A hydraulic system for controlling a pair of steerable caster wheels includes a left side actuator and a right side actuator. A rear steering control valve is moveable between a first state for disabling direct control of the left and side actuators and a second state for enabling direct control the left and right side actuators to provide a steer response. A fluid connection continuously connects the pressure source and the fluidic tie rod fluid circuit in fluid communication when the rear steering control valve is disposed in one of the first state and the second state to continuously supply the pressurized fluid to the fluidic tie rod fluid circuit.

A hydraulic system for controlling a pair of steerable caster wheels includes a left side actuator and a right side actuator. A rear steering control valve is moveable between a first state for disabling direct control of the left and side actuators and a second state for enabling direct control the left and right side actuators to provide a steer response. A fluid connection continuously connects the pressure source and the fluidic tie rod fluid circuit in fluid communication when the rear steering control valve is disposed in one of the first state and the second state to continuously supply the pressurized fluid to the fluidic tie rod fluid circuit.

A work vehicle includes a steering wheel, a steering cylinder, a steering valve, a feed line, a return line, an electromagnetic valve, and a controller. The steering valve is configured to supply hydraulic fluid to the steering cylinder in response to steering of the steering wheel. The feed line is configured to feed the hydraulic fluid from the steering valve to the steering cylinder. The return line is configured to return the hydraulic fluid from the steering cylinder to the steering valve. The electromagnetic valve is disposed between the feed line and the return line. The controller opens the electromagnetic valve in response to an oil pressure in the feed line.

A work vehicle includes a steering wheel, a steering cylinder, a steering valve, a feed line, a return line, an electromagnetic valve, and a controller. The steering valve is configured to supply hydraulic fluid to the steering cylinder in response to steering of the steering wheel. The feed line is configured to feed the hydraulic fluid from the steering valve to the steering cylinder. The return line is configured to return the hydraulic fluid from the steering cylinder to the steering valve. The electromagnetic valve is disposed between the feed line and the return line. The controller opens the electromagnetic valve in response to an oil pressure in the feed line.

A hoisting machinery comprises a steering wheel and wheels, wherein the active steering system comprises an active steering device, a hydraulic power steering gear and a hydraulic power steering system, the active steering device is arranged between the steering wheel and a pitman arm of the hoisting machinery, so as to adjust a steering ratio of the steering wheel to the pitman arm according to a driving cycle of the hoisting machinery, and the hydraulic power steering gear is arranged between the steering wheel and the pitman arm, so as to control the hydraulic power steering system to drive steering of the wheels. In the active steering system of the present invention, a hydraulic power steering system is adopted to drive steering of wheels, which can improve capability of overcoming steering resistance and can be applicable to multiple chassis of cranes, thereby enlarging application ranges of the active steering system.

A hoisting machinery comprises a steering wheel and wheels, wherein the active steering system comprises an active steering device, a hydraulic power steering gear and a hydraulic power steering system, the active steering device is arranged between the steering wheel and a pitman arm of the hoisting machinery, so as to adjust a steering ratio of the steering wheel to the pitman arm according to a driving cycle of the hoisting machinery, and the hydraulic power steering gear is arranged between the steering wheel and the pitman arm, so as to control the hydraulic power steering system to drive steering of the wheels. In the active steering system of the present invention, a hydraulic power steering system is adopted to drive steering of wheels, which can improve capability of overcoming steering resistance and can be applicable to multiple chassis of cranes, thereby enlarging application ranges of the active steering system.

A hydraulic steering system, comprising a steering pump and a plurality of digital steering cylinder assemblies Each digital steering cylinder assembly includes a steering cylinder and a digital hydraulic valve configured to selectively communicate a rodless cavity of the steering cylinder with one of the steering pump and a return oil circuit, and communicate a rod cavity of the steering cylinder with the other of the steering pump and the return oil circuit.A controller can be configured to emit a digital pulse signal to a motorand cause the digital hydraulic valve to move towards a first working position or a second working position andA mechanical feedback structure can be configured to be driven by a piston rod of the steering cylinder when the valve core of the digital hydraulic valve moves towards the first working position or the second working position, so as to drive the digital hydraulic valve to return to a neutral position. The system can improve the control precision and the response speed of the steering system.

A hydraulic steering system, comprising a steering pump and a plurality of digital steering cylinder assemblies Each digital steering cylinder assembly includes a steering cylinder and a digital hydraulic valve configured to selectively communicate a rodless cavity of the steering cylinder with one of the steering pump and a return oil circuit, and communicate a rod cavity of the steering cylinder with the other of the steering pump and the return oil circuit.A controller can be configured to emit a digital pulse signal to a motorand cause the digital hydraulic valve to move towards a first working position or a second working position andA mechanical feedback structure can be configured to be driven by a piston rod of the steering cylinder when the valve core of the digital hydraulic valve moves towards the first working position or the second working position, so as to drive the digital hydraulic valve to return to a neutral position. The system can improve the control precision and the response speed of the steering system.

A steering gear component for a vehicle, comprising: a worm, which is mounted so as to be rotatably and axially non-displace able, wherein the worm has a ball screw for receiving a row of balls, and a ball nut, which is drivingly connected to the worm by way of the row of balls, and wherein the ball nut acts as a piston of a cylinder for steering force assistance, wherein a signal transmitter for a sensing element is arranged on the steering spindle and the sensing element is arranged on the worm, or wherein the sensing element is arranged on the steering spindle and the signal transmitter for the sensing element is arranged on the worm.

A steering gear component for a vehicle, comprising: a worm, which is mounted so as to be rotatably and axially non-displace able, wherein the worm has a ball screw for receiving a row of balls, and a ball nut, which is drivingly connected to the worm by way of the row of balls, and wherein the ball nut acts as a piston of a cylinder for steering force assistance, wherein a signal transmitter for a sensing element is arranged on the steering spindle and the sensing element is arranged on the worm, or wherein the sensing element is arranged on the steering spindle and the signal transmitter for the sensing element is arranged on the worm.