Automatic transmissions are commonplace in modern vehicles, but like all technological breakthroughs, they were met with scepticism early in their inception. Early slush boxes had question marks against their reliability, durability, and fuel economy; all unavoidable issues due to the inherently complex design of these transmissions versus a traditional manual transmission.
Over the years, increasing human dependency on automation and not to mention congestion of roads have made automatic transmissions ever more appealing despite their initial shortcomings, and automakers were challenged to simply make better gearboxes to meet consumer needs. Most have stuck with refining the traditional stepped automatic transmission, whilst some have explored alternative solutions, with the CVT and dual clutch transmission being two of the most prominent examples that come to mind.
Each of the three different types of automatic transmissions have their own pros and cons, and selecting between the three often boils down to a preference to the type of driving experience that they offer. Dual clutch transmissions are typically suited in delivering sportier driving sensations due their ability to switch gears in lightning quick time and also because they have a more direct feel like a manual transmission.
The biggest drawback about dual clutch transmissions is that they generally lack low speed smoothness, and this is where CVTs excel. Due to its belt-driven design, CVTs are inherently smooth and greatly suited for applications that place high priority on refinement. Unfortunately, CVTs lack the mechanical robustness for high torque applications and their stepless driving sensations are not to everyone’s tastes, especially enthusiasts.
Drivers from different regions have different preferences, and it was found that the driving characteristics of CVTs are most highly-prized in the Japanese market that prioritizes low-speed smoothness and refinement. Europeans prefer the sportier sensations of dual clutch gearboxes while Americans are still partial to the traditional torque converter automatic transmission. A car maker that is able to blend all these characteristics into one transmission would steal a very important march in transmission development.
Mazda’s new 6-speed automatic transmission, dubbed SkyActiv-Drive, is in essence a traditional stepped automatic transmission with a torque converter, but it is one that has been given an ambitious engineering brief to deliver the best virtues of the three types of automatic transmissions available without increasing complexity or weight. Like all other aspects of SkyActiv technology, Mazda essentially went back to the drawing board and rethought the automatic transmission from scratch.
With admirable determination, Mazda took on the various issues of the automatic transmission one-by-one and convincingly addressed them with simple and elegant solutions. Excessive torque converter slippage that is the root cause of an automatic transmission’s performance and economy deficits is mitigated with a lock-up clutch.
That in itself is nothing new, but compared to existing designs, the SkyActiv-Drive has an exceptionally wide lock-up range that ensures a mechanically direct transmission of power available for longer periods of time. As such, instantaneous response is guaranteed whenever the accelerator is floored.
An advanced mechatronics module helps facilitate faster, smoother and more precise gear changes, thereby delivering the main selling point of a dual clutch gearbox without sacrificing the ability to make smooth start-ups from standstill. Actuators controlling the transmission’s hydraulic system are operated by highly responsive direct linear solenoids.
The highly-innovative nature of this transmission is further highlighted by the fact that Mazda was able to achieve all that it set out to do by designing a transmission that is lighter and more compact than the unit it replaced. Mazda’s internal data points to fuel savings of 4-7% contributed by this transmission, and countless reviewers have praised its impressive smoothness in operation. This is a truly remarkable transmission with benefits that are both measurable and subjective.