2006
The third generation of Haldex coupling made its appearance on the newly re-designed Land Rover Freelander 2 (LR2 in the United States). With enhanced capabilities, it allows more immediate off road response. The Freelander's 4x4 system has been developed in conjunction with Haldex, whose centre-coupling technology continuously alters the front-rear torque split, normally through a hydraulically operated multi-plate wet clutch. However, Land Rover wanted an electronically controlled centre coupling – linking the propshaft to the rear differential – that could pre-engage at rest to reduce wheelspin from standing starts, engage quickly when traction loss was detected and disengage quickly without compromising stability control systems. The system also had to transmit the necessary torque to achieve Freelander 2's off-road traction demands. The result is used exclusively on Freelander 2, and pre-emptively engages four-wheel drive quickly and completely. An improved high-pressure pre-charge pump charges the hydraulic system as soon as the engine is started, allowing for full-time 4x4 from rest. It also reduces the time taken to achieve full torque once wheel-slip has been detected – within 15 degrees of wheel-slip rotation (compared with 50 degrees of wheel-slip rotation with the previous generation Haldex). The Freelander 2's Haldex unit is designed to allow up to 1500 Nm of torque transmission. An accumulator also speeds up the unit's response. Full torque transmission can be achieved in 150 milliseconds. In effect, the new Haldex coupling gives the benefits of full-time 4x4 and the efficiency and fuel economy of an on-demand system.
This generation of Haldex coupling is later shared with Volvo's complete lineup (Manufactured 2005-2008, depending on model) and is called "Instant Traction" in documentation by Volvo.
Read more about this topic: Haldex Traction, Third Generation