DRIVE SHAFTS and UNIVERSAL JOINTS

OBJECTIVES Describe purpose and construction of common RWD drive shafts. Describe purpose and construction of common universal joint designs. Importance of driveshaft balance. Explain natural speed variation. Describe the canceling universal joint angles.

INTRODUCTION Drive shaft - transfers power from trans to differential. Drive shaft is made from seamless steel tubing with yokes at each end. Some vehicles use two piece drive shafts. Four-wheel-drive use two drive shafts. Some axle shafts are made like drive shafts.

DRIVE SHAFT CONSTRUCTION Typical universal joint and yokes.

DRIVE SHAFT CONSTRUCTION As the differential travels up and down U-joint angle changes. The distance between trans and differential also changes. U-joints permit change in angle. Slip yoke allows change in length. Drive shafts have a natural tendency to vibrate.

MOVEMENT

Types of Drive Shafts Hotchkiss - External shaft and U-joints. Can be either one or two piece. Torque tube - drive shaft is enclosed. Ridged shaft. Torque tube - Flexible shaft.

UNIVERSAL JOINTS U-joints are crosses between two Y-shaped yokes. Because U-joints transfer power at an angle they DO NOT rotate at a constant velocity nor are they vibration free.

SPEED VARIATIONS Input and output speeds are the same. But the drive shaft itself speeds up and slows down every 90 degrees.

PHASING of U - JOINTS To provide for this canceling effect, drive shafts should have at least two U-joints and their angles must be slight and equal to each other. Speed fluctuations can be canceled if the driven yoke has the same point of rotation, or same plane , as the driving yoke.

CANCELING ANGLES Vibrations can be reduced by canceling angles.

TYPES of U - JOINTS Single universal joint retained by either an inside or outside snap ring. Spicer - outside snap ring Mechanics or Detroit - inside snap ring Universal joints held in the yoke by U-bolts or lock plates.

DOUBLE CARDAN Coupled Universal Joint Total operating angle is divided equally between the two joints. Because the two joints operate at the same angle, fluctuations are canceled out. Double Cardan is classified as a constant velocity joint.

MAINTENANCE Factory joints do not have grease fittings. Replacement joints need servicing. Dirt and other buildup on the shaft will affect its balance.

BIBLIOGRAPHY: www. Careernet.com Step 1 Chasis and Power Train, Toyota Astra Motor Step 2 Chasis and Power Train, Toyota Astra Motor

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