Drivetrain and Transmission
Manual and automatic transmissions, double clutching, torque converters, and clutch systems.
- Compare manual and automatic transmission operation in heavy trucks
- Explain driveshaft function, U-joint operation, and causes of driveline vibration
- Describe double clutching technique and clutch system components
Lección 1
Transmission Types and Operation
Manual vs Automatic Transmissions
Heavy trucks use two main transmission types. A manual transmission requires the driver to select gears using a shift lever and clutch pedal. An automatic transmission uses a torque converter to couple the engine to the transmission and shifts gears automatically through hydraulic controls and electronic logic.
Manual Transmission
Coupling: Mechanical clutch
Shifting: Driver-selected
Types: 10, 13, or 18-speed
Requires: Double clutching skill
Automatic Transmission
Coupling: Torque converter
Shifting: Computer-controlled
Advantages: Easier operation, consistent shifts
Common: Allison series
The transmission range selector selects forward, neutral, and reverse ranges. In automatic transmissions, it also controls the number of available gear ranges. The transmission ECU determines shift points based on throttle position, vehicle speed, grade, and load.
Exam Tip
When asked what type of transmission uses a torque converter, the answer is automatic transmission. Manual transmissions use a mechanical clutch disc.
An automatic transmission uses a torque converter for fluid coupling between engine and gearbox. The transmission range selector selects forward, neutral, and reverse ranges. Manual transmissions require the driver to shift gears using a clutch.