Toyota Introduction to Manual Transmissions and Transaxles

Section 1 Introduction to Manual Transmissions & Transaxles Learning Objectives: 1. Identify the purpose and operation of transmissions. 2. Describe torque and torque multiplication. 3. Determine gear ratios. 4. Identify spur and helical gears, and describe the difference between the two. Manual Transmissions & Transaxles - Course 302 1-1 Section 1 Drivetrain Introduction to Manual Transmissions & Transaxles Energy produced in the engine is transmitted to the drive wheels through the drivetrain. The components that make up the drivetrain include: a clutch mechanism, transmission, propeller shaft, differential and axles. The drivetrain allows the driver to control power flow using engine torque and allows the vehicle to move from a stop to cruising speed while maintaining engine speed within it's most efficient power band. A drivetrain can transmit engine power to the rear wheels, front wheels or all four wheels. When the drivetrain delivers power to the rear wheels, it is referred to as front engine rear drive (FR); when it delivers power to the front wheels, front engine front drive (FF); and when it delivers power to all wheels, four wheel drive (4WD). Front Engine Rear Drive (FR) Drivetrain A front engine rear drive (FR) drivetrain delivers power from a front mounted engine through the transmission and rear differential to the rear wheels. Front Engine Front Drive (FF) Drivetrain A front engine front drive (FR) drivetrain delivers power from a front engine through the transaxle and differential to the front wheels. (This configuration is essentially the same for a rear mounted engine with rear wheel driver)

The transmission converts engine speed into the needed torque output required for different driving conditions. High torque is needed to start off from a stop and engine torque must be greatly multiplied at low engine RPM. High torque for climbing hills is provided by increased engine RPM and torque multiplication. Less torque is required to keep the vehicle moving at intermediate or high speeds, allowing engine speed to be reduced.

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