Active Stabilization System: Overview
The Dynamic Response system provides improved vehicle handling and ride characteristics and is active for both on and off-road driving.
The Dynamic Response system uses two accelerometers to detect vehicle cornering forces and inputs from the steering angle sensor to supply data to a dynamic response control module. The control module then operates solenoid valves in a valve block which apply hydraulic pressure to actuators fitted to the front and rear stabilizer bars. The application of hydraulic pressure to the actuators applies a specified amount of torque to the stabilizer bars to counteract the cornering forces and minimize vehicle body roll.
The following illustrations demonstrate the difference in body angle between a conventional 'passive' (non-Dynamic Response) stabilizer bar vehicle and a vehicle fitted with the Dynamic Response system.
| Item Number | Description |
|---|---|
| A | Direction of travel - Right hand bend |
| B | Body roll |
| C | Drive line roll |
| D | Tire squash |
| E | Dampers |
| F | Body roll angle |
| G | Drive line roll angle |
| H | Direction of stabilizer bar twist |
| Item Number | Description |
|---|---|
| A | Direction of travel - Right hand bend |
| B | Body roll |
| C | Drive line roll |
| D | Tire squash |
| E | Stabilizer bar |
| F | Direction of stabilizer bar twist |
| G | Dampers |
| H | Drive line roll angle |
| I | Reduced body roll with Dynamic Response system |
The Dynamic Response system is electrically and hydraulically operated. Electrical and hydraulic operation is controlled by the Dynamic Response control module which is located on the driver's side 'A' pillar, behind the instrument panel.
The Dynamic Response system comprises front and rear stabilizer bars with integral actuators, two accelerometers, a control module, a hydraulic pump, a valve block and a fluid reservoir.
The Dynamic Response system prevents body roll with cornering forces of up to 0.4 g. From 0.4 g there is a progressive increase in body roll but significantly lower than on a 'passive' system. A 'passive' system will have a progressive increase in body roll angle as soon as cornering forces are applied and will have a greater roll angle than the Dynamic Response system for the same cornering force.
The Dynamic Response system can also detect when the vehicle is driven off-road. If off-road conditions are detected and the vehicle is traveling at 25 mph (40 km/h) or less, the control module will reduce roll compensation. On side slopes of more than 11 degrees the Dynamic Response system will switch to a 'locked bars' condition at slow speed.
Lateral acceleration of the body is sensed by two accelerometers and signals from these are transmitted to the control module. The engine driven hydraulic pump supplies a constant hydraulic flow to the valve block. Two directional control valves are solenoid operated by the control module and supply hydraulic pressure to the applicable side of each actuator to apply a force equal to and opposite to the force applied to the stabilizer bar. In operation the Dynamic Response system maintains the attitude of the vehicle body when cornering.
The Dynamic Response hydraulic system uses a semi-synthetic hydraulic fluid which is the same fluid used in the power steering system. The total capacity of the Dynamic Response system is 2.50 liters (0.66 US gallons).
- Dynamic Response components are thoroughly cleaned externally before work commences
- All opened pipe and component ports are capped immediately
- All fluid is stored in clean containers.
In the event of a control module or hydraulic failure the system will 'fail-safe' to a 'locked bars' condition. The 'locked bars' condition will allow the stabilizer bars to operate in a similar manner as conventional 'passive' stabilizer bars. Prolonged cornering forces will allow a progressive increase in roll angle due to hydraulic leakage through the actuators and valve block. Failures of the system are relayed to the driver by illumination of the air suspension/dynamic response warning indicator in the instrument cluster, an audible warning chime and a message displayed in the instrument cluster message center. Faults are recorded by the control module and can be retrieved using a Land Rover approved diagnostic system.
When the ignition switch is moved to position II, the warning indicator is illuminated for two seconds to check functionality. The warning indicator functionality can also be checked using a Land Rover approved diagnostic system.
A Land Rover approved diagnostic system must also be used to perform a bleeding procedure after repair or maintenance operations have been performed. This is to ensure that the system is completely free from air. Trapped air in the system can significantly reduce system performance.