
Automobile transmission system components include: 1. Transmission mechanism: consisting of manual transmission and automatic transmission; 2. Differential: a device that resolves speed differences between left and right wheels; 3. Drive shaft: the mechanism that transmits power from the transmission system to the differential, thereby generating driving force; 4. Engine configuration: including front-engine front-wheel drive, front-engine rear-wheel drive, and mid-engine rear-wheel drive. The function of the automobile transmission system is to transmit the power generated by the engine to the driving wheels of the vehicle, creating driving force that enables the car to move at certain speeds.

Last time I was chatting with a friend at the auto repair shop about the drivetrain, which is essentially the set of components that transfer the engine's power to the wheels. In my car, the power is transmitted like this: first from the engine to the clutch plate—stepping on the clutch in a manual transmission disconnects this link. Then it goes into the gearbox, which acts like a sorting station, dividing the power into different gears. The driveshaft then delivers the power like a courier to the rear axle's differential, and finally, the half-shaft gears distribute the power to the left and right wheels, much like sorters. Front-wheel-drive cars are simpler, skipping the driveshaft altogether and sending power directly through the front axle. Performance car enthusiasts are most concerned about driveshaft strength since high horsepower can easily twist or deform the shaft.

When teaching my apprentices, I often compare the drivetrain to a relay race: the engine is the starting runner, the flywheel takes the first baton and passes it to the clutch, which acts like a relay baton passer that can disconnect at any time; the transmission is the mid-race exchange zone, adjusting the torque relay rhythm through gear sets; the driveshaft, like a long-distance runner, delivers power straight to the rear axle; the differential, as the final runner, is the smartest, allowing the left and right wheels to rotate at different speeds during turns. When off-roading, remember the differential lock is crucial—it can rigidly connect the left and right wheels to synchronize their power and help you escape when stuck.

I remember when preparing for the technician certification exam, the four major drivetrain components were what I memorized most thoroughly: 1. Clutch – the power switch hand, when worn out the car will shake; 2. Transmission – divided into gearbox and CVT continuously variable transmission, the former is durable while the latter is fuel-efficient; 3. Driveshaft – a steel pipe with universal joints, if broken it will clunk when turning; 4. Final drive assembly, including the differential and half-shafts. Front-wheel drive cars have a compact structure but heavy steering, rear-wheel drive cars offer flexible handling but are prone to oversteer, while four-wheel drive is best for off-roading but has higher fuel consumption. Regularly changing transmission fluid can extend its lifespan.

My old pickup truck's drivetrain has been repaired three times: first, the clutch disc wore out, making starts feel like a frog jumping; later, the universal joint on the driveshaft developed excessive play, causing the whole vehicle to vibrate so much above 60 mph that my hands went numb; last year, the differential bearings failed, making a clicking noise when turning. The mechanic said the key to drivetrain maintenance is checking three fluids: transmission oil every 40,000 km, differential oil every 60,000 km, and never mixing power steering fluids. If you hear metal grinding sounds, check the bearings immediately—waiting until they wear through the housing will cost big money. Driving an electric vehicle is simpler now, with direct motor drive eliminating even the transmission.


