Part 1

Active Stabilization System

Dynamic Response Component Location

NOTE:
LHD (left-hand drive) V8 Petrol shown, other models similar









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 lateral acceleration and inputs from the steering angle sensor and vehicle speed to supply data to the 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 reduces 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.

Conventional 'Passive' Stabilizer Bar









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, hydraulic pipes, hydraulic hoses, a valve block and a fluid reservoir.
The Dynamic Response system reduces 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, signals from these together with steering angle and vehicle speed 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 body roll force. 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).

CAUTION: The Dynamic Response hydraulic system is extremely sensitive to the ingress of dirt and debris. The smallest amount can cause the system to become unserviceable. It is imperative that the following precautions are followed:
- 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 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 hydraulic system response test after bleeding post 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.

FLUID RESERVOIR
The fluid reservoir is located in the front right hand side of the engine compartment. The reservoir is attached to the front of air cleaner housing or radiator cooling pack by two slotted rails which positively locate the reservoir.
The reservoir is a molded plastic container with a twist lock neck which is fitted with a sealed cap. Two connections on the bottom of the reservoir provide for connection of the feed pipe to the pump and the return pipe from the valve block.
A non-serviceable filter assembly is fitted to the base of the reservoir. The filter is made from a fine nylon mesh which is molded into the bottom of the reservoir. The filter removes particulate matter from the fluid before it is drawn into the pump.
Upper and lower fluid level marks are molded onto the reservoir body. The capacity of the reservoir to the upper level mark is 0.4 liter (0.11 US gallon).

DYNAMIC RESPONSE PUMP
The Dynamic Response hydraulic pump is located on the RH (right-hand) side of the engine. The pump is attached to a mounting bracket below the generator on TdV6 engines and above the generator on V8 petrol engines. On both engines the pump is driven by the accessory drive belt from the crankshaft.









The hydraulic pump is driven at approximately 1.7 times crankshaft speed by the auxiliary drive belt. The pump is a radial piston type which delivers fluid at high pressures.
The radial pump has eight pistons located in bores in a cylinder housing. A balanced central shaft, which is driven by a pulley and the auxiliary drive belt, has a cam which operates the pistons as the shaft rotates.
As the cam lobe reaches each piston, the piston is pushed outward, moving the fluid above the piston. The pressure created by the fluid flow from the bore opens a spring loaded discharge valve. When the valve opens, the now pressurized fluid flows, via the silencer volume area of the cylinder housing, to the outlet port. The silencer volume assists with damping out operating noise from the pump. When the piston reaches its full stroke, the flow reduces and the discharge valve closes under spring pressure.
As the cam lobe moves away from the piston, a spring pushes the piston down the bore, creating a vacuum above the piston. As the piston moves down the bore, ports in the piston are exposed and connect with the fluid inlet port. The vacuum draws fluid into the piston filling the piston and the chamber above it. As the piston is again pushed upwards, the ports in the piston are closed off by the bore and the pressurized fluid opens the discharge valve and flows to the outlet port.
The above sequence is applied to each of the eight pistons for every revolution of the shaft and cam. When the engine is running the sequence occurs rapidly creating a constant flow of fluid. The fluid flow varies with engine speed and the rotational speed of the shaft. The pressure applied to the actuators, created by the flow from the pump, is controlled by the pressure control valve in the valve block.
The pump has a displacement of 6cm3/rev and an operational pressure of 165 bar (2248 lbf/in2). The pump output flow ranges from 6.5 l/min (1.7 US Gallons/min) at idle to 10 l/min (2.64 US Gallons/min) at 1000 rev/min and above.

DYNAMIC RESPONSE VALVE BLOCK
The valve block is located below the RH (right-hand) sill of the body and is secured with three bolts and rubber bushes to captive nuts located in the chassis. The rubber bushes isolate the valve block preventing hydraulic noise from transmitting through the body.









The valve block directs hydraulic pressure to the actuators via solenoid operated directional control valves. A solenoid operated pressure control valve regulates the required pressure to the actuators. The three solenoid valves are controlled by signals received from the dynamic response control module. A pressure transducer monitors the pressure generated by the Pressure Control Valve (PCV). A serviceable high pressure filter is installed into the underside of the valve block and filters the hydraulic fluid before it reaches the control valves. The filter must be changed at the intervals defined on the vehicle service schedule.
The two Directional Control Valves (DCV's) are fitted to ports in the top face of the valve block. The DCV's are screwed into the valve block and are sealed with O rings. Each DCV has a solenoid for electrical operation of the valve. The solenoid is sealed to the DCV with two O rings and secured with a threaded nut. The nut, coil and O rings are serviceable parts. The DCV's are non-serviceable and failure of a DCV requires replacement of the valve block assembly.
The PCV is fitted to a port in the rear facing end of the valve block. The PCV is screwed into the valve block and is sealed with O rings. The PCV has a coil for electrical operation which is sealed to the PCV with two O rings and secured with a threaded nut. The nut, coil and O rings are serviceable items. The PCV is serviceable.
The pressure transducer is located in the forward facing end of the valve block and is sealed with an O ring. The pressure transducer measures the hydraulic pressure and returns a signal to the Dynamic Response control module.
A high pressure filter locates in a port on the lower face of the valve block. The gauze and fiber filter is sealed in the port with O rings and is secured with a threaded cap which is also sealed with an O ring. A threaded hole in the lower face of the filter allows a bolt to be fitted to remove the filter from the port. If a system hydraulic component is replaced, the filter must also be replaced.
Four ports are located on the forward facing end of the valve block and two ports on the opposite end. Each port is fitted with a seal pack which contains two O rings and backing rings. The pipes locate and seal in the seal packs and are secured to the valve block with studs and nuts.

ACTUATORS AND STABILIZER BARS
Two stabilizer bars with integral hydraulic actuators are used for the Dynamic Response system. The actuators apply a hydraulically generated force or rotational torque to the stabilizer bar to oppose lateral forces caused by the vehicle cornering.

Actuator Sectional View









Each actuator has a piston which is attached to the inner part of a rota linear ball screw, which is splined to one half of the stabilizer bar. The outer part of the ball screw is crimped and welded into a housing which is attached to the other half of the stabilizer bar. As pressure is applied to one side of the piston or the other, the ball screw converts the linear force applied to the piston into a rotational torque between the two halves of the stabilizer bar.

Front Actuator and Stabilizer Bar









Rear Actuator and Stabilizer Bar

NOTE:
The internal piston size of the rear actuator changes amongst the different vehicle derivatives, it is important to ensure the correct parts are fitted to the relevant derivatives.









NOTE:
On vehicles from 2007MY, the positions of the FRONT actuator ports have been moved and therefore care must be taken to ensure matching pipes and actuators are fitted in service.
Two hydraulic connections provide for the attachment of the hydraulic pipes from the valve block. The connections provide hydraulic flow to each side of the actuator piston.
The front and rear actuator assemblies are similar in their construction, with the rear actuator being smaller than the front. Each stabilizer bar is made from 34 mm (1.34 in) diameter spring steel bar.
The actuator assembly and the stabilizer bars are not serviceable items. Only the stabilizer bar attachment bushes, brackets and stabilizer links are serviceable components.
The front stabilizer links are not handed on the front stabilizer bar and are also common to vehicles not fitted with Dynamic Response. The rear stabilizer links are unique to vehicles with Dynamic Response. The Dynamic Response rear links are identified by a grey color plastic bearing moulding. The passive (non-Dynamic Response) links can be identified by a white colored plastic bearing moulding.
The front stabilizer bar and actuator is attached to a chassis strengthening member known as the secondary load path and to the front cross-member. Two serviceable, split rubber bushes are fitted to the stabilizer bar and are located in cast brackets. Each bracket is secured to the secondary load path with two bolts and to the front cross-member with a third bolt.
The rear stabilizer bar and actuator is attached to fabricated brackets which are located on the outside of the chassis side members, forward of the rear wheels.
Two rubber bushes are fitted to each stabilizer bar and are located in clamp brackets. The front and rear bushes and brackets are not interchangeable.
On both the front and rear stabilizer bars, roll correction force is transmitted to the suspension arm via ball jointed stabilizer bar links. The front links are attached to the front suspension upper arm and the rear links are attached to the rear lower arm.
Each front stabilizer link is fitted with a hardened steel washer which is located between the stabilizer bar and the link ball joint and the upper arm and the link ball joint. It is important that these washers are in the correct position and the correct, hardened washers are fitted. Failure to fit the washers or using incorrect washers will result in relaxation of the torque on the self-locking nut and damage will be caused to the stabilizer bar, link and suspension upper arm.