Chapter 8

Question 1

List the components of a typical drum brake assembly.

Answer 1

drum, hub, brake shoes, backing plate, hydraulic wheel cylinder, springs, parking brake

Question 2

Describe the function of a wheel cylinder.

Answer 2

converts hydraulic pressure to mechanical force

Question 3

Describe brake gas fade.

Answer 3

hot gases get trapped under the shoes and acts as a lubricant

Question 4

What are the major advantages to using drum brakes?

Answer 4

self energizing & servo action

Question 5

Since duo-servo brakes supply more braking force than leading-trailing drum brakes, why would engineers use the leading-trailing design?

Answer 5

if duo-servo brakes are used in the rear wheels then the could overpower them and cause the back brakes to lock up

Question 6

What determines the braking surface area of a drum brake?

Question 7

What is the function of a self-adjuster?

Answer 7

use the movement of brake shoes to maintain proper clearance

Question 8

What is a self-energizing brake?

Answer 8

creates its own mechanical leverage

Question 9

What is the difference between the braking action of leading-trailing and duo-servo brakes?

Answer 9

A duo-servo brake is distinguished from a leading-trailing brake by a single anchor post at the top of the backing plate. The top of each shoe web has a semicircular notch, and the return springs hold the notches tightly against the anchor post.

Question 10

How are the brake shoes returned to their released position when the brake pedal is released?

Answer 10

The mechanical servo returns the brake shoes

Question 11

________ are the components that mount the friction material or linings that contact the drums.

Answer 11

brake shoes

Question 12

The hydraulic and friction components are attached to the _______

Answer 12

backing plate

Question 13

_________ operation is the action of a drum brake shoe when drum rotation increases the application force of the shoe by wedging it tightly against the drum.

Answer 13

self-energizing

Question 14

The ________ is usually part of the parking brake strut that is mounted between the two shoes of leading-trailing brakes.

Answer 14

star wheel

Question 15

A duo-servo brake is distinguished from a leading-trailing brake by a single anchor post at the _______ of the backing plate.

Answer 15

top

Question 16

_________ brakes, also called partial-servo or non-servo brakes.

Question 17

Duo-servo brakes commonly have self-adjusters operated by the ________ shoe.

Answer 17

secondary

Question 18

Cam-type adjusters use cams with an ________ pin that fits in a slot on the shoes.

Answer 18

adjuster

Question 19

Wheel cylinders convert _________ pressure from the master cylinder to ________ force that applies the brake shoes.

Answer 19

hydraulic, mechanical

Question 20

The forward shoe of a duo-servo brake is called the ________ shoe.

Answer 20

primary

Question 21

Technician A says that for the same brake pedal force, duo-servo brakes apply a greater braking force than leading-trailing-shoe brakes.

Technician B says that the servo action of the duo-servo brakes takes place only when the car is moving forward.

Who is correct?

Answer 21

a

Question 22

Technician A says that the leading shoe lining receives the greatest wear on a leading-trailing shoe brake.

Technician B says that leading-trailing brakes are non-servo brakes.

Who is correct?

Answer 22

c

Question 23

Technician A says that some leading-trailing-shoe brakes with an adjustable parking brake self-adjust when the service brakes are applied.

Technician B says that some brakes with an adjustable parking brake strut self-adjust when the parking brake is applied.

Who is correct?

Answer 23

b

Question 24

Technician A says that on a duo-servo brake, the force applied by the drum to the primary shoe aids the force applied by the wheel cylinder.

Technician B says that on a leading-trailing brake, the force applied by the drum to the primary shoe opposes the force applied by the wheel cylinder.

Who is correct?

Answer 24

a

Question 25

Two technicians are discussing automatic brake adjusters.

Technician A says that self-adjusting brakes were first used in 1947 by Studebaker.

Technician B says that self-adjusting brakes were used on all domestic drum brakes in 1963.

Who is correct?

Answer 25

c

Question 26

Technician A says that rear brake drums are usually separate assemblies from the rear hubs.

Technician B says that Tinnerman nuts at the wheel studs hold the drum onto many rear hubs.

Who is correct?

Question 27

While discussing a typical leading-trailing brake installation,

Technician A says the wheel cylinder is mounted at the top of the backing plate, and the cylinder pushrod or shoe links bear against the upper ends of the shoe webs.

Technician B says the lower end of each shoe bears against, or is held onto, an anchor block or anchor post toward the bottom of the backing plate.

Who is correct?

Question 28

Technician A says that most self-adjusters are the same for both sides of the vehicle.

Technician B says that some technicians service one side of the vehicle at a time and use the other side as a reference while assembling drum brake assemblies.

Who is correct?

Answer 28

b

Question 29

Technician A says on leading-trailing brakes, the lining on the leading and trailing shoes are usually the same length and positioned in the same location on each shoe.

Technician B says on duo-servo brake, however, the primary shoe lining is shorter than the secondary lining and may even have a different coefficient of friction.

Who is correct?

Answer 29

d