Chapter 9: The Drive Train part 2

Chapter 9: The Drive Train part 2
    Chapter 9: The Drive Train part 2

    Chapter 9: The Drive Train part 2


    The Difference Between a Manual and Automatic Transmission:
    A manual transmission (which is also called a standard transmission) uses conventional gears. All of these gears are turning at all times when the engine is running and the clutch is released. When a gear is selected with the gear shift, the gear is being attached to the output shaft. Then to change gears, the clutch is depressed and the next gear is selected which attaches that gear to the output shaft. The gears are manually selected. 

    An automatic transmission uses sun and planet gears. A sun and planet gear set has a central sun gear with planetary gears (typically three or four) located around the sun gear. These gears can rotate, turn or hold to create different speeds and directions. To select the gears there are multiple clutch packs and/or bands that are hydraulically applied by a valve body to control gear selection. 

    Types of Automatic Transmission Fluid:
    There are 30 or more different types of transmission fluid for today s modern vehicles. 
    All the fluids look the same. Refer to the owner s manual to select the correct fluid. 
    Aftermarket suppliers make fluids that are compatible with multiple different vehicles. When choosing aftermarket fluids, be sure that the specified fluid in the owner s manual is listed on the aftermarket bottle.

    Lubricants Used in Standard Transmission:
    The lubricants used in a standard (or manual) transmission on modern vehicles have multiple types of fluid. Be sure that the fluid installed in the vehicle meets the manufacturer’s specifications.

    Lubricants Used in Differentials:
    Most differentials use conventional 80-90 gear oil. The 80-90 numbers indicate the weight and viscosity of the oil. (These are similar to the API and SAE discussed in Chapter 5). Some vehicles require special fluids. Be sure the fluid meets the manufacturer s specifications. Limited slip differentials may require an additional additive.

    The Difference Between Front Wheel Drive, Rear Wheel Drive & Four Wheel Drive:
    The main differences between front wheel, rear wheel, and four wheel drive are the position of the drive train parts and where the drive train transmits the energy.

    A front wheel drive vehicle incorporates a differential and a transmission into one piece, called a transaxle. The transaxle transmits power from the engine to the front wheels. 

    A rear wheel drive vehicle transmits engine power through a transmission to the drive shaft, and then to a differential in the rear of the vehicle. 

    One type of four wheel drive vehicle transmits power through a transmission, and then to a transfer case, which distributes the power through the front and rear drive shafts, then to the front and rear differentials. Another type of four wheel drive has a front transaxle and rear differential. 

    (The diagrams in this book are not the only configurations. A vehicle can have a rear engine with all three drive types, or even a mid-mounted engine.) 

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