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 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).

In a hydraulic system, such as for a tractor or other agricultural vehicle, a main supply pump supplies fluid to a steering system through a steering circuit and a second pump supplies fluid to a cooling fan motor. The second pump is connected with the steering circuit to provide a second a source of fluid to the steering system when the main supply pump is unable to meet demand. A prioritization valve regulates the flow of fluid from the second pump to the motor. The second pump acts as a secondary pump for the steering system and drives a cooling fan.

A hydraulic system of a vehicle includes a first pump for supplying at least one first hydraulic circuit and at least one second pump for supplying at least one second hydraulic circuit with hydraulic medium. The second pump supplies the first hydraulic circuit with hydraulic medium in an emergency mode or when an output pressure of the first pump fails.

A hydraulic rear axle steering for multi-axle vehicles, including a steering cylinder with a piston and two working chambers. The steering cylinder has a mechanical blocking device, which blocks the piston when it reaches a central position within the steering cylinder. The blocking device has a blocking member, which is retained in an engaged position by a locking element in the blocked state. The locking element is movable by a separate, hydraulically actuated actuator between a blocking position and a first unblocking position in which the locking element releases the blocking element. An admission-pressure-controlled load safety valve is provided for each working chamber, and control connections of the valves are connected to a pressure line leading to the respective other working chamber. The actuator is adjusted such that, when a lower, first pressure value is applied, the locking element moves into the unblocking position, and the valves are adjusted such that, when a higher, second pressure value is applied, the valves open towards the tank.

A hydraulic rear axle steering for multi-axle vehicles, including a steering cylinder with a piston and two working chambers. The steering cylinder has a mechanical blocking device, which blocks the piston when it reaches a central position within the steering cylinder. The blocking device has a blocking member, which is retained in an engaged position by a locking element in the blocked state. The locking element is movable by a separate, hydraulically actuated actuator between a blocking position and a first unblocking position in which the locking element releases the blocking element. An admission-pressure-controlled load safety valve is provided for each working chamber, and control connections of the valves are connected to a pressure line leading to the respective other working chamber. The actuator is adjusted such that, when a lower, first pressure value is applied, the locking element moves into the unblocking position, and the valves are adjusted such that, when a higher, second pressure value is applied, the valves open towards the tank.

An auxiliary hydraulic system including an accumulator, a control valve, and a hydraulic connector. The accumulator connects to a primary hydraulic system including a hydraulic pump, a brake circuit, and a steering circuit. The control valve selectively allows or prevents flow from an accumulator to at least one of the brake circuit and the steering circuit. The hydraulic connector selectively connects an external source to the accumulator and the control valve.

An auxiliary hydraulic system including an accumulator, a control valve, and a hydraulic connector. The accumulator connects to a primary hydraulic system including a hydraulic pump, a brake circuit, and a steering circuit. The control valve selectively allows or prevents flow from an accumulator to at least one of the brake circuit and the steering circuit. The hydraulic connector selectively connects an external source to the accumulator and the control valve.

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 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.