7g Tronic Manual
In the interests of improving driving comfort, Mercedes-Benz began the development of transmissions to reduce the driver's workload as an early stage. As early as 1930, the Model 770 'Grand Mercedes' was equipped with a semi-automatic, suction-operated linkage for the overdrive. This milestone was a first step by Mercedes-Benz on the way to an automatic transmission. However, the first really automatic transmission, a three-speed torque converter transmission, offered by Mercedes-Benz for the Model 300 'Adenauer' from autumn 1955 was an American design by Borg-Warner. In 1972 Mercedes-Benz changed over to a newly developed generation of automatic torque converter transmissions, which established themselves as three or four-speed transmissions in all model series by 1973. From 1979 Mercedes-Benz introduced a newly developed generation of automatic torque converter transmissions which excelled with high efficiency, a wider torque conversion range and reduced fuel consumption.
The version for the most powerful engines was now also equipped with four rather than three gears. In 1989 a variant with five speeds was added for the six-cylinder models. In 1995 the new five-speed automatic introduced by Mercedes-Benz for the V12 and V8 models was a major milestone in automatic transmission development. For the first time it combines an electronic control system and a torque converter lock-up clutch. The result was significantly improved ride comfort and reduced fuel consumption.
The transmission’s computer automatically adapted its gearshifting characteristics to the current driving situation and the individual wishes of the driver. In addition the electronics adjusted the shift points on uphill or downhill gradients, preventing sudden gear changes that could unfavourably affect vehicle handling. It also excelled by having two transmission modes and being of modern lightweight construction. In 1998 an improved variant of the five-speed automatic transmissions entered series production for the new S-Class (220 series), featuring a further development in the form of Touchshift. In 2003 Mercedes-Benz reached new heights with the 7G-TRONIC, the world's first electronically controlled seven-speed automatic torque converter transmission for passenger cars. This made Mercedes-Benz models more economical and faster in acceleration.
In addition this transmission significantly improved gearshift comfort. Having seven ratios allowed small increases in engine speed – making it easier to ensure the right ratio for the current driving situation. At the same time the ratio spread between the lowest and highest gear became larger. This reduced the average engine speed – a plus point in terms of both fuel consumption and noise comfort. During rapid downshifts (kick-down) the individual gears were no longer necessarily shifted in sequence. Instead the control system of the new 7G-TRONIC transmission skipped individual gears if necessary, e.g.
Shifting from seventh directly to fifth gear and then to third gear. Depending on the driving situation, this meant that the previous four gearshift operations required to accelerate the car rapidly during kick-down were reduced to two. At the same time the quality of gear shifts was greatly improved. They became much smoother and hardly perceptible, particularly in the upper gears. From 2008 the Mercedes-Benz SL became available with 7G-TRONIC Sport and steering wheel shift paddles. This featured a double-declutch function activated during manual downshifts.
This not only produced a very sporty sound, but was also in the interests of safety and comfort, as the double-declutching synchronised the crankshaft and transmission speeds. The advantage: gear shifts became even smoother, and typical load cycle reactions were noticeably reduced.
In 2009 the AMG SPEEDSHIFT DCT 7-speed sports transmission appeared for the SLS AMG. This excelled with fast gear changes and practically no interruptions in tractive power. Four different transmission modes were available to the driver: the fuel-efficient 'C' (Controlled Efficiency), 'S' (Sport), 'S+' (Sport plus) and 'M' (Manual). An automatic double-declutching function was active in Sport, Sport plus and Manual mode, and all modes could be conveniently operated via a rotary control in the AMG DRIVE UNIT.
7g Tronic Manual
The RACE START function allowed optimal traction – as did the mechanical differential lock integrated into the compact transmission housing. In 2010 Mercedes-Benz presented a further development of its seven-speed automatic transmission with the new-generation CL-Class (216 series): 7G-TRONIC PLUS. This was even more comfortable, faster and more economical than the first-generation 7G-TRONIC. An engine connection with further reduced torque converter slip and significantly lower internal power losses optimised the efficiency. The various innovations ensured that in ECO mode, there was a reduction in engine speeds that greatly contributed to fuel savings. In 2012 the new SL was likewise launched with the 7G-TRONIC PLUS.
New feature: the Roadster was the first Mercedes-Benz to be equipped with the newly developed DIRECT SELECT gearshift in the centre console, a feature reminiscent of a high-quality joystick. In this way the premium brand established a completely new generation of centre gear shifts for vehicles with shift-by-wire transmission technology. The latest development stage of the 7G-TRONIC PLUS entered use in 2013, in the E 300 BlueTEC HYBRID. Here Mercedes-Benz combines the 2.2-litre four-cylinder diesel engine developing 150 kW (204 hp) with a powerful hybrid module.
Mercedes 7g Tronic
The 20 kW electric motor is integrated into the transmission's torque converter housing. The electric motor assists the diesel engine when accelerating (boosting), and is used to recuperate braking energy in generator operation. At the same time it is suitable for purely electric driving. In 2004 Mercedes-Benz introduced the AUTOTRONIC system developed in-house as an optional extra for the A-Class (169 series). AUTOTRONIC operates on the principle of a 'continuously variable transmission' (CVT), in which the ratios are varied continuously using a pulley wheel variator.
7g-tronic Manual Mode
Accordingly, it does not employ the paired gear wheels normally used in automatic transmissions. The main advantages of AUTOTRONIC compared with a conventional manual transmission are improved ride comfort, extra flexibility and quicker acceleration. In 2011 a further Mercedes-Benz automatic transmission celebrated its debut in the B-Class: the 7G-DCT dual clutch transmission. Extremely compact, highly adaptable to engine speeds thanks to seven gears and start/stop capable by virtue of an electric oil pump, this transmission performs gear shifts with no interruption in tractive power and combines the comfort of an automatic with the efficiency of a manual transmission. 7G-DCT is an automated three-shaft manual transmission consisting of two partial transmissions, each with its own clutch.
Both clutch actuation and gear changing are fully automatic without any interruption in tractive power, It allows both exceptionally comfortable and dynamic driving. The new 4MATIC for the compact models also combined with 7G-DCT.
The special feature of this technology is that the power flow to the rear drive train is provided by a compact power take-off unit (PTU) which is fully integrated into the main transmission and supplied with lubricant from the latter's oil circuit. This configuration gives rise to substantial weight advantages over competitor systems that branch off power by means of an add-on component with its own oil circuit.
The models A 45 AMG, CLA 45 AMG and GLA 45 AMG feature a particularly sporty variant of this drive technology. The AMG SPEEDSHIFT DCT 7-speed sports transmission is specifically configured for the world's most powerful four-cylinder engine, and thrills with its additional functions of double-declutching and RACE START.