A hydraulic steering arrangement (1) is disclosed. The hydraulic steering arrangement (1) includes 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) and at least one further orifice (A.sub.2, A.sub.3, A.sub.4) downstream the main orifice (A.sub.1), 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), a measuring motor (3), an amplification flow path (6) having an amplification orifice (AU) 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.drain) is connected between the main flow path (2) down-stream the main orifice (A.sub.1) and the return flow path (4). Such a steering arrangement should have the possibility of dynamic steering with a simple construction. To this end a dynamic main orifice (A.sub.1-dyn) is connected between the load sensing port (18) and the main flow path (2) downstream the main orifice (A.sub.1), and a dynamic drain orifice (Adrain-dyn) is connected between the load sensing port (18) and the return flow path (4), which dynamic drain orifice (Adrain-dyn) is open when the dynamic main orifice (A1-dyn) is closed.

A hydraulic steering arrangement (1) is disclosed. The hydraulic steering arrangement (1) includes 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) and at least one further orifice (A.sub.2, A.sub.3, A.sub.4) downstream the main orifice (A.sub.1), 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), a measuring motor (3), an amplification flow path (6) having an amplification orifice (AU) 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.drain) is connected between the main flow path (2) down-stream the main orifice (A.sub.1) and the return flow path (4). Such a steering arrangement should have the possibility of dynamic steering with a simple construction. To this end a dynamic main orifice (A.sub.1-dyn) is connected between the load sensing port (18) and the main flow path (2) downstream the main orifice (A.sub.1), and a dynamic drain orifice (Adrain-dyn) is connected between the load sensing port (18) and the return flow path (4), which dynamic drain orifice (Adrain-dyn) is open when the dynamic main orifice (A1-dyn) is closed.

A pressure relief valve for a fluid power assist steering system. The valve includes a housing and a spool disposed in the housing. The spool defines a cavity and has a first end and a second end. The spool is movable in the housing to limit an output pressure of the pump. A poppet seat is secured to the second end of the spool. A poppet is disposed in the cavity. A poppet spring biases the poppet into engagement with the poppet seat. A set screw is received in the first end of the spool. The set screw is rotatable relative to the spool to adjust a compression level of the poppet spring.

A pressure relief valve for a fluid power assist steering system. The valve includes a housing and a spool disposed in the housing. The spool defines a cavity and has a first end and a second end. The spool is movable in the housing to limit an output pressure of the pump. A poppet seat is secured to the second end of the spool. A poppet is disposed in the cavity. A poppet spring biases the poppet into engagement with the poppet seat. A set screw is received in the first end of the spool. The set screw is rotatable relative to the spool to adjust a compression level of the poppet spring.

An articulated work vehicle with linked front and rear frames includes a joystick lever, a force imparting component, and a controller. The joystick lever can be moved to an inside or an outside with respect to an operator's seat by being operated by an operator, to change a steering angle of the front frame with respect to the rear frame. The force imparting component is configured to impart an assist force or a counterforce to an operation of the joystick lever by the operator. The controller controls the force imparting component so that an operating force required to move the joystick lever to the outside is different from an operating force required to move the joystick lever to the inside.

An articulated work vehicle with linked front and rear frames includes a joystick lever, a force imparting component, and a controller. The joystick lever can be moved to an inside or an outside with respect to an operator's seat by being operated by an operator, to change a steering angle of the front frame with respect to the rear frame. The force imparting component is configured to impart an assist force or a counterforce to an operation of the joystick lever by the operator. The controller controls the force imparting component so that an operating force required to move the joystick lever to the outside is different from an operating force required to move the joystick lever to the inside.

A pressure relief valve for a fluid power assist steering system. The valve includes a housing and a spool disposed in the housing. The spool defines a cavity and has a first end and a second end. The spool is movable in the housing to limit an output pressure of the pump. A poppet seat is secured to the second end of the spool. A poppet is disposed in the cavity. A poppet spring biases the poppet into engagement with the poppet seat. A set screw is received in the first end of the spool. The set screw is rotatable relative to the spool to adjust a compression level of the poppet spring.

A pressure relief valve for a fluid power assist steering system. The valve includes a housing and a spool disposed in the housing. The spool defines a cavity and has a first end and a second end. The spool is movable in the housing to limit an output pressure of the pump. A poppet seat is secured to the second end of the spool. A poppet is disposed in the cavity. A poppet spring biases the poppet into engagement with the poppet seat. A set screw is received in the first end of the spool. The set screw is rotatable relative to the spool to adjust a compression level of the poppet spring.

A fluid controller (1), in particular as part of a hydraulic steering unit, is described, said controller (1) comprising a housing (2) having a supply port arrangement, a sleeve (4) arranged rotatably in a bore of the housing (2), a spool (3) arranged rotatably in the sleeve (4), and a measuring motor, wherein the measuring motor comprises a plurality of working chambers, each working chamber being connected to the bore, wherein the sleeve (4) comprises a commutation geometry (7) having a number of pairs of commutation grooves (12, 13) and controlling together with a housing geometry (5) of the housing (2) a flow of hydraulic fluid into and out of the working chambers and the spool (3) comprises a spool geometry controlling together with a valve geometry of the sleeve (4) a flow of hydraulic fluid between the supply port arrangement and the commutation geometry. Such a fluid controller should have a stable control behaviour. To this end at least one of the commutation grooves (12, 13) comprise a closed bottom and at least one of the commutation grooves (12, 13) comprise a throughgoing opening (10, 11) forming part of the valve geometry.

A fluid controller (1), in particular as part of a hydraulic steering unit, is described, said controller (1) comprising a housing (2) having a supply port arrangement, a sleeve (4) arranged rotatably in a bore of the housing (2), a spool (3) arranged rotatably in the sleeve (4), and a measuring motor, wherein the measuring motor comprises a plurality of working chambers, each working chamber being connected to the bore, wherein the sleeve (4) comprises a commutation geometry (7) having a number of pairs of commutation grooves (12, 13) and controlling together with a housing geometry (5) of the housing (2) a flow of hydraulic fluid into and out of the working chambers and the spool (3) comprises a spool geometry controlling together with a valve geometry of the sleeve (4) a flow of hydraulic fluid between the supply port arrangement and the commutation geometry. Such a fluid controller should have a stable control behaviour. To this end at least one of the commutation grooves (12, 13) comprise a closed bottom and at least one of the commutation grooves (12, 13) comprise a throughgoing opening (10, 11) forming part of the valve geometry.