Dual-clutch Transmission—What it is and How it Works

A dual-clutch transmission (DCT) is a type of automotive transmission that has two sets of gears. Each set is operated by a separate clutch to allow for quick and seamless gear changes, even smoother than the automatic transmission.

DCT is neither classified as manual nor automatic transmission, but a hybrid of both. It is commonly known as automated manual transmission (AMT). 

For gear shifting, it operates totally differently. While the process is automatic, it does not involve a torque converter like the automatic transmission. Instead, it has two clutches, one for each set of gears. However, it doesn’t have a clutch pedal nor a stick-shift lever for gear selection like manual transmissions. A DCT relies on the computer to provide smooth, automatic gear shifting.

How does a DCT work?

DCTs have two clutches; one handling odd-numbered gears (1, 3, 5, 7, etc.), while the other handling even-numbered gears (2, 4, 6, 8, etc.). The two sets of gears are used in alternation. When one gear is engaged, the clutch has the next gear ready to go. DCT can switch gears without losing power or requiring the driver to press the clutch pedal. This allows for much faster and more precise shifting than a manual transmission and a greater fuel economy than automatic transmissions.

DCT vs manual transmission

A conventional manual transmission has separate and distinct gear ratios that are selected by the driver. There is a brief moment when the engine is disengaged from the drivetrain while the new gear is selected. This causes a “shock” or “interruption” in the delivery of power to the wheels. If the driver is inexperienced, this can cause the passengers to be thrown forward and back while changing gears.

A dual-clutch transmission is essentially two separate gearboxes in one. The gears are controlled by sophisticated electronics and hydraulics. This means that there is no need to pause transmission output while one gear engages and the other disengages. This allows for extremely fast gear changes with no loss of power.