SKYACTIV Part 2: The Transmission

The Ideal Transmission for Perfect Control.

The transmission plays a huge part in fuel efficiency and driving performance. The "ideal transmission" gives you perfect control over your car. Mazda's transmission systems promise precise handling as well as improved fuel efficiency. 

SKYACTIV-Drive

SKYACTIV-Drive Transmission

Mazda's SKYACTIV-DRIVE combines the advantages of conventional automatic transmissions, continuously variable transmissions, and dual clutch transmissions. The main key requirements for automatic transmissions are:

• Good fuel economy
• Quick start-up
• Direct feel
• Smooth shifting

As shown in the image below, between each of the transmission types, there are advantages in each category. But SKYACTIV Drive combines the advantages in each of the categories.

Advantages of each transmission type

Automatic transmissions have no clutch that disconnects the transmission from the engine when the vehicle is at a complete stop. This is where the torque converter comes in. The torque converter is a type of fluid coupling which allows the engine to spin somewhat independently of the transmission (hence why you are able to come to a complete stop without stalling the engine in an A/T).

The torque converter consists of a turbine, stator, pump and transmission fluid. The pump is directly connected to the engine, and is similar to a centrifugal pump - as it spins, fluid will be pushed outwards due to centrifugal force and there will be increased pressure. This rotation of the pump creates a swirl in the liquid, and this high energy fluid coming out of the pump turns the turbine (which is connected to the transmission). This is how the engine power is transferred to the transmission. There is a transfer flow of the fluid in the torque converter, which allows this transfer of power between the engine and the transmission. The stator redirects the fluid returning from the turbine before it reaches the pump again.

In normal operation, you will find that the turbine turns slower than the pump - this is due to energy loss in the fluid. To improve efficiency, there is a lockup clutch which will lock the 2 halves of the torque converter to improve fuel economy and direct drive feel that is equivalent to a manual transmission. 

The Basics of How a Torque Converter Works

SKYACTIV-MT

SKYACTIV-MT Transmission

Inspired by the widely loved MX-5, the 6-speed SKYACTIV-MT is smaller, lighter and stronger - featuring a short shift throw to achieve an incredible light, crisp feel, just like a sports car.  

Short stroke and increased lever ratio

To achieve this quick shift feel, both a shift shift-lever stroke and light shift effort had to be achieved. Mazda's engineers reduced the stroke length by 5mm to achieve a short, 45mm internal stroke. Considering the principle of levers, a lever with a short stroke requires more effort to move it, thus a larger gear lever ratio is needed but, in return, it reduces the internal stroke. To overcome this, Mazda's transmission engineers developed a small module spline that allows for exceptionally precise synchronizer and torque transmissions. 

Mazda's engineers intentionally created moderate resistance at the initial point of gear change, but after that, the gear shift is amazingly smooth - this is Mazda's shift feel. 

Shorter secondary shaft and removal of reverse idle shaft.

In pursuit of the ultimate shift quality, Mazda's engineers reexamined gear configurations to achieve further weight reduction (they were able to reduce roughly 3kg!) and higher efficiency. Over 30 different configurations for a triple shafted gear train with a common gear for 2nd and 3rd were developed. Based on this selection, the lightest structural specifications were selected from over 10,000 alternatives. Mazda's engineers reviewed the function of each component and commonization of the 1st and reverse was adopted. With these slight changes, they were able to reduce the length of the secondary shaft by 20% as well as remove the reverse idle shaft. 

Mazda MX-5 Miata

Mazda's devotion and commitment to delivering pure "Jinba-Ittai" (horse and rider as one) driving exhilaration can be seen and felt in the products. Every part works seamlessly as a whole to celebrate and deliver the true joy of driving. Stay Tuned for Part 3: The Body!