The present disclosure relates to a hydraulic steering device for an agricultural work vehicle comprising a steering pump for supplying working fluid; an automatic steering unit which is connected to the steering pump, and which changes, according to automatic steering performed by a control part, the traveling direction of the agricultural work vehicle by using the working fluid supplied from the steering pump; a manual steering unit which is connected to each of the steering pump and the automatic steering unit, and which changes, according to manual steering performed by the operation of a steering wheel, the traveling direction of the agricultural work vehicle, and a manual switching unit connected to each of the steering pump and the manual steering unit.

The present disclosure relates to a hydraulic steering device of an agricultural work vehicle comprising a steering pump for supplying a working fluid; an automatic steering unit which uses the working fluid to change the traveling direction of the agricultural work vehicle when automatic steering is performed by a control unit; a manual steering unit which uses the working fluid to change the traveling direction of the agricultural work vehicle when manual steering is performed by operating a steering handle; and an automatic cut-off unit which is for selectively cutting off the supply of the working fluid for the automatic steering to a steering cylinder of the agricultural work vehicle according to whether the manual steering is performed.

The present disclosure provides a steering system of an engineering vehicle, and a backhoe loader. The steering system includes: a direction control device, including a steering wheel, a steering cylinder and steerable wheels, the steering cylinder being in transmission connection with the steering wheel and the steerable wheels; a displacement sensor configured to detect a piston displacement of the steering cylinder; a return motor in transmission connection with the steerable wheels to drive the steerable wheels to return to a normal position; and a controller in signal connection with the displacement sensor and the return motor, and configured to output a control signal according to the piston displacement detected by the displacement sensor to manipulate the return motor to drive the steerable wheels to return. The backhoe loader includes the steering system.

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.

The present application provides a full hydraulic synchronous steering system for a low-speed heavy-load vehicle, where the system includes: a steering control mechanism and a steering actuator; by determining a desired steering curve between a steering wheel angle and a rear wheel angle, when a steering error exceeds an allowable error, a controller controls the opening and closing of an oil replenishment solenoid valve (5) and an oil discharge solenoid valve (4) to adjust an flow rate of the oil flowing into a steering cylinder (7), so as to ensure that the steering error is within an allowable error range, thereby implementing synchronous steering. A method for manipulating the full hydraulic synchronous steering system is further provided. The full hydraulic synchronous steering system and the method can improve synchronous steering capability of the low-speed heavy-load vehicle and change a steering ratio, thereby improving safety and direction feeling of a driver.

In the event of a malfunction in the supply of hydraulic fluid to the a braking device actuating device a hydraulic system has a manually actuated emergency-operation valve arrangement which is formed in such a way that, after the manual actuation thereof, a fluid connection is created between a steering device actuating device and the a pressure chamber of the braking device actuating device. The emergency-operation valve arrangement has a valve block in which flow paths are formed which can be shut off by means of shut-off screws.

In the event of a malfunction in the supply of hydraulic fluid to the a braking device actuating device a hydraulic system has a manually actuated emergency-operation valve arrangement which is formed in such a way that, after the manual actuation thereof, a fluid connection is created between a steering device actuating device and the a pressure chamber of the braking device actuating device. The emergency-operation valve arrangement has a valve block in which flow paths are formed which can be shut off by means of shut-off screws.

A hydraulic steering arrangement (1) is described comprising a supply port arrangement (P, T) having a pressure port (P) and a tank port (T), a working port arrangement having two working ports (L, R), a main flow path (2) having a main orifice (A.sub.1), at least one further orifice (A.sub.2, A.sub.3, A.sub.4) downstream the main orifice (A.sub.1), and a measuring motor (3), the main flow path (2) being arranged between the pressure port (P) and the working port arrangement (L, R), a return flow path (4) arranged between the working port arrangement (L, R) and the tank port (T), an amplification flow path (6) having an amplification orifice (A.sub.U) and being arranged between the pressure port (P) and the working port arrangement (L, R), and an adjustable pressure source (9) connected to the pressure port (P) and having a load sensing port (18), wherein a main drain orifice (A.sub.md) is connected between the main flow path (2) downstream the main orifice (A.sub.1) and the return flow path (4). It should be possible to operate such a steering arrangement with a dynamic flow. To this end a flow divider (19) connects the load sensing port (18) with the main flow path (2) downstream the main orifice (A.sub.1) and the amplification flow path (6) downstream the amplification orifice (A.sub.U).

A steering method for an industrial truck. The industrial truck includes a pivot plate which is mounted to be rotatable about a steering axis in two steering directions, three wheels, one of the three wheels being designed as a central wheel which is rotatably mounted about an axis of rotation in the pivot plate, and a hydraulic cylinder which rotates the pivot plate about the steering axis. The method includes exerting steering forces of at least approximately equal magnitude on the pivot plate to provide a rotation about the steering axis in each of the two steering directions.