Discussions of suspension systems inevitably follow their designs, centering upon the trade-offs and compromises between ride and handling. In the case of high center-of-gravity SUVs, in particular, the trade-offs can be even more dramatic, given the conflict between the demands of driving a tall vehicle on the road and equipping it to handle the rough terrain of off-road driving.
All suspensions deal with two basic dynamic modes, vertical articulation (bounce and rebound), and roll (departure from a flat horizontal attitude when cornering hard or negotiating uneven terrain). Historically, whether in passenger cars or SUVs, there were necessary trade-offs and compromises between these two basic modes in any suspension, because it had to deal with both and could be optimized for neither. One solution was active systems, in which electronically controlled motors introduced active countermeasures, but such systems are complex, heavy, and expensive.
Tenneco’s Kinetic Dynamic Suspension System is the kind of breathtakingly simple solution that makes it a model of innovation: it decouples the two modes by the use of hydraulic circuitry and valving – thus allowing both the ride-enhancing benefits of compliant articulation, and increased roll stiffness, either-or choices until then. The system is totally passive, reacting in real time to whatever it encounters. The brilliant innovative insight was to decouple the two modes, and do it in a way that does more with less, a hallmark of innovation.
This suspension innovation insight means greater and softer suspension travel, plus stiffer anti-roll, and paradoxically, both better handling and compliance both on-road and off-road. Head toss and fatigue are greatly reduced in both situations.
The initial commercial appearance of KDSS was as an option on the 2004 Lexus GX 470, and it will be standard equipment on the 2005 model. This suspension system is usable with or without suspension dampers, including adjustable or self-adjusting ones, and with or without stabilizer bars, including much larger ones than otherwise possible.