Transmission

The transmission (or gearbox) is one of the most critical mechanical assemblies in a vehicle’s drivetrain system. Its primary role is to modulate the rotational speed and torque delivered from the engine to the driven wheels, ensuring the engine consistently operates within its optimal, most fuel-efficient power band across various driving scenarios—including moving off from a standstill, hill climbing, high-speed cruising, or reversing. Whether in conventional internal combustion engine (ICE) vehicles or modern new energy vehicles (NEVs), the gearbox (or reduction gear assembly) acts as a crucial bridge for power transmission and gear ratio adaptation.

Core Classifications and Operating Principles

Automotive transmissions are primarily categorised into the following mainstream types:

Manual Transmission (MT) vs Automatic Transmission (AT / DCT / CVT):

Manual Transmission (MT): Operated manually via the gear lever and clutch pedal to engage different gear ratios mechanically, offering a straightforward mechanical layout, the highest power transfer efficiency, and engaging driver involvement.

Torque Converter Automatic Transmission (AT): Pairing a hydraulic torque converter with planetary gear sets, it automatically executes smooth, seamless gear changes based on throttle input and road speed, delivering an ideal balance of ride comfort and durability. 

Dual-Clutch Transmission (DCT): Utilizing twin clutches with pre-select gear logic, it delivers ultra-fast shift times and drivetrain efficiency comparable to a manual gearbox.

Continuously Variable Transmission (CVT): It varies drive ratios seamlessly through a steel belt running between variable-diameter pulleys, providing jerk-free power delivery and exceptional fuel economy.

Safety Operating Guidelines and Mechanical Limits

Never engage P (Park) or R (Reverse) while the vehicle is still in motion or rolling forward/backward (Prohibiting Shifting to P or R Before Coming to a Complete Stop): 

The transmission’s internal parking pawl (Park lock mechanism) and reverse gear are subjected to extreme mechanical shear stress when countering dynamic vehicle momentum. Improper manoeuvres such as "engaging Park while moving" or shifting abruptly between drive modes at speed are strictly prohibited. Slapping the gear selector into P before coming to a complete halt can instantly shear or wear down the parking pawl, compromising the parking lock mechanism or causing catastrophic damage to the internal gearbox components.

Never rely solely on continuous foot braking in D (Drive) on long downhill stretches without downshifting for engine braking (Prohibiting Prolonged Braking on Long Downhills Without Engine Braking): 

Sustained, heavy braking causes friction temperatures in the brake pads and brake fluid to spike rapidly, which can trigger severe brake fade or total braking loss. Coasting in neutral (N) or relying purely on the foot brake when descending steep declines must be strictly avoided. On long descents, drivers should proactively shift into Manual mode (M) or select Low gear (L) to exploit engine braking resistance, helping to regulate vehicle speed and prevent brake system overheating.