Q2. What term is used to refer to the comparison of front-wheel to rear-wheel braking effort?

Q3. Typically, what percentage of the braking does the rear brake handle?

Q4. What component of a hydraulic brake system coverts the force of an operator's foot into hydraulic pressure?

Q5. In a vehicle using a dual master cylinder, what type of system operates the brake assemblies on opposite corners?

Q6. What component in a hydraulic brake system is used where a single brake line feeds two wheel cylinders?

Q7. What type of self-adjusting system uses braided steel cable?

Q8. Disc brakes use servo actions. (T/F)

Q9. What are the three types of brake shoes?

Q10. What component of a disc brake system is a nonrotating unit?

Q11. Why is a metering valve used?

Q12. Describe a combination valve.

Q13. What component of an ABS system uses a wheel speed sensor signal to operate the hydraulic actuator?

Q14. What component of an ABS system is mounted on each spindle or hub?

Q15. A hydroboostpower brake system uses pressure from the power steering pump. (T/F)

Q16. What are the three brake pedal application distances?

Q17. At what thickness should disc brake pads be replaced?

Q18. What action should be taken before installing a new master cylinder on a vehicle?

Q19. What device is used to measure brake drum diameter?

Q20. The amount of side-to-side movement of a brake disc is known by what term?

Q21. How much metal is to be removed when resurfacing a brake disc?

Q22. When pressure bleeding a brake system, what is the charging pressure of the bleeder ball?

AIR BRAKE SYSTEM

Learning Objective: Describe the operation, terms, and component functions of an air brake system. Describe the procedures for servicing an air brake system.

Unlike liquids, gases are compressed easily. If a gas, such as air, is contained and a force applied to it, it is compressed and has less volume. Placing a weight on a piston that fits in the container can exert such a force. The air that originally filled the entire container is pressed into only a portion of the container due to the force of the weight upon it. The pressure of the compressed air, resulting from the force exerted upon it by the weight, will be distributed equally in all directions just as it is in a liquid.

An air brake system performs the following basic actions:

An air pump or compressor driven by the engine is used to compress air and force it into a reservoir where it is forced under pressure and made available for operating the brakes.

Air under pressure in the reservoir is released to the brake lines by an air valve operated by the brake pedal.

This released air goes to brake chambers (located at each wheel) that contains a flexible diaphragm. Against this diaphragm is a plate that is connected directly to the mechanism on the wheel brakes by linkage.

The force of the compressed air admitted to the brake chamber causes the diaphragm to move the plate and operate the brake shoes through the linkage.

Considerable force is available for braking because the operating pressure may be as high as 110 psi. All brakes on a vehicle, and on a trailer when one is used, are operated together by means of special regulating valves. A diagram of a typical air brake system is shown in figure 7-39.

COMPRESSOR, GOVERNOR, AND UNLOADER ASSEMBLY

The COMPRESSOR is driven from the engine crankshaft or one of the auxiliary shafts. The three common methods of driving the compressor from the engine are gear, belt, and chain. The compressor may be lubricated from the engine crankcase or self-lubricating. Cooling may be either by air or liquid