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 control system is disclosed for use in load-carrying vehicles. The system controls a response of a suspension cylinder configured to support a main body of a vehicle in relation to a ground-contacting portion of the vehicle. A main accumulator is configured to contain a main compressible gas volume and is fluidly connected with the suspension cylinder. An auxiliary accumulator is configured to contain an auxiliary compressible gas volume. A valve is configured to selectively fluidly connect the auxiliary accumulator to the suspension cylinder. When the valve is open, compressing the suspension cylinder compresses both the main compressible gas volume and the auxiliary compressible gas volume. When the valve is closed, the auxiliary accumulator is fluidly isolated from the suspension cylinder. A processor is configured to automatically open or close the valve using a solenoid actuator based on one or more operating parameters of the vehicle.

A vehicle suspension control system is disclosed for use in load-carrying vehicles. The system controls a response of a suspension cylinder configured to support a main body of a vehicle in relation to a ground-contacting portion of the vehicle. A main accumulator is configured to contain a main compressible gas volume and is fluidly connected with the suspension cylinder. An auxiliary accumulator is configured to contain an auxiliary compressible gas volume. A valve is configured to selectively fluidly connect the auxiliary accumulator to the suspension cylinder. When the valve is open, compressing the suspension cylinder compresses both the main compressible gas volume and the auxiliary compressible gas volume. When the valve is closed, the auxiliary accumulator is fluidly isolated from the suspension cylinder. A processor is configured to automatically open or close the valve using a solenoid actuator based on one or more operating parameters of the vehicle.

A method and apparatus for a vehicle shock absorber comprising a main damper cylinder, a first reservoir and a second reservoir. One embodiment includes a first operational mode where both reservoirs are in fluid communication with the cylinder. In a second operational mode, only one reservoir communicates with the cylinder during fluid evacuation from the cylinder. In each mode, rebound from either or both reservoirs may travel through a single, user-adjustable metering device.