Dual-Clutch and CVT Transmissions

How DCT and CVT boxes work and how they fail.

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What you will learn

Describe DCT operation
Describe CVT operation
Recognise typical complaints

A dual-clutch transmission (DCT) uses two clutches and two input shafts so the next gear is pre-selected, giving fast shifts without a torque converter. The mechatronic unit controls the clutches and the gear selects.

A continuously variable transmission (CVT) uses a belt or chain running between two variable-width pulleys, providing an infinite ratio range. Both types depend on precise hydraulic/electronic control, and both can judder, hesitate or slip when fluid, clutches, sensors or adaptions are wrong.

Type	Strength	Typical fault
DCT	Fast shifts, efficiency	Clutch judder, mechatronic faults
CVT	Smoothness, efficiency	Belt/chain wear, judder, overheating

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Key points

DCT: two clutches, pre-selected gears.
CVT: variable pulleys and a belt/chain.
Fluid, adaptions and mechatronic control decide behaviour.

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Key points

A DCT uses two clutches and two input shafts
A CVT uses a belt/chain and variable pulleys
Both rely on mechatronic control and adaptions

All values shown are training examples. Real thresholds depend on the manufacturer, engine, temperature and system — always confirm with the vehicle service documentation.