DRIVE SHAFTS and UNIVERSAL JOINTS

1
DRIVE SHAFTSand UNIVERSAL JOINTS
CBC AUTOMOTIVE RK

• Chapter 6
• Page 119
• Classroom Manual

2
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.

3
INTRODUCTION
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.

4
DRIVE SHAFT CONSTRUCTION
CBC AUTOMOTIVE RK

• Typical universal joint and yokes.

5
DRIVE SHAFT CONSTRUCTION
Page 121
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.

6
MOVEMENT
CBC AUTOMOTIVE RK
7
Types of Drive Shafts
Page 122
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.

8
UNIVERSAL JOINTS
Page 124
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.

9
CBC AUTOMOTIVE RK
10
SPEED VARIATIONS
Page 125
CBC AUTOMOTIVE RK

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

11
PHASING of U - JOINTS
Page 127
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.

12
CANCELING ANGLES
Page 128
CBC AUTOMOTIVE RK

• Vibrations can be reduced by canceling angles.

13
TYPES of U - JOINTS
Page 128
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
14
DOUBLE CARDAN Coupled Universal Joint
Page 130
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.

15
MAINTENANCE
Page 132
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.