Axle & Drivetrain System | Axle & Drivetrain Information Parts | Video of Axle & Drivetrain


Quick Component Definition Reference


  • Axle bearing: Located at the end of the axle tube and is lubricated by rear differential fluid. When the bearing has worn out, a growling noise is produced usually increasing with speed.

  • Bearing: Allows wheels on a vehicle to spin freely and stay secured to the vehicle. Common faults include grinding, squealing or abnormal noise from tires while driving.


  • Constant Velocity (CV) Axle: CV Axles are commonly  referred to as axle shafts or "half-shafts." An axle shaft is a narrow, pole-like part that connects to a wheel to the gears in the transmission. Axles are part of the system that enables the wheels to rotate. 

  • Constant Velocity (CV) Axle Boot: They are the rubber covers on either flexible end of the drive axles specifically covering the CV-joints to protect them from outside debris such as dust, sand, rocks and water. 

  • Constant Velocity (CV) Joint: These flexible joints allow power to be maintained to the wheels as they turn left, right, up and down going down the road. 

  • Differential assembly: The assembly in the axle that distributes the power from the transmission or transfer case to the front or rear wheels, and also allows the wheels to turn at different rates of speed.

  • Differential service: The rear differential is composed of the rear differential carrier, a ring gear, side gears, planet gears, a pinion gear, pinion shaft and axle shafts. All of these parts are housed in a metal case so that it can be filled with fluid.

  • Front driveshaft: A shaft that connects the transfer case output to the front axle input on 4WD vehicles.

  • Rear driveshaft: A shaft that connects the transmission or transfer case to the rear axle input.

  • Rear differential: The rear differential transmits torque from the transmission to the rear wheels of the vehicle. The rear differential also allows one wheel to spin faster than the other especially when the vehicle is turning.

  • Transfer case: A drive unit located behind the transmission on 4WD vehicles that transfers the single output from the transmission into a front and rear output. It sometimes also includes a Low Range that reduces the ratio out of the transmission through gearing to increase torque but reduce speed.

  • U-Joint: Connected to the driveshift of the vehicle. It allows the shaft to bend while still transmitting power from the transmission to either the front or the rear differential.

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