How Manual Transmission Works
What is a manual transmission and how does it work? Think of a manual transmission as a link or middleman between the engine and the wheels on your car. The engine transmits power through the transmission to reach the drive wheels. It controls the speed and torque needed for your car to handle different driving conditions. In a car with a manual transmission, the driver shifts the gears using the pedals and clutch, while in an automatic transmission, the car does the work for you.
When you’re in first gear, you have lots of torque but not very high speed. This can help your car traverse up a hill using higher torque. On the other hand, the top gear (fifth or six gear) allows your car to reach high speeds, but you have a low wheel torque.
The operation of a manual transmission
- The driver presses on the clutch pedal, which is the third pedal to the left of the brake and gas pedals.
- From the engine, the flywheel transmits power to a clutch disc, which is secured to the transmission input shaft.
- The transmission input shaft rotates the gear assembly. In a constant mesh gear assembly, every gear is in constant motion (hence its name).
- The driver chooses a gear using their gear lever, commonly called the stick shift or stick. If the driver chooses first gear, for example, that specific gear is locked into place by the input shaft.
- When the input shaft begins turning the output shaft, power is routed to it. Again, if the driver chose first gear in the previous step, that specific gear is locked into place. The chosen gear tells the output shaft how quickly to turn.
- From the output shaft, a differential delivers power to the axle that turns the wheels. When shifting to another gear, like from first gear to second, the input shaft will lock the appropriate gear into place on the output shaft, repeating the process over again.
- Fifth or sixth gears are different because they are usually fixed into place, compared to the other four gears, which move freely in constant motion. The top gear turns the output shaft at a higher speed than the input shaft.
- When the driver puts their car into reverse, the input shaft rotates a third shaft of gears instead of the output shaft. This reverse gear, often called the reverse idler or idle gear, rotates the gears on the output shaft backward. So instead of the power running from the input shaft to the output shaft, power runs from the input shaft to the reverse gear to the output shaft.
Automatic transmissions have eclipsed manual transmissions in popularity thanks to convenience. But car owners who prefer manual transmissions often choose them for the level of control they can exert over their car’s performance, which can be a satisfying feeling.