What are the three functions of a transmission?
3 Answers
Transmission functions are introduced as follows: 1. Altering magnitude: It enables substantial changes in both vehicle speed and driving wheel torque. Since driving conditions vary, vehicles require wide-ranging adjustments in speed and torque. However, automotive engines operate within relatively narrow rotational speed ranges, and their torque variation scope is insufficient for actual road conditions. 2. Enabling reverse motion: Typically, an engine's crankshaft only rotates unidirectionally, whereas vehicles occasionally need to move backward. 3. Providing neutral gear: When the clutch is engaged, the transmission can discontinue power output. This allows drivers to release the clutch pedal and leave their seats without stalling the engine.
When my old car was roaring uphill last time, I truly understood the importance of the transmission. Simply put, it does three things: First, it changes torque – when starting on a slope, downshifting to a lower gear makes the engine push the car effortlessly, like switching to a smaller chainring when cycling uphill. Second, it changes speed – shifting to higher gears during highway cruising lowers engine RPM and saves fuel. Third, it reverses direction – engaging reverse gear lets you back up directly without needing to turn around. Especially with manual transmissions, that satisfying 'click' when slotting the gearstick gives you a tangible sense of power being redistributed.
Last time at the repair shop, the mechanic pointed at the transmission and called it the car's interpreter. The engine only knows one way to deliver power at a fixed RPM, but driving requires multiple states. The transmission's core function boils down to three conversions: reducing speed while increasing torque (like amplifying wheel power during heavy-load starts), increasing speed while reducing torque (lowering RPM for fuel efficiency at high speeds), and most crucially—reversing the output shaft direction for backing up. Without this function, you'd literally have to push the car backward. Watching the disassembled gearset at the shop revealed planetary gears transforming like a Transformer, creatively repurposing the engine's single RPM into versatile performance.
