On road or off, Range Rover suspension up to the task (video)

  • 25-Jul-2013 03:47 EDT
Still from vid of Patrick George.jpg

Terrain Response 2 system in the supercharged Range Rover analyzes road-surface and driving conditions to automatically switch between the most appropriate programs: General, Grass/Gravel/Snow, Mud/Ruts, Sand, and Rock Crawl. (Patrick Ponticel)

Loaded with new features and capabilities, and built on an all-new lightweight aluminum platform, the 2013 Range Rover from Jaguar Land Rover has a million stories to tell. One of the more interesting ones comes out of its suspension (watch video).

The suspension itself did most of the talking earlier this year on a media ride-and-drive for the SUV, acquitting itself as nobly on the stony and hilly terrain outside Kanab, UT, as on the smooth roadways paralleling the Utah-Arizona border north of the Grand Canyon. The SUV’s impressive duality comes at a high sticker price ($83,500 to $130,950), of course, but Land Rover seems sure its big bet on the fourth-generation Range Rover will pay off.

Also having a lot to say about the suspension was Jaguar Land Rover’s Chief Chassis Engineer, Mike Gallery, who flew in from the company’s engineering headquarters in England to serve as a resource during the ride-and-drive. His unit came up with a completely new fully independent suspension architecture with virtually no parts carryover from the previous system. A wide-spaced double-wishbone design is used in the front; an advanced multilink system is in the rear.

Many suspension components are of aluminum (as is the vehicle body) or lightweight steel. The subframes also are aluminum, “which is quite novel in the SUV world,” Gallery said. Suspension and subframe weight savings total 30 kg (66 lb).

Land Rover’s fifth-generation air spring system, called 4CAS (four-corner air suspension), is employed. It features “some optimizations in terms of weight reduction…and more refinement in controlling pressure and all the parameters around that,” said Gallery. For the first time on Range Rover, the air suspension is combined with the company’s Adaptive Dynamics system, “which for us is essentially continually variable dampers.” Sensor inputs are read more than 500 times/s. The system is offered on all model variants.

Also offered for the first time on Range Rover is the company’s two-channel (front and rear axles) active lean-control system called Dynamic Response (DR). Fitted as standard to the supercharged V8 model, DR essentially uses active antiroll bars to change roll stiffness balance and roll angle. In terms of on-road dynamics, the system delivers “flatter, more confident cornering with a natural, intuitive steering feel,” said Gallery, and reduces head toss. If the system detects off-road driving conditions, the control module isolates the stabilizer bar and reduces the level of roll compensation, allowing for “significantly more cross-axis wheel articulation (wheel travel) than you would normally get,” he added, increasing the contact patch with the terrain.

Ground clearance is improved, and the Range Rover offers what Gallery described as “a fairly spectacular wading depth of 900 mm.” Enabling the much greater wading depth is a completely redesigned engine breathing system featuring “Queen Mary” air intakes between the front fender and the hood. The system features “an intricate labyrinth of pipes and traps and filters for air to get into the engine.”

With the new air suspension system, the new Range Rover can be lowered 2 in (50 mm) to ease entry into the SUV. For off-roading, an automatic system varies between two ride heights: intermediate at 1.6 in (40 mm) up to 50 mph (80 km/h) and full off-road at 2.95 in (75 mm). That compares with the outgoing model, which offered only one off-road ride height: 2.2 in (55 mm). In addition, if vehicle sensors (e.g., ride height, wheel speed, suspension pressure) indicate the SUV is beached, it will be raised another 1.4 in (35 mm). Height can be manually extended 1.4 in (35 mm) beyond even that.

The automatic next-generation Terrain Response 2 system in the supercharged Range Rover analyzes road-surface and driving conditions to automatically switch between the most appropriate programs: General, Grass/Gravel/Snow, Mud/Ruts, Sand, and Rock Crawl. To say the Range Rover’s performance in Rock Crawl mode during the media ride-and-drive was impressive might be an understatement: the SUV extricated itself from implausibly deep sand in one moment and conquered implausibly steep and uneven rock formations in the next. The feature makes adjustments to the chassis, engine, transmission, and center differential to account for the terrain under wheel. It provides the driver with recommendations, such as advising when to select low range or off-road ride suspension height when the system calculates that it is necessary. The system can be switched into manual mode.

Complementing Terrain Response 2 is a suite of all-terrain technologies, including Hill Descent Control, Gradient Release Control, Hill Start Assist, Dynamic Stability Control, Electronic Traction Control, and Roll Stability Control. The operation of these braking and stability systems is enhanced by the latest Bosch six-piston brake modulator, which delivers faster responses and smoother, quieter, and more precise operation than in the outgoing model. It is also an enabler for the Q Assist system that will bring the SUV to a complete stop and return it to the preceding active cruise control spacing at the touch of the throttle.

Other aspects of the vehicle were highlighted in a previous article by AEI at http://www.sae.org/mags/aei/11341.

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