Immediately after the market launch of the fully-automated "Mercedes Power-Shift" transmission in the Mercedes-Benz Actros, this 12-speed unit is also being introduced in the Axor. The lightweight transmission is initially available for the model 1843, 1840 and 1836 semitrailer tractors with a 12-litre engine and 428 hp/2100 Nm to 360 hp/1850 Nm. In early next year the three-axle model 2543 to 2536 6x2-chassis will also be optionally available with Mercedes Power-Shift.

The major attributes of this new transmission option include more customer benefits by virtue of further improved economy and faster, more comfortable gearshifts. At the same time the advantages of this transmission, which is light in weight because the basic three-speed gearbox of this range-split transmission is unsynchronised, go hand in hand with the strengths of the Mercedes Axor. Designed with payload-sensitive operations in mind, this vehicle series particu­larly shows these strengths in short-radius and long-distance operations with time and range constraints. It is especially here that the advantages of a fully automated manual transmission, which is able to increase the payload owing to its construction, come to the fore.

In addition to its beneficial effect on vehicle weight, Mercedes Power-Shift with its fully automated operating mode can also help to reduce the overall fuel con­sumption for a journey. Moreover, the new transmission and control tech­nology allows smoother and faster gear changes than even highly experienced drivers are usually able to manage with manual or semi-automated transmissions.

Mercedes Power-Shift also offers the driver numerous practical, additional driving programmes. The further improved availability of vehicles by virtue of the mini­mised risk of operating errors has anyway been a major and inherent characteris­tic of automated manual transmissions since their market launch by Mercedes-Benz more than 20 years ago. All in all, both transport operators and drivers therefore benefit from the new transmission option in the Mercedes-Benz Axor.

Mercedes Power-Shift in the Axor is a package consisting of an unsynchroni­sed, fully automated manual transmission with 12 speeds and highly sophisticated control technology. In addition to the main functions of gear changes and clutch operation, it also includes numerous new operating functions.

Mercedes-Benz has based its new transmission family on the know-how gained from more than 20 years of series production of initially semi-automated and then fully automated manual transmissions. "EPS", the electro-pneumatic gearshift in the SK series in 1985, was followed by the Telligent gearshift as standard equip­ment in the Actros in 1996, coinciding with the optional Telligent auto­mated gearshift.

With Mercedes Power-Shift, is now taking a further step to elevate the automated manual transmission to the industry standard in the commercial vehicle sector. Mercedes Power-Shift reflects a concerted further development of the multi-stage philosophy in Mercedes-Benz powertrain management: 12 precisely suited gears for modern, high-torque engines – specially and therefore eminently suitable for most applications in short-radius and long-distance transport.

Mercedes Power-Shift is based on an internally developed and produced, light-alloy basic transmission with three unsynchronised forward gears and one re­verse gear. A total of 12 forward and four reverse gears are made possible by synchronised range-change and splitter boxes with automatic gearshifts in both the main transmission and upstream and downstream units. The omission of heavy synchromesh packages, which are replaced by a so-called layshaft brake, considerably reduces the moving masses. In conjunction with the latest control technology acting in tandem with extremely sensitive actuators, that makes rapid yet smooth ratio changes possible.

In terms of operation, there is nothing new confronting the Mercedes Power-Shift driver in the Axor – at least not for truckers who have already enjoyed the bene­fits of Telligent automated gear shifting in the Actros. Operation is also extremely easy for newcomers to trucks with a fully automated manual trans­mission, how­ever – after all, that is a basic requirement for a vehicle with an automated transmission.

The two-pedal principle in the footwell is already familiar from the Telligent automated gearshift, and there is no clutch pedal to the left of the steering column. The clutch is operated automatically, therefore foot operation as with a manual transmission is no longer necessary. Now the Axor driver also has the benefit of a joystick-like actuator identical to the Mercedes Power-Shift unit of the Actros. It is situated to his right, mounted on a fold-away extension arm for easy cross-cab access. If the driver wishes, he can change gears here with a flick of the wrist.

Touch-shifting with small or larger ratio changes is possible via a shift paddle or the larger range selector switch. Purely manual operation is possible at any time by pressing a push-button switch. The operating mode freely selected by the driver is shown in the display between the speedometer and the rev counter. Mode " A " for Automatic is the default setting whenever the engine is started.

A logical, easily understood change of principle accompanies the introduction of Mercedes Power-Shift where the display of the selected gear is concerned. Instead of the traditional, separate display of whole and half ratios, there is now an alpha­numerical display from the lowest to the highest gear.

By virtue of this free choice between fully automated, semi-automated and manual gear shifting, Mercedes Power-Shift offers a number of other features which assist the driver in various day-to-day situations. The following additional functions can be selected:

Activation or deactivation of one or more of these driving or operating aids is naturally indicated in the multifunction display. The new functions are operated via a separate console immediately adjacent to the steering wheel.

Hitching up accurately, approaching with full control and docking smoothly are manoeuvres during which trucks with an automated clutch have previously required a particularly sensitive foot on the accelerator. These situations are now made noticeably easier for the driver with Mercedes Power-Shift.

In manoeuvring mode, the transmission control unit assigns all the tasks previous­ly dependent on skilled use of the accelerator and clutch to the accele­rator alone. This means that throughout almost the entire pedal travel, engage­ment and disengagement of the friction clutch is finely metered while the engine speed is limited to a maximum of 1000 rpm.

Manoeuvring mode is activated at the touch of a button. The resulting ability to shift directly from first gear to reverse gear raises the manoeuvring quality of an Axor with Mercedes Power-Shift to the level of highly skilled drivers interacting perfectly with a manual or Telligent gearshift.

Even roadgoing trucks can get stuck somewhere – more often than already stressed truckers would like. As professionals know all too well, the surfacing at loading and unloading points is not always a masterpiece of the roadbuilder’s art. Help is now at hand with Mercedes Power-Shift. With rocking mode activated, the driver can now do exactly what he is accustomed to doing in a truck with a con­ven­tio­nal, foot-operated clutch: let the clutch bite slowly, ease off, let it bite again, ease off, and so forth.

With Mercedes Power-Shift he does not need to depress, release and depress a clutch pedal, but merely to open and close the throttle. Usually this rocking action develops a momentum of its own after just a few repetitions, enabling the truck to free itself with one final burst. It is precisely this rapid clutch disengagement that Mercedes Power-Shift makes available in rocking mode when the accelerator is released. What is frowned upon in the normal shift programme is a great help here.

With the introduction of the new-generation constant mesh transmissions, Mercedes Power-Shift now offers four instead of the previous two reverse gears. The fast reverse gears can be particularly helpful when longer stretches need to be covered in reverse owing to a lack of turning space.

Typical examples of this are semitrailer tipper operations in motorway construc­tion, where large quantities of bulk products need to be brought to the site within a very short time, and turning manoeuvres on the freshly laid road surface are strictly forbidden.

Mercedes-Benz not only scores where drive and transmission technology is concerned, but also when it comes to safe, comfortable and economical braking. After all the Axor, the specialist for short-radius and regional long-distance operations, is equipped with the same high-performance braking system with which Mercedes-­Benz set a new standard in safety and operating costs with the introduction of the Actros more than ten years ago. At that time Mercedes-Benz once again revolutionised the development of brake technology: the Actros was the world’s first truck whose standard equipment included disc brakes all-round, as well as an electronically controlled, high-pressure braking system.

No less than 15 years earlier, in 1981, the former Daimler-Benz AG was the first manufacturer to introduce the anti-lock braking system (ABS) for Mercedes-Benz heavy trucks and buses. The advent of ABS in heavy commercial vehicles as one of the most outstanding safety developments in the history of the automobile occurred just three years after its debut in Mercedes-Benz passenger cars.

The Telligent braking system consists of a dual-circuit compressed air braking system with an operating pressure of ten bar, automatic wear adjustment, ABS, a compressed air dryer and, last not least, electronic brake control. The high operating pressure makes for a fast braking response, adequate braking power and a valuable time-gain for the driver when braking .

The advantages of disc brakes have already been amply demonstrated in the Mercedes-Benz trucks which are already in the market. High thermal resistance, favourable fading characteristics, low weight, an easily metered braking effect, uniform responsiveness, low hysteresis and insensitivity to fluctuations in friction are just some of the well-known advantages.

The performance, operating comfort and economy of the braking system are enhanced even more by the Telligent braking system. Thanks to electronic brake control, and almost irrespective of the vehicle load, the Axor brakes as comfortably as a passenger car. In any load conditions, the brake pedal travel is always translated into the same deceleration for the vehicle or combination.

The current generation of the Mercedes-Benz Axor offers an even greater safety potential, for example with Brake Assist (BAS) complementing the braking system as standard. This interprets the speed with which the brake pedal is operated as an emergency braking command, and instantly builds up the maxi­mum brake pressure. In addition, the likewise standard drive and braking cruise control system keeps the vehicle speed constant both on the level and on down­hill gradients – the latter being a very substantial safety feature.

Integration of the auxiliary brake is another component of this high-tech package. This means that when operating the brake pedal, the Axor driver activates both the service brake and the auxiliary brake(s). The aim of combining all the on­board braking systems is of course to reduce wear and tear to the service brake even further, by substituting some of the braking performance it is required to deliver with wear-free engine braking.

The brakes are activated in sequence: first the service brake, then the auxiliary brake(s) – a very substantial difference from other solutions of this kind. The sequence adopted by Mercedes avoids the safety risks associated with the reverse order, not least because of the large variation in axle loads which is inherent to truck/trailer combinations, and the resulting safety risks when braking only one axle on icy or slippery road surfaces.

The start-off assist function with hill holder is another technical highlight of the Telligent braking system which offers definite advantages for the driver. This feature makes moving off on uphill gradients much easier by fully electronically controlled and therefore extremely rapid operation of the pneu­matic wheel brake valves. After every operation of the brake pedal to vehicle standstill, the brake pressure is maintained for approx. one second after the brake pedal has been released to prevent the vehicle from rolling backwards. During this interval the driver is able to move off easily by depressing the accelerator, even on gradients. In the case of heavy trailer and semitrailer combinations, this feature also significantly lightens the driver’s workload when manoeuvring slowly in tight spaces. Start-off assist can be switched on or off using a push-button switch.

One of the exclusive options for the Axor is the "Turbobrake", which is available on request to complement the standard auxiliary brake combination consisting of a constantly open throttle valve brake and an exhaust flap brake; at engine speeds above 2000 rpm it develops wear-free, continuous braking performance of 450 kilowatts (612 hp) and can in many cases replace a heavier, more expensive secondary retarder. brake, and can in many cases replace a heavier, more expensive secondary retarder.

The Turbobrake is an add-on to the turbocharger which maximises engine braking performance. The turbocharger has a twin-pipe turbine intake and is fitted with a wastegate for the "hot" side of the turbine, as well as an axial slide valve bearing a so-called turbo ­brake guide mesh.

The Turbobrake works as follows: under engine braking, the dense guide mesh is moved in front of the turbine rotor and leads to a high exhaust counterpressure. The result is an increase in the airflow through the engine via the compressor, which in turn increases the braking performance from 280 to 450 kW, almost doubling it. The wastegate prevents any overload on the engine. The brake guide mesh is withdrawn from the turbine rotor when the engine is under load.

The optional Turbobrake means that the classic exhaust flap can be omitted, as it would be counter-productive in this case. The constantly open throttle valve is however still desirable with the Turbo­brake, though it is activated hydraulically rather than pneumatically when acting together with the Turbo­brake.

In recent years Mercedes-Benz has caused quite a stir with its optional electronic assistance and safety systems. To ensure that accidents can be actively preven­ted, Mercedes-Benz also offers a number of these safety systems for the Axor. They help the driver to master critical situations, and include Telligent stability control, Telligent Lane Assistant, Telligent proximity control and Telligent roll control for two and three-axle trucks.

Telligent stability control is an active safety system which reduces the risk of skidding for semitrailer combinations when negotiating bends or taking evasive action. It does this by specifically controlling the braking forces at each individual wheel in dynamically critical situations where the vehicle develops a tendency to understeer or oversteer. The engine output is also reduced. Possible "jack-knifing" by the semitrailer is simultaneously prevented by finely metered brake pressure, even if the semitrailer is still equipped with a conventional, pneumatic braking system.

Should the semitrailer reach the point of overturning without the driver noticing on extended bends – for example on motorway slip roads – or during fast lane-changes, the speed of the combination is automatically reduced until stability has been fully regained. Within the physical limits this considerably reduces the risk of a semitrailer roll-over. Telligent stability control corresponds to the ESP system used in passenger cars, though with extended functions suited to its use in trucks.

Lane assist warns the driver when the vehicle is at risk of leaving the road unintentionally. This can be caused by attention lapses of all kinds, e.g. reaching for the radio or telephone. The centrepiece of the system is a small camera behind the windscreen which monitors the road immediately in front of the vehicle. If the vehicle shows a tendency to leave its lane unintentionally, a penetrating rumble-strip noise is emitted by the left or right-hand radio loudspeakers, causing the driver to countersteer intuitively. Confirmed findings by the DaimlerChrysler research departments show that the driver automatically steers his vehicle back to the centre of the lane when hearing this noise.

Telligent proximity control keeps the vehicle at a safe distance from the vehicle ahead. Within defined limits, the driver is able to set the desired safety gap him­self. The control strategy always ensures compliance with the minimum gap of 50 m prescribed for heavy trucks on German motorways at speeds exceeding 50 km/h. Telligent proximity control regulates the set distance by staged inter­vention (deceleration, auxiliary brake, service brake). This also applies when another road user suddenly cuts in and decelerates in front of the vehicle. Once the traffic density in front of the vehicle lessens again, the cruise control function accelerates the vehicle back to the speed selected by the driver.

The Telligent roll control system optionally available for Axor truck chassis provides situation-related shock absorber responses. Conventional shock absor­bers with their predefined characteristic curves for the rebound and compression stages are not able to cover all the varied requirements of day-to-day truck operations. They could certainly respond more softly during normal driving, but should be harder – and therefore provide more safety – when negotiating bends and during lateral acceleration (e.g. fast lane-changes and heavy braking).

Telligent roll control automatically adapts the damping response to the relevant driving situation and the nature of the road surface. Roll control operates on the following technical principle: sensors detect the vertical movements at the front and rear axle, the brake pressure, the load conditions, movements of the accelera­tor and the vehicle speed. These values are registered and evaluated by the cen­tral control electronics, converted into control signals and sent to the shock absor­bers, which are equipped with an electrically controllable valve. The damping characteristics are modified within milliseconds, so the vehicle responds immedia­tely. This improves handling safety, ride comfort and cargo protection, while also reducing wear and tear on the road surface, the tyres and other vehicle components.