What is the Difference Between a Transmission and an Engine?

[VonJoanna]

Transmissions and engines differ in nature and function. Below are the specific details: Different in nature: The engine is the power source of a car. Most car engines are thermal power devices, referred to as thermal engines for short. The transmission changes the transmission ratio, expanding the torque and speed range of the driving wheels. The car engine is the device that provides power to the car, serving as the heart of the vehicle, determining its power, fuel efficiency, stability, and environmental performance. Depending on the power source, car engines can be categorized into diesel engines, gasoline engines, electric vehicle motors, hybrids, etc. Different in function: The transmission can change the transmission ratio, expanding the range of torque and speed variations of the driving wheels. The engine is the device that provides power to the car.

[OAddyson]

When I first bought a car, I couldn't tell the difference between the transmission and the engine either. Later, a friend explained it to me. Simply put, the engine is the heart of the entire car. It burns gasoline or diesel to generate power, just like how a person needs to eat to run. The transmission, on the other hand, is like a gear system responsible for adjusting the power output from the engine and transmitting it to the wheels, allowing the car to start smoothly or speed up quickly. For example, when starting slowly, the transmission downshifts to provide more torque, while at high speeds, it upshifts to save fuel. The difference is huge: the engine only generates power, but the transmission fine-tunes that power. If the engine fails, the car won't start; if the transmission fails, the car can start but won't move or will experience jerky gear shifts. I also learned how they work together—for instance, in heavy traffic, the transmission constantly shifts gears to protect the engine, while at high-speed cruising, both operate efficiently. Maintenance is separate too: the engine needs oil changes, and the transmission requires periodic replacement of specialized fluid. Remembering this can make driving safer and prevent minor issues from turning into major repairs.

[BrandonDella]

I've been driving for over a decade, and the core difference between the transmission and engine is: one creates power, the other transmits it. The engine converts fuel into power in the combustion chamber, driving the crankshaft to rotate; the transmission then adjusts that rotational speed, matching vehicle speed and road conditions through gear sets. They can't swap roles, just like the heart pumps blood but doesn't determine flow direction, while the brain decides flow direction but doesn't pump blood. In daily use, if the engine has issues, like ignition system failure, the car won't start; transmission problems such as clutch slippage result in the engine roaring during acceleration but slow speed. I've also noticed their close interaction—for example, when climbing a hill, the transmission automatically downshifts to ease the engine's burden; on flat roads, it maintains steady RPMs for fuel efficiency. Maintenance differs too: engine oil changes every 5,000 km, while the transmission needs a major overhaul every 100,000 km. Understanding this helps diagnose issues early, ensuring safe and reliable driving.

[DelKhloe]

As a seasoned driver, distinguishing between the transmission and the engine is straightforward. The engine is the power source, generating energy by burning fuel; the transmission is the transmitter, controlling the speed ratio of energy to the wheels. The differences are significant: the engine is needed to start the car and provide driving force; the transmission adjusts that driving force, ensuring smooth acceleration. For example, during startup when the engine has high RPM but insufficient torque, the transmission compensates with a lower gear; at high speeds, the transmission shifts up to maintain stable engine RPM. Their failure symptoms differ: engine failure means the car won't move; transmission issues cause slipping or jerking. In their collaborative operation, the transmission protects the engine from overload; regular maintenance of transmission fluid and engine oil extends their lifespan.