Chapter 75 POWERPOINT

Use the textbook to define these Technical Terms:

1. active suspension system

2. automatic suspension leveling systems

3. ball joints

4. control arm

5. control arm bushings

6. curb height

7. dead axle

8. independent suspension

9. jounce bumpers

10. nonindependent suspension

11. shock absorber

12. strut assembly

13. sway bar

14. torsion bar suspension

Use the textbook to answer these discussion questions:

1. Compare the various types of suspension systems.

Read the chapter summary below:

Summary

■ The suspension system allows the tires and wheels to move up and down over bumps and holes in the road surface.

■ Chassis stiffness is a primary factor affecting how quiet and smooth a vehicle drives—the stiffer the chassis, the better.

■ Independent suspension allows one wheel to move up and down with little effect on the other wheels.

■ Nonindependent suspension has both the right and left wheels attached to the same solid axle.

■ Lateral acceleration is the amount of side force a vehicle can handle in a sharp turn or curve before its tires lose traction and skid.

■ Suspension system springs must jounce (com- press) and rebound (extend) with bumps and holes in the road surface.

■ A control arm holds the steering knuckle, bearing support, or axle housing in position as the wheel moves up and down.

■ A strut rod fastens to the outer end of the lower control arm and to the frame. It keeps the control arm from swinging toward the rear or front of the vehicle.

■ Ball joints (short for ball-and-socket joints) are connections that allow limited rotation in every direction.

■ Shock absorbers limit spring oscillations (com- pression-extension movements) to smooth the vehicle’s ride.

■ A strut assembly consists of a shock absorber, a coil spring (most types), and an upper damper unit.

■ A sway bar, also called stabilizer bar, is used to keep the body from leaning excessively in sharp turns.

■ Jounce bumpers are blocks of hard rubber that keep the suspension system parts from hitting the frame or body when the vehicle hits large bumps or holes.

■ A long-short arm suspension uses control arms of different lengths to keep the tires from tilting with suspension action.

■ A MacPherson strut suspension uses only one control arm and a strut assembly (spring, damper, and shock absorber unit) to support each wheel assembly.

■ A dead axle is a term used to describe a solid rear axle on a front-wheel-drive vehicle.

■ A suspension leveling system is used to maintain a constant vehicle attitude (height ratio between front and rear of body) as the amount or distribu- tion of weight in the vehicle changes.

■ To maintain correct ride height, an electronic height control system uses height sensors and an ECM to control the operation of a small electric air compressor.

■ An electronic shock absorber system uses various vehicle sensors, an electronic control module, and shock absorber actuators to control ride stiffness.

■ An active suspension system uses computer- controlled hydraulic rams instead of conventional suspension system springs and shock absorbers.