Ch. 77 POWERPOINT

Use the textbook to define these Technical Terms:

1. center link

2. collapsible steering column

3. flexible coupling

4. idler arm

5. gearbox housing

6. parallelogram steering linkage

7. pitman arm

8. rack-and-pinion steering

9. power steering pump

10. power steering

11. steering column assembly

12. tie-rods

13. universal joint

Use the textbook to answer these discussion questions:

1. Identify the major parts of a steering system.

2. Compare the differences between a linkage steering and a rack-and-pinion steering system.

Read the chapter summary below:

Summary

■ The steering system is vital to the safety of an automobile. It allows the driver to safely maneuver the vehicle.

■ There are two basic kinds of steering systems in use today: linkage (worm gear) steering systems and rack-and-pinion steering systems.

■ The steering column assembly consists of the steering wheel, steering shaft, steering column (outer housing), and, sometimes, ignition key mechanism, a flexible coupling, and a universal joint.

■ To help prevent theft, late-model vehicles also have a locking steering wheel.

■ Most vehicles use a collapsible steering column to help prevent driver chest and face injury during an auto accident.

■ A tilt steering column has a flex joint, or U-joint, that allows the top half of the column and the steering wheel to be positioned at different angles or heights.

■ The recirculating-ball gearbox is normally used with a linkage steering system on large trucks.

■ Gearbox ratio, or steering gear reduction, is basically a comparison between steering wheel rotation and sector shaft rotation.

■ The steering linkage is a series of arms, rods, and ball sockets that connects the steering gearbox to the steering knuckles.

■ Ball sockets provide for motion in all directions between two connected parts.

■ A manual rack-and-pinion steering gear basically consists of a pinion shaft, a rack, thrust spring, bearings, seals, dust boots, tie-rods, and a gear housing.

■ Tie-rod assemblies for rack-and-pinion steering connect the ends of the rack with the steering knuckles.

■ Power steering systems normally use an engine- driven pump and a hydraulic system to assist steering action. They can also use an electric motor in the rack or inside the steering wheel to provide power assist.

■ A power cylinder for rack-and-pinion steering is a precisely machined tube that accepts the power piston.

■ Proportional rack-and-pinion power steering senses vehicle speed and steering load to ensure adequate road feel at the steering wheel.

■ In a four-wheel steering system, all four wheels change direction to improve handling, stability, feel, and maneuverability.