2002 Maybach 62

Everything under control

Safety, comfort, handling – three aspects that were writ large during the design and development of the suspension system for the Maybach. To achieve these aims the luxury brand uses trailblazing innovations introduced by its sister-brand Mercedes-Benz, thereby also setting standards in the high-end luxury motor car segment where suspension technology is concerned:

• Safety: In addition to large brake discs at both front and rear the new Maybach is equipped with the electrohydraulic braking system Sensotronic Brake Control (SBC™). The engineers in Sindelfingen have developed this technology further for the Maybach and configured it to meet the need for enhanced braking performance. Together with ESP®, ASR, ABS and Brake Assist the Maybach therefore features the most advanced and efficient dynamic control systems.

• Comfort: The electronically controlled air suspension system AIRMATIC DC (Dual Control) enables the luxury car to achieve a new dimension in ride comfort.

• Handling: The Maybach proves that a large, high-prestige motor car can also be outstandingly agile and dynamic. This is in large measure due to AIRMATIC DC with its automatic, situation-related adaptation of spring and shock absorber stiffness and the sophisticated design of the axles.

AIRMATIC DC: a combination of air suspension and adaptive damping

The suffix "DC" stands for "Dual Control" and refers to the dual function of AIRMATIC: the system combines an actively controllable air suspension with the Adaptive Damping System (ADS II), thereby influencing both springing and damping in equal measure. ADS II regulates the shock absorber force depending on the road surface, driving style and vehicle load, while rubber bellows filled with compressed air at the axles ensure comfortable springing. The system in the Maybach operates at a pressure of six to ten bar.

AIRMATIC DC controls the air volume in the rubber spring bellows depending on the driving situation. On rapid bends or under similarly high dynamic loads, for example, the air suspension briefly deactivates part of the air volume it contains and thereby stiffens the spring action to reduce body roll and pitching. During normal driving the entire air volume remains active, providing soft springing and maximum comfort.

This adaptive activation and deactivation of the ’comfort’ air volume and the automatic adjustment of shock absorber stiffness are the result of a practically instantaneous calculation process (algorithm) during which the micro-processor compares current sensor data for the steering angle, linear and lateral acceleration and vehicle attitude with specified values stored in a memory.

The Adaptive Damping System (ADS II) supports these control processes with what is known as a skyhook algorithm. This allows the damping forces at each wheel to be regulated within less than 0.05 seconds so that the forces acting on the vehicle body from the wheel movements are noticeably reduced. During a braking manoeuvre, for example, the system increases suspension compression at the front axle and rebound at the rear axle, reducing the tendency of the body to dive.

To make this lightning-fast intervention possible, the shock absorbers of the Maybach are equipped with electrically operated solenoid valves which separately influence the compression and rebound of each wheel according to the situation and its requirements.

In addition the driver is able to adjust the spring rate and damping himself at the touch of a button. There is a choice between a comfort-focused basic setting (switch position 0) and two positions with tauter spring and damper settings. To reduce drag and improve handling stability the level of the body is automatically lowered by 15 millimetres when the speed reaches 140 km/h. Below 70 km/h the body is raised to its normal level again.

In addition to the air springs with their newly-developed, particularly thin-walled and harshness-optimised rubber bellows, the ADS II shock absorbers and the control unit, AIRMATIC DC includes various components which are mainly responsible for a rapid build-up of pressure and reliable pressure storage:

• The pressure supply unit consists of an electrically powered compressor with a regenerative drier and a valve unit.

• The distribution block features the pressure reservoir charge valve, a central pressure sensor and the connectors for the pneumatic lines.

• The two reservoirs maintain a charge pressure of up to 16 bar which the system uses when at rest or at low speed to ensure a rapid and noiseless self-levelling effect.

• Two sensors on the front axle and one on the rear axle monitor the level of the vehicle body. In addition the AIRMATIC control unit receives signals from three acceleration sensors on the bodywork and a steering angle sensor.

Front suspension: double wishbones and an efficiently isolated subframe

In view of the outstanding performance and weight of the Maybach the choice by the development engineers naturally fell on a double wishbone front suspension. This design meets all the requirements for this unique luxury motor car while providing a low level of road roar and tyre vibration. It consists of forged steel and aluminium components, the lower wishbone being of forged steel and the upper of aluminium.

Wheel location is via two control arms on each side: the upper wishbone is directly connected to the body via large rubber mountings, while the lower wishbone supporting the air suspension spring strut is attached to a large sheet steel subframe, also via rubber mountings, which is in turn isolated from the body by four hydraulically dampened bearings. This technology makes a major contribution to the high vibration comfort of the Maybach.

Steering: a system with many comfort benefits

In the case of the steering the engineers likewise opted for the system that offers the most comfort benefits with the front axle load and steering forces of the Maybach, namely recirculating-ball steering.

This operates with speed-sensitive power assistance and has an electronically controlled regulating valve to reduce the steering effort from approx. five Newton metres on fast roads to only approx 2.5 Newton metres when parking or manoeuvring at low speeds. The design features an inner and outer jacket tube which can be moved relative to each other via a spindle, enabling the steering wheel to be individually adjusted for reach from the normal position by up to 21 millimetres to the front and up to 35 millimetres to the rear. The driver need only operate a lever adjacent to the steering column and an electric motor carries out his wishes. The same applies to the height adjustment by up to 36 millimetres upwards and a maximum of 14 millimetres downwards. This adjustment is carried out by a further electric motor, a gear and two lifting spindles - a high level of technical sophistication for maximum individual comfort.

The rim of the steering wheel (diameter 384 millimetres) is covered in fine leather and wood and is of die-cast aluminium.

SBC: electrohydraulic braking system with eight circuits

The introduction of Sensotronic Brake Control (SBC) by Mercedes-Benz in 2001 began the company’s entry into the world of so-called "by wire" systems, which no longer transmit the driver’s commands mechanically or hydraulically, but electronically by cable. Maybach has benefited from the technological lead of its sister-brand and equips its high-end luxury motor car with a further development of the SBC system.

By contrast with the Mercedes-Benz SL and E-Class, which are likewise equipped with SBC, the system in the Maybach has two central control units, two high-pressure reservoirs, two hydraulic units and therefore a total of eight brake circuits. In this way the engineers have done justice to the higher hydraulic volume requirement of the larger braking system in the Maybach.

The two powerful microprocessors interact constantly and control all braking processes. When the driver depresses the brake pedal, sensors register the pressure and speed of pedal operation and transfer this information to the control units to initiate an almost instantaneous and highly dynamic brake management process. At the same time the SBC microprocessors are also receiving sensor signals relating to the current driving situation from other electronic assistance systems, and are therefore able to adapt the braking command precisely to the actual conditions for optimal deceleration and handling stability. During the process SBC individually calculates the brake force for each wheel.

The brake fluid in the two high-pressure reservoirs is under a constant, high pressure of 140 to 160 bar, which guarantees the extremely short response times of this innovative braking system. The microprocessors regulate this pressure to suit the requirements, and also control the electric pump connected to the reservoir. The eight pressure modulators in the hydraulic units transfer the braking pressure to the wheels, with two responsible for each wheel. In this way the commands from the electronic control units can be precisely implemented at each wheel.

The extremely dynamic build-up of pressure and precise monitoring of driver and vehicle behaviour by means of a sophisticated sensor system are the greatest advantages of this unique braking system and significantly improve handling safety. During emergency braking, for example: SBC even recognises a rapid movement of the driver’s foot from the accelerator to the brake pedal as an indication of an emergency situation and responds automatically. With the help of the high-pressure reservoir the system increases the pressure in the brake lines and immediately brings the brake linings into light contact with the brake discs, ensuring that they are able to exert their full pressure at once when the brake pedal is operated.

SBC also improves handling safety in other respects, as the system works together with other control systems in the Maybach via a databus:

When skidding is imminent SBC supports the Electronic Stability Program ESP and ensures extremely rapid, finely metered braking impulses which reliably and comfortably stabilise the vehicle.

When braking on bends the variable brake force distribution actively influences the oversteer and understeer characteristics of the car: SBC enables the brake pressure to be metered in such a way that it is automatically increased at the outer wheels, transferring greater brake forces as a result of larger tyre contact forces. At the same time the brake forces at the inner wheels are reduced in favour of the lateral stabilising forces which are important for directional stability. The result is more stable braking behaviour with optimal deceleration values.

In wet conditions Sensotronic Brake Control removes the film of water from the brake discs by briefly applying the brake linings at regular intervals, thereby ensuring that the system can operate with full efficiency at all times. This automatic brake-drying function is activated when the windscreen wipers have been in operation for a certain time. The finely metered braking impulses are not noticeable to the driver.

Mechanically isolating the SBC brake pedal from the remaining braking system together with proportional pressure control improves comfort when braking – especially during heavy deceleration or when the anti-lock braking system is activated. The pulsing usually felt in the brake pedal during ABS intervention no longer occurs.

The Soft-Stop function is another comfort-enhancing feature of the braking system. This enables the vehicle to be brought to a particularly gentle stop, e.g. in city traffic with frequent traffic lights. This is made possible by finely metered pressure control, as SBC reduces the brake servo pressure shortly before the vehicle comes to a halt and thereby prevents the characteristic jerk frequently felt when braking to a stop. The Soft-Stop function is always active – the system only gives priority to rapid deceleration during emergency braking or during slow manoeuvres.

Braking system: ready for any challenge with six brake callipers

An exceptionally powerful and imposing luxury motor car requires an equally exceptional braking system. SBC is a highlight which makes the new Maybach saloons something special in this area, and this system is complemented with large, internally ventilated front disc brakes, each of which features two brake callipers. This means that a remarkable 248 square centimetres of brake lining surface are available to decelerate this high-end luxury car safely and reliably.

Rear suspension: redesigned multi-link independent suspension

The well-proven multi-link independent rear suspension used in Mercedes models also ensure precise wheel location and a high level of rear suspension comfort in the Maybach. Almost all the components of this sophisticated five-link system have however been newly developed for the Maybach.

The radius rods and camber arms as well as the track rods are of forged steel, while the spring links are of sheet steel. The axle carriers are two tubular steel sections connected by two cross-members (sheet steel) and isolated from the vehicle body by hydraulically dampened bearings. The control arms have their mounting points on the sides of the axle carriers and likewise feature large rubber bearings.

Wheels and tyres: a majestic 19 inches

19-inch tyres accentuate the imposing appearance of the Maybach luxury automobile, which is equipped with attractive, cast light-alloy wheels as standard. The wheel size is 8 J x 19 ET 67, while tyres are of size 275/50 R 19. On request the wheels can be fitted with a run-flat feature in the form of a steel supporting ring which allows a defective tyre to continue running. The innovative tyre sealing kit TIREFIT is standard equipment in the Maybach – a fully-fledged spare wheel is available at no extra cost as an alternative.

An electronic control system which constantly monitors the tyre pressures is also provided as standard. This function is performed by sensors in the four tyre valves which measure both the inflation pressure and inside temperature of each tyre. These data are usually transmitted to special antennae in the wheel arches by radio once every minute, then transferred to a microprocessor by cable. This evaluates the signals from the four transmitters according to their different identification codes and is therefore able to provide the driver with specific information concerning the air pressure in each tyre. The values appear in the central display in the instrument cluster. In the event of a sudden and rapid pressure loss in any of the tyres an appropriate signal is immediately sent to alert the driver in good time.