Electrohydraulic manual transmission
Electrohydraulic manual transmission, also known as a clutchless manual, or automated manual, is a type of automatic and semi-automatic transmission system, closely based on the mechanical internals of a manual transmission, but instead utilizes an electro-mechanical, hydraulic, or pneumatic clutch activation mechanism, which are electronic or computer-controlled. This contrasts to a conventional manual transmission, where the driver operates the clutch manually.
Design / Operation
Gear shifting, clutch actuation, shift-timing, and rev-matching are all under automated control via electronic sensors, computers, and actuators. When shift gears, the driver selects the desired gear with the transmission shift lever, and the electronic sensors and actuators are controlled via connection to the TCU, which will automatically operate the clutch and throttle to match revs and to re-engage the clutch in milliseconds. Most modern implementations of this transmission function in a sequential mode, where the driver can only upshift or downshift by one gear at a time. However, this is not the case for all modern transmissions. For example, BMW's "SMG" and Ferrari's "F1" transmission can skip gears on both downshifts and upshifts, when selecting gears manually via the paddle-shifers.Depending on the mechanical build and design, some automated manual transmissions will automatically shift gears at the right points, while others require the driver to manually select the gear even when the engine is at redline. Despite the superficial similarity, automated manual transmissions differ significantly in internal operation and driver's 'feel' from a manumatic, the latter of which is an automatic transmission with the ability to override the automatic transmission's computer, and actuate shifts manually.
Usage in passenger cars
One of the first passenger car applications of automated manual transmissions was the 1955 Citroën DS, which used a 4-speed "BVH" transmission. This semi-automatic transmission used an automated clutch, which was actuated using hydraulics. Gear selection also used hydraulics, however, the gear ratio needs to be manually selected by the driver. A similar design was used in the 1956 Renault Dauphine, however, this used an electromagnetically-operated clutch system, rather than hydraulic. Beginning in 1963, the Dauphine's semi-automatic transmission shifting was operated via dash-mounted electronic push-buttons. This was connected to an electro-mechanical control unit, which operated both the clutch and shifting, effectively making it one of the earliest automated manual transmissions in history.In 1967, both the NSU Ro 80 and the Porsche 911 used semi-automatic transmission with a vacuum-actuated clutches and hydraulic torque converters. The transmission was a 3-speed in the case of the NSU and a 4-speed for the Porsche. A year later, the Volkswagen Beetle and Volkswagen Karmann Ghia offered a similar 3-speed transmission, marketed as "Autostick". These transmission mechanisms worked via an electric switch connected to the gearshift, in turn activating a 12-volt servo-controlled solenoid, which would operate and disengage the electro-pneumatic vacuum clutch, and allow the driver to shift between gears.
The Isuzu NAVi5 5-speed automatic transmission was introduced in the 1984 Isuzu Aska mid-size sedan. This transmission, originally designed for trucks, was based on a manual transmission with the addition of hydraulic actuators for the gear shifter and the clutch. Initial versions did not allow direct selection of gear ratios, instead only allowing drivers to lock out higher gears. Later versions added a manual mode, allowing the driver to control the gear selection.
Several companies owned by Fiat S.p.A. were influential in the development of automated manual transmissions. Ferrari's involvement with automated manual transmission began with the 7-speed semi-automatic transmission used in the 1989 Ferrari 640 Formula One racing car. In 1992, the Ferrari Mondial T introduced the option of a "Valeo" 5-speed semi-automatic transmission. This transmission used an electro-mechanical actuator to automatically operate the clutch, while the gearshift mechanism was a standard H-pattern shifter operated as per normal transmissions. In 1997, the Ferrari F355 became available with an "F1" 6-speed transmission, which uses paddle-shifters located behind the steering wheel or can be driven in a fully automatic mode. The F355's successors offered similar transmissions, until the company switched to a dual-clutch transmission for the Ferrari 458 in 2009.
Sister company Alfa Romeo introduced the related "Selespeed" 5-speed automatic transmission for the Alfa Romeo 156 in 1999. This was followed by Maserati's 2001 introduction of the related "Cambiocorsa" 6-speed automatic transmission in the Maserati Coupé.
BMW's involvement with automated manual transmissions began in 1993, when the "Shift-tronic" 6-speed semi-automatic was offered on the Alpina B12 coupe. Using an automated clutch paired to a standard H-pattern shifter, the transmission was supplied by LuK and fitted to less than 40 cars. Mass-production of automated manual transmissions began for BMW in 1997 with the introduction of the "SMG" 6-speed automatic transmission in the BMW E36 M3 coupe. Although the name "SMG" was an abbreviation of "Sequential Manual Gearbox", the transmission internal were as per a typical manual transmission, not a true sequential manual transmission. The SMG was replaced by the SMG-II when the E46 M3 was introduced in 2000. BMW's final AMT was the 7-speed SMG-III used in the 2004-2010 BMW E60 M5 and related BMW E63 M6. The SMG-III could achieve a shift time of 65 milliseconds in its most aggressive mode
From 2002 to 2007, the Toyota MR2 was available with an "SMT" 6-speed automated manual transmission.
Brands within the Volkswagen Group have typically used dual-clutch transmissions instead of automated manual transmissions, however a 6-speed "E-gear" automated manual transmission was introduced for the 2004 Lamborghini Murciélago. and Lamborghini Gallardo. The E-gear was used on the successors to the Murciélago and Gallardo, and it was also available on the 2007-2012 Audi R8, marketed as the "R-tronic" transmission.