Glossary
transmission
The transmission is the gearbox between the engine and the wheels. It matches the engine's narrow speed range to the wide range the vehicle needs, trading revolutions for torque.
The transmission is the gearbox between the engine and the driven wheels. Its job is to match the engine's narrow, fast speed range to the much wider range the vehicle actually needs, which is what lets a car pull away from rest and still cruise at highway speed.
It does that with gears. A manual gearbox uses different pairs of gears, chosen by the driver with the clutch and the shifter; an automatic changes gear through hydraulic pressure and a torque converter. Both make the same trade: a low gear multiplies turning force at the wheels so the car can move off, and a high gear trades that force for speed.
The transmission is not the differential, which sits at the axle and allows the driven wheels to turn at different speeds in a corner, and it is not the clutch, which is what disconnects the engine from the gearbox while you change gear.
Taught in
Related terms
- clutch — The clutch connects and disconnects the engine from the transmission. Press the pedal and the friction surfaces separate, so the engine can keep turning while gears are changed.
Source: Official ASVAB — subtest descriptions (what each subtest asks) and the CAT-ASVAB scored-question counts (accessed 2026-09)