# DRIVE SHAFTS and UNIVERSAL JOINTS

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DRIVE SHAFTS and UNIVERSAL JOINTS
CBC AUTOMOTIVE RK DRIVE SHAFTS and UNIVERSAL JOINTS Chapter 6 Page 119 Classroom Manual

OBJECTIVES CBC AUTOMOTIVE RK 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.
CBC AUTOMOTIVE RK 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
CBC AUTOMOTIVE RK Typical universal joint and yokes.

DRIVE SHAFT CONSTRUCTION
Page 121 DRIVE SHAFT CONSTRUCTION CBC AUTOMOTIVE RK 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 CBC AUTOMOTIVE RK

Types of Drive Shafts Hotchkiss - External shaft and U-joints.
Page 122 Types of Drive Shafts CBC AUTOMOTIVE RK 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.
Page 124 UNIVERSAL JOINTS CBC AUTOMOTIVE RK 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.

CBC AUTOMOTIVE RK

SPEED VARIATIONS Input and output speeds are the same.
Page 125 SPEED VARIATIONS CBC AUTOMOTIVE RK Input and output speeds are the same. But the drive shaft itself speeds up and slows down every 90 degrees.

Page 127 PHASING of U - JOINTS CBC AUTOMOTIVE RK 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.
Page 128 CANCELING ANGLES CBC AUTOMOTIVE RK Vibrations can be reduced by canceling angles.

Page 128 TYPES of U - JOINTS CBC AUTOMOTIVE RK 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. CBC AUTOMOTIVE RK

DOUBLE CARDAN Coupled Universal Joint
Page 130 DOUBLE CARDAN Coupled Universal Joint CBC AUTOMOTIVE RK 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.
Page 132 MAINTENANCE CBC AUTOMOTIVE RK Factory joints do not have grease fittings. Replacement joints need servicing. Dirt and other buildup on the shaft will affect its balance.