Ch. 5
Why would you not want to use air or a brush to clean your brake pad or brake shoe?
Because that dust is dangerous and can also contain asbestos
Where can brake dust be found?
Brake shoe and brake pad
the ___________ _____________ help to keep the fluid from escaping around the forward moving pistons
Cup Seals
Make sure the color is clear or light amber for which types of DOT brake fluid?
DOT 3 , 4 or 5.1
Which type of brake fluid is used on most domestic vehicles?
DOT3
How do you find pressure?
Force divided by area
How do you find area?
Force divided by pressure
If the brake fluid is low what should you check?
Look for leaks, worn brake pads and or shoes.
How does the leading/ Trailing drum brake work?
These shoes act independently of each other
True or false? Hydraulic systems are simple to control and don't make much noise
True
The type of brake system will determine the type of _______ _______________
brake fluid
With disc brakes, what parts are experiencing friction?
Between the pads and rotors
What does the F, the P, and the A stand for in F=PA?
F = force, P= pressure, and A = area
What would you check the wheel cylinder for on a drum brake?
You want to make sure that sucker isn't leaking
Transfers force from the primary shoe to the secondary shoe
adjusting screw
What can cause brake fade?
constant high temperatures
You should what if you replace one brake pad?
replace all of them and lube up the caliper slides up
Where does the fluid go when the master cylinder pistons and seals retract to the fully released position?
the fluid returns to the reservoir
Used in vehicles with larger underhood space. concerning boosters
vacuum booster
Applies the brake shoe by converting the hydraulic pressure in the system to mechanical force
wheel cylinder
On a floating caliper how does it differ from a fixed caliper?
A floating caliper has the pad on the inboard side against the piston. and on a fixed caliper the squeezing or clamping force just comes from both sides.
What does the brake balance control system include?
A metering valve which controls timing, a proportioning valve which helps control the pressure in the rear brakes, and a sometimes a combination valve is used which does the job of both the metering and proportioning valve.
Big ass trucks use what type of brakes?
Air brakes
What does the connecting spring do on drum brakes?
Attaches to the primary and secondary shoe and pulls the shoes together against the adjusting screw
Apart from fluid change intervals, the hydraulic system doesn't need regular service. Why is that?
Because it is a closed system
Technician A says the area of the pistons in the brake calipers and wheel cylinders directly relates to the force that is applied to the brake system. Technician B says the pressure in the hydraulic lines increases when pressure is applied to the brake pedal. Which technician is correct?
Both?
What type of hydraulic system do most cars use.
Diagonally split hydraulic system
What are the standard for brakes today?
Disc brakes
What are the advantages of disc brakes?
Doesn't pull as much, is fade resistant, doesn't need to be adjusted (is self adjusting). It's also the more efficient braking system
What is important to remember about the brake fluid DOT3
Don't store for more than a week, and this stuff will ruin rubber seals
What are the two types of drum brakes?
Dui-servo and Leading/Trailing
The area of the brake pedal determines the pressure applied to the brakes.
False
True or False? Air brakes don't need regular service
False. They can get contaminants in the system when attaching trailers or something.
What are the two types of calipers for disc brakes?
Fixed Caliper and floating Caliper
The _________ between two masses converts kinetic energy to thermal energy
Friction
Because of weight transfer and weight bias, the ________ must provide the bulk of the braking power for both passenger vehicles and trucks.
Front brakes
The older version of a dual hydraulic circuit that is typically used in rear wheel drive vehicles?
Front to rear hydraulic system
What is the brake adjuster assemblies job?
Helps correct clearance between brake shoe lining and drum, also transfers braking force from the primary shoe to the secondary shoe.
What do the retaining springs do on the shoe brake?
Holds the brake shoes to the backing plate, and helps reduce noise
Also called a hydro-boost unit
Hydraulic booster
What are the two types of power boosters?
Hydraulic booster and vacuum booster
What main two brake systems are there? And what do most vehicles incorporate to help with braking?
Hydraulic brakes and air brakes. Also antilock brake system known as ABS is added
What does the two separate pressurized compartments help with concerning the master cylinder?
If one circuit is leaking or damaged it allows the car to still have braking power
When would you want to replace the drum brake?
If there's too much scoring or if it's cracked. Also if the diameter is out of specs you'd want to fix that.
DOT 4 brake fluid. What should you know about it?
It absorbs less moisture than DOT3 giving it a higher boiling temperature point. probably gonna find this stuff in higher performance stuff because of that point.
What does the wheel cylinder do on a drum brake?
It fill with hydraulic fluid and engages the brake lining with drum surface
DOT 5.1 what should you know?
It has the same performance as DOT5 but doesn't leave a spongy feel in the brake system.
Where is the rotor located and how does it work?
It is mounted on the wheel hub and provides the braking surface for the pads
is the energy of an object in motion
Kinetic energy
What would you want to check on the brake shoe on a drum brake?
Look for cracks and too much wear. Also look for loose rivets. Make sure the shoe sizes are the same as the original. Also make sure that they're facing the same way
How do you measure pressure?
Pounds of force, or PSI
What type of system uses a power brake booster?
Power assist system
There are two shoes on the drum brake system, what are they called?
Primary shoe and secondary shoe. The primary shoe is the first shoe to come into contact with the drum, but the secondary shoe is doing most of the stopping
What would you check the backing plate on a drum brake for?
Replace if it's seized or worn and damaged.
The loss of stopping _________ is known as brake fade.
Stopping force
What can expand or contract and creates a seal that keeps the brake fluid in and prevents moisture and contamination from getting in ?
The Reservoir Diaphragm on the master cylinder
Friction occurs in two major areas of the vehicle. What are they
The braking components, and the tires with the road.
Where does the vacuum booster get the vacuum suction from?
The pressure comes from the difference between engine vacuum and atmospheric pressure
What are the disadvantages of disc brakes?
There's no self-energizing servo action, and has loud squeaks and noises
How does an air brake differ from a hydraulic system?
They just use air the same way a hydraulic system uses fluid. It just does it with air.
what do calipers do on disc brakes?
They push the pads against the rotor
What does the hydraulic system include and what does it do?
This delivers pressurize fluid to each wheel for braking. It included the brake components and hydraulic lines and hoses
What does the assist system or boost system do?
This helps increase the brake pedal force. It does this with a vacuum or hydraulic assist.
What is the return springs function on a drum brake?
This holds the brake shoes away from the drum until brakes are applied
What does the brake stop lamp system do?
This is the switch that is activated when you push the brake pedal down activating the rear lights
What does the anti lock system or ABS do?
This monitors wheel speed, brake pedal movement, and brake pressure to allow the vehicle to stop quickly. This system allows the driver to maintain control and prevent wheel lock up when braking. It does this by pulsating the brake something like twenty times per second when needed to help maintain control.
What hydraulic system helps resist front brake pull if one circuit fails, and can be found in some dual piston calipers?
Triangle split hydraulic system
True of False? Force is found by multiplying pressure by area?
True
True or False? Many brake systems use hydraulic assist to help slow and stop the vehicle.
True
True or False? Pressure is found by multiplying area by force
True
The tendency for vehicles to carry the bulk of weight in the front.
Weight bias
A shift of weight from the rear to the front of a vehicle during braking.
Weight transfer
What does pascals law state?
When force is applied to a liquid confined in a container or an enclosure, the pressure is transmitted equally and undiminished in every direction.
How does a duo-servo drum brake work?
When you apply the brake the drum brake is rotating and pulls up on the primary shoe which in turn moves the secondary shoe
How is pressure in a brake system work?
When you push on the brake pedal, the brake pedal pushes on the master cylinder piston which creates the pressure that is applied to the brake fluid in order to move a caliper or wheel cylinder piston.
What would be an advantage of using drum brakes?
You can incorporate a simple parking mechanism into them, they have a lower noise level and they're self energizing
If you attach a trailer to larger truck like a sixteen wheeler or dump truck type truck and then you attach a trailer with air brakes what do you need to do before it is functional?
You need to pressurize the system on the trailer first
What should you look for in the parking brake on a drum brake for?
You want it to be able to move freely
What would you check the adjusting screw for on drum brakes?
You want to make sure it can move freely and replace it if it's seized up. Also you want to check to see if the corrosion is too bad or if it's too badly stripped.
How is a parking brake typically applied?
a foot pedal or by pulling a brake lever.
What connects the cylinder to the brake pedal ?
a pushrod and brake booster
What do you use to check moisture in the brake fluid? And what else might you want to check for?
a test strip. You'd also want to check for copper in the system
What do metering valves do to help with braking
allows the front and rear brakes to operate at the same time
Locates shoes on the backing plate
anchor pin
The _______ prevents the shoes from rotating with the drum
anchor pin
When the brake pedal is _____________ the air valve closes the rear chamber's vacuum port and opens the atmospheric port.
applied
Brake fluid expands and contracts with changes in temperature.
applied position
Which system incorporates mechanical elements that activate the hydraulic brake system?
apply system
Master cylinder pistons and seals retract to the fully released position again
at rest position
Why should you not use brake fluid from a container that has been left open
because exposure to air can get moisture mixed into the fluid
Why do we use a dual Hydraulic circuit instead of the older single hydraulic circuit?
because it's safer, and you don't lose as much pressure
Where is the brake pads located?
between the rotor and caliper
With drum brakes, what parts are experiencing friction?
between the shoe linings and drums
Pressure increases throughout the hydraulic system when the passages between the reservoir and the hydraulic circuits ________
close
Holds primary and secondary shoes against the adjuster
connecting spring
What does the proportioning valve do?
controls pressure to the rear wheels. Also helps improve control during abrupt stops
What would I check a brake line for in a drum brake?
cracks, leaks, too much contamination or too much wear.
Check the caliper for
damage, corrosion or leaks around the piston seals, also ensure that it moves smoothly
Calipers on a ____________ caliper forces the pistons on both sides of the rotor to apply the brake pads
fixed
A ___________ caliper has one or more pistons on the inboard side
floating
pressure multiplied by area equals ___________
force
Resistance to movement between two masses in contact with each other
friction
The type of booster that uses power steering pump pressure
hydraulic booster
Which way should the primary shoe be facing on drum brake system?
it should be facing the front of the vehicle
Where is the parking brake cable is attached to on a drum brake set up?
it's attached to the rear brakes
What would some disadvantages of drum brakes be?
less fade resistant, tendency to pull and grab, poor heat dissipation and they require special linkage for self adjustement.
Is it okay to use brake fluid that has been opened already?
no
Contacts the drum first during forward braking
primary shoe
DOT 5 Brake fluid. What should you know?
purple in color, and does not damage interior or exterior car finishes. This type of brake fluid attracts and retains more air than other brake fluids and you'll have to use a power flush to get rid of bubbles. Remember air in your system means a spongy brake feel
The brake pedal is attached to the ________________ which then pushes pressurized fluid to the _____________ pressure area and then the _____________ pressure area
pushrod. Primary. Secondary
Brake fluid from the hydraulic circuit returns to the reservoir in the what position?
released
Holds brake shoes away from drum until brakes are applied
return spring
Since the rotor is what the brake pads are coming contact with what should you check the rotors for?
scoring and thickness variation
When the pistons move forward, the ports between the reservoir and the hydraulic circuits __________
seal
Energized by the adjusting screw during forward braking
secondary shoe
Area is measured in?
square inches
Are Hydraulic lines stationary or flexible?
stationary
What is brake fade?
the loss of stopping force due to loss of friction
What are the three parts of the primary shoe?
the web, the table and lining
Is the energy that increases as its temperature increases
thermal energy
What does the apply system do and what does it include?
this includes all levers and pedals that activate the braking system. it transfers motion and force to the brake fluid by pressurizing the brake fluid.
What would you check the springs on a drum brake for?
too much stretching, or if they're too collapsed. Or damaged ends
Where does fluid exit through once fluid is forced through the master cylinder?
two Master cylinder ports. Once the fluid exits it goes separate ways sending fluid to the front brakes and the rear brakes
