling for the driver. To this end a variable diagonal orifice A11_12 1 a variable diagonal orifice (A11_12) is connected to the main flow path (2) and to the tank flow path (3), wherein the orifices of the bridge arrangement (7) are closed in neutral position and the diagonal orifice (A11_12) is open in neutral position.

A steering system for a work vehicle having a steerable wheel. The steering system includes a steering input device configured to provide a first steering input and a second steering input to move the steerable wheel. A pilot system is operatively connected to the steering input device and includes a first pilot line operatively connected to the first steering input and a second pilot line operatively connected to the second steering input. A piloted system is operatively connected to the pilot system and includes a direction control valve operatively connected to each of the first and second pilot lines and to a steering cylinder. The steering cylinder is coupled to the steerable wheel. The direction control valve responds to each of the pressure signals of the first and second pilot lines to adjust the position of the steering cylinder which in turn moves the steerable wheel.

A steering system for a work vehicle having a steerable wheel. The steering system includes a steering input device configured to provide a first steering input and a second steering input to move the steerable wheel. A pilot system is operatively connected to the steering input device and includes a first pilot line operatively connected to the first steering input and a second pilot line operatively connected to the second steering input. A piloted system is operatively connected to the pilot system and includes a direction control valve operatively connected to each of the first and second pilot lines and to a steering cylinder. The steering cylinder is coupled to the steerable wheel. The direction control valve responds to each of the pressure signals of the first and second pilot lines to adjust the position of the steering cylinder which in turn moves the steerable wheel.

A hydraulic steering device having a steering actuator (10), which can be actuated by a steering unit (12), and having a flow-regulating valve arrangement (14), which is also used to actuate the steering actuator (10), is disclosed, which is characterized in that the flow-regulating valve arrangement (14) has a discharge valve (V2), which is designed as a proportional servo valve (16), and a directional valve (V3), which, in its unactuated position, blocks the fluid-conveying connection between the discharge valve (V2) and the steering actuator (10) and, in its actuated position, actuates the steering actuator (10) in one or the other steering direction.