A dump truck pitching control system that can improve the ride quality of a vehicle body and the drive stability during traveling is provided. The present invention includes: a pitching state amount detection section 194 that detects a state amount of the pitching movement of the vehicle body 10; a spring characteristics calculation section 197 that calculates spring characteristics of suspension cylinders 30, based on detection results of stroke sensors 306, pressure sensors 307, and temperature sensors 308; a pitching target amount calculation section 192 that calculates a target amount of the pitching movement of the vehicle body 10, according to the spring characteristics calculated by the spring characteristics calculation section 197; and a torque correction value calculation section 193 that calculates a torque correction value required to correct the pitching amount, according to the spring characteristics calculated by the spring characteristics calculation section 197.

Pressure-sensitive valves are incorporated within a dampening system to permit user-adjustable tuning of a shock absorber. In one embodiment, a pressure-sensitive valve includes an isolated gas chamber having a pressure therein that is settable by a user.

A pneumatic suspension system for a vehicle, in which the pneumatic suspension system includes a supply tank, a first set of air springs positioned on a first side of the vehicle; a second set of air springs positioned on a second side of the vehicle, and a dual-action dynamic valve positioned between the first set of air springs and the second set of air springs. The dual-action dynamic valve is connected to the supply tank, the first set of air springs, and the second set of air springs by a series of air hoses. The dual-action dynamic valve is adapted to supply air to either one of the first set of air springs or the second set of air springs while simultaneously exhausting air from the other one of the first set of air springs or the second set of air springs.

Aspects of the disclosure provide a method for communicating motion intention of a vehicle to other road users. The method can include receiving a signal indicating a motion intention of the vehicle, and controlling a suspension system of the vehicle to create a vehicle posture according to the motion intention of the vehicle to show the motion intention of the vehicle to other road users.

A valve control device is configured to execute a specific valve control when a valve switching condition at high pressure is satisfied. The specific valve control switches the spring constant change valves for front wheel to a blocking state and switches a spring constant change valves for rear wheel to a communication permission state. The valve switching condition at high pressure is satisfied when oil pressure of hydraulic oil of rear wheel side oil hydraulic cylinders, which is detected by rear wheel side oil pressure detection means, is more than or equal to a predetermined oil pressure threshold and the traveling state determination means determines that a vehicle is in a predetermined traveling state.

A vehicle suspension damper for providing a variable damping rate. The vehicle suspension damper comprises a first damping mechanism having a variable first threshold pressure, a second damping mechanism having a second threshold pressure, and a compressible chamber in communication with a damping fluid chamber, wherein the second damping mechanism is responsive to a compression of said compressible chamber.

In one aspect, a control system is provided which determines fluid flow in a suspension system for an agricultural machine by determining total fluid in a closed loop piston system. Fluid is determined using position sensors and a pressure transducers and application of the ideal gas with respect to each accumulator. A closed loop control system can then target an amount of fluid for optimum suspension control.

In one aspect, a suspension control system is provided for dynamically adjusting pistons located proximal to wheels of an agricultural machine to account for tire deflection or squat with varying loads. Articulation, pitch, roll and/or machine height can be determined from pressure measurements on the machine to apply such tire height corrections. For sprayers, this allows controlling clearance and suspension height to maintain the boom parallel to the ground to prevent damage.

In one aspect, a suspension control system is provided for dynamically adjusting pistons located proximal to wheels of an agricultural machine to substantially equalize distribution of weight of the machine at each wheel and/or provide a substantially constant desired orientation of the machine above a ground surface thereby protecting laterally extending sprayer booms from contacting the ground. Articulation, pitch, roll and/or machine height can be determined from piston measurements on the machine to apply such height corrections. For sprayers, this allows controlling clearance and suspension height to maintain the boom parallel to the ground to prevent damage.

To improve off-road travel performance, ECU is configured to: set one of front left and right wheels and rear left and right wheels as roll stiffness decrease subject wheels and set another as non-roll stiffness decrease subject wheels; bring a spring switching valve and a leveling valve into an open state for each of the roll stiffness decrease subject wheels, causing left and right hydraulic cylinders to communicate to each other for the roll stiffness decrease subject wheels; and bring the spring switching valve and the leveling valve into a closed state and bring a bypass valve into the open state for one of the left and right wheels of the non-roll stiffness decrease subject wheels, to cause a second gas spring for one of the left and right wheels of the non-roll stiffness decrease subject wheels to communicate to the hydraulic cylinders of the roll stiffness decrease subject wheels.