Brake Systems Flashcards
What are the major parts of a typical automotive braking system?
- brake pedal
- brake booster
- master cylinder
- brake lines
What is the purpose of any automotive braking system?
To allow control, to stop, and to hold vehicle.
Describe the brake fluid viscosity.
At temperatures of -40 and below the brake fluid must still flow freely
Describe the brake fluid boiling point.
The brake fluid must be able to handle extreme heat (temps up to 200C) without boiling.
What happens if brake fluid boils?
The fluid will compress and brakes will become spongy and inefficient.
Describe non-corrosive in brake fluid, in the brake system.
The fluid must not corrode with any metals, slight corrosion can cause the tiny parts of a braking system to move freely.
what metals can the brake system include?
Aluminum, brass, steel, and cast iron
Describe the hydroscopicity in brake fluid.
The ability to absorb moisture in the braking system so it does not corrode metal parts of the braking system.
What happens to the boiling point of brake fluid when it absorbs more moisture?
Boiling point goes down
Describe the lubrication in brake fluid.
Brake fluid must provide all the lubrication the system requires.
Why can’t you use a mineral based lubricants in a braking system?
Mineral based lubricants would cause the rubber seals to sweep excessively.
Describe the stability in brake fluid.
The brake fluid must be able to come into contact with various metals, handle extreme pressure and heat, and not break down.
Describe the miscibility of brake fluid.
Brake fluids of the same rating must be able to mix with brake fluid from other manufacturers without reaction.
Describe the rubber compatibility in brake fluid.
Brake fluid is designed to not react with the rubber inside a brake system.
What are the cautions with brake fluid?
Brake fluid can damage rubber and paint outside the braking system.
What’s are the 3 types of brake fluid?
Dot3, dot4, and dot 5
What brake fluid(s) are glycol based fluid?
Dot 3 and dot 4
What brake fluid(s) are silicone based fluid?
Dot 5
Dot ___ and Dot___ are compatible. Dot _____ is never compatible.
Dot3 and dot 4, dot 5
What is the colour of dot 3, dot 4, and dot 5 brake fluid?
Dot 3 and dot 4 are amber coloured, dot 5 is purple
What is the dry boiling point for dot 3?
205 degree C
What is the dry boiling point for dot 4?
230 degree C
What is the dry boiling point for dot 5?
260 degree C
What is the boiling point with 3% water for dot 3?
140 degree C
What is the boiling point with 3% water for dot 4?
155 degree C
What is the boiling point with 3% water for dot 5?
180 degree C
Which fluid does not absorb water, and shouldn’t be used in braking systems with ABS?
Dot 5
What is the brake master cylinder?
Is basically a foot operated pump
What are the main functions of a master cylinder?
- To develop and equalize pressure for the brake system
- Maintain appropriate fluid level
- keeps out contaminants(by keeping a slight positive pressure on the system)
What is a tandem master cylinder?
It splits the brake system into 2 separate circuits with equal pressure.
The brake system can be split in 2 ways, what are they?
Diagonally split system, or longitudinally.
How are the brake lines connected in a diagonally split brake system?
Left front with the rear right, and the right front with the left rear.
How are the brake lines connected in a longitudinally split brake system?
Front to rear, the fronts connect and then the rear connect together.
What are the 2 types of brake sensors?
A fluid level warning sensor, a brake light sensor/switch is usually found on the brake pedal assembly
Describe power brakes.
Assist in braking when the pedal is depressed
Describe a hydraulic brake booster.
Hydraulic pressure is applied by the power steering pump
Describe the vacuum booster.
Works with vacuum generated by the engine
Describe the electric booster.
Uses an electric motor to generate additional pressure
Describe a metering valve.
to slightly delay the application of the front brakes. Equalizes brake action at each wheel
Describe the proportioning valve.
Provide balanced braking during sudden, hard braking by restricting fluid pressure to the rear brakes.
What brake system is a metering valve used in?
Used in line with front disc and rear drum brake systems, with a longitudinally split master cylinder.
What brake system is a proportioning valve used in?
In vehicles with front disc, rear drum brake systems.
Describe a combination valve.
Incorporates a metering valve, a proportioning valve and a pressure differential warning switch all into one assembly
What is the most common configurations for drum brake shoes?
Are duel servo and leading/trailing
Describe servo action.
Refers to one brake shoe being used to apply the other shoe
Describe duel servo.
Simply means that servo action occurs in both froward and reverse. The rear shoe will energize first and is responsible for a higher amount of the braking force.
In dual servo drum configurations the _____ shoe is usually _______ than the ______ shoe.
Rear shoe, larger, front shoe
Describe a leading/trailing system.
Front shoe will energize when moving forward and the rear shoe will energize while moving backwards. This system requires more force, less prone to locking up.
What are some disadvantages in the disc brake assembly?
More effort is required to apply disc brakes because that are not self energizing
Disc brakes are more prone to cause noise
What are the advantages of disc brake assembly?
- uses less parts
- dissipate heat better
- less prone to brake fade
- self clean
- self adjust
- force is applied more rapidly and evenly
Describe a fixed brake caliber.
The entire caliber is solidly mounted and there is a piston or pistons on both sides of the disc.
Describe a floating brake caliber.
A caliber bracket is solidly mounted and the caliber itself within that bracket isn’t solidly mounted, it can slide.
What are the 3 main types of park brake assemblies?
Drum brake, disc brake, drum in hat.
Describe the drum brake type parking brake assembly.
Rear drum brake assembly used to hold vehicle stationary. Is a cable or linkage attracted to a park brake lever which, when applied holds the shoes tightly against the drum.
Describe the disc brake type of parking brake assembly.
Rear disc assemblies used to hold vehicle stationary. Is a cable or electric motor attached directly to the brake caliber. When applied the inner brake pad is pressed firmly against the rotor.
Describe the drum in hat type of parking brake assembly.
Uses a combination of rear disc brakes for stopping the vehicle, and a separate drum brake system for the parking brake.
What is the minimum thickness of riveted brake pads?
1.5mm to rivets
What is the minimum thickness of non riveted brake pads?
3mm to pad body
What is the minimum thickness on riveted brake shoes?
1mm to rivets
What is the minimum thickness of non riveted brake shoes?
1.5mm to shoe body
What controls a ABS system?
Wheel speed sensors, an ABS computer
A brake service is usually recommended very_______kms?
32,000kms
What does a disc brake service usually include?
- removing brake pads contact points
- lubricating contact points
- remove and dust/lip from rotors
- hand sand friction surface of rotor
- sand friction surface of brake pads
- clean and lub calliper slide pins
- adjust park brake shoes if applicable (drum in hat style)
What does a drum brake service usually include?
- cleaning brake dust
- lub contact points for shoes
- sand friction surfaces on brake shoes
- remove any rust/lip on brake drums
- sand friction surface of brake drum
- adjust brake shoes
