ACTIVE CURVE SYSTEM controls body roll through active anti-roll bars at the front and rear axles. In the 166 family, it works alongside air suspension and adaptive damping, with each system acting on a different part of the chassis. Mercedes-Benz Hong Kong described it as an optional M-Class system in April 2012. Sources
Hydraulic pressure supplies the corrective torque
The original X166 GL technical introduction describes two active anti-roll bars replacing the passive bars, with two hydraulic rotary actuators. The control unit regulates hydraulic pressure in the actuators using stored control maps; lateral acceleration is a principal input. The actuators let the bars apply controlled torque to oppose body roll as the vehicle corners. Sources
A pump and oil reservoir supply the hydraulic circuit. Daimler’s service bulletin for model 166 with AIRMATIC code 489 and ACS code 468 describes front- and rear-axle oil pressures. Hydraulic roll control thus operates alongside the pneumatic spring system. Sources
Three systems, three jobs
The original M-Class manual describes ACS response changing with the selected ADS mode: Comfort reduces body roll, while Sport suppresses it more strongly. The underlying jobs remain separate. Sources
| System | Main function |
|---|---|
| AIRMATIC | Air springs support the vehicle and provide levelling and ride-height functions. |
| ADS | Adaptive dampers change the resistance to suspension movement. |
| ACTIVE CURVE SYSTEM | Active front and rear anti-roll bars control the body’s roll response. |
A firmer damping setting and greater active roll resistance can be selected together: one changes damper force while the other acts through the anti-roll bars. Sources
Hong Kong applications
For the W166 M-Class, the April 2012 local manufacturer release presented ACS as an option that could be combined with AIRMATIC/ADS and the ON&OFFROAD package. The April 2014 Hong Kong GL 63 AMG release described AMG RIDE CONTROL with ACS. The local GLS manufacturer release later listed ACTIVE CURVE separately as an additional option. Sources
Low-range gearing and differential locking belong to the separate ON&OFFROAD package; they do not come from the active anti-roll system.
Sources
- Mercedes-Benz Hong Kong, A generation ahead: the new Mercedes-Benz M-Class, 13 April 2012, manufacturer-authored release preserved by 1888PressRelease; optional ACS, front/rear active bars and AIRMATIC/ADS relationship.
- Daimler AG, Einführung neue GL-Klasse, Typenreihe X166, June 2012, order 6516 1394 00, printed p. 56 / viewer p. 57: two hydraulic rotary actuators, pressure control and lateral acceleration input. Original manufacturer technical publication preserved by ManualsLib; X166 construction scope.
- Daimler AG, service bulletin LI32.34-P-058736, version 3, 25 April 2019, PDF pp. 1–2, NHTSA-hosted original: model 166 with codes 489/468, front/rear axle oil pressures, pump, reservoir and hydraulic fluid. Service evidence is used to identify hardware, not to infer failure frequency.
- Mercedes-Benz, M-Class Operator’s Manual, 1665848681, Edition B 2013, as at 10 May 2012, printed pp. 209–210 / PDF pp. 211–212: ADS Comfort/Sport and ACTIVE CURVE SYSTEM response. North American manual including optional and country-dependent equipment.
- Mercedes-Benz Hong Kong, The New Mercedes-Benz GL 63 AMG: Perfect Blend Of Style And Performance, 10 April 2014, AMG RIDE CONTROL with ACTIVE CURVE SYSTEM in the locally priced GL 63 AMG offering.
- Mercedes-Benz Hong Kong / Zung Fu, 全新平治GLS糅合平治GL與S系列–極致路面與越野表現, manufacturer release preserved by 28car; separate additional ACTIVE CURVE option. No reliable publication date shown.