What is the most What is the most ImportantImportant system system on your vehicle? on your vehicle?

(The Brake (The Brake

System)System)

VocabularyVocabulary

1.1. Hydraulics 10.Metering valveHydraulics 10.Metering valve

2.2. Pascal’s laws 11.Brake warning lightPascal’s laws 11.Brake warning light

3.3. Brake fluid 12.Brake line with double flare Brake fluid 12.Brake line with double flare

4.4. Master cylinder 13.Pads and shoesMaster cylinder 13.Pads and shoes

5.5. Wheel cylinder 14.ABS(anti- lock brake system)Wheel cylinder 14.ABS(anti- lock brake system)

6.6. Caliper 15.BleedingCaliper 15.Bleeding

7.7. Disk brake rotor 16.Star wheel adjusterDisk brake rotor 16.Star wheel adjuster

8.8. DrumDrum

9.9. Proportioning valveProportioning valve

Kinetic EnergyKinetic Energy

Your vehicles brake system converts Your vehicles brake system converts kinetic energy ( energy in motion) to kinetic energy ( energy in motion) to thermal energy (Heat energy) using thermal energy (Heat energy) using friction. It takes a lot of friction to friction. It takes a lot of friction to stop a 4000 lbs car going 60 MPH ! stop a 4000 lbs car going 60 MPH !

Friction causes heat – lots of it!Friction causes heat – lots of it! Modern cars use hydraulics to Modern cars use hydraulics to

create the force needed to make create the force needed to make friction and stop the vehicle.friction and stop the vehicle.

FrictionFriction Created when one Created when one

surface rubs on surface rubs on another.another.

The larger the brake The larger the brake pad or shoe the more pad or shoe the more potential friction.potential friction.

The larger the brake The larger the brake rotor or drum the more rotor or drum the more potential friction. potential friction.

The friction will change The friction will change as the force applied as the force applied changes.changes.

Drum and Disk functionDrum and Disk function

Pascal’s LawPascal’s Law

Pascal’s law is the law of hydraulics.Pascal’s law is the law of hydraulics. Pascal’s law states “ a pressure Pascal’s law states “ a pressure

applied to a confined fluid is applied to a confined fluid is transmitted undiminished to every transmitted undiminished to every portion of the surface of the portion of the surface of the containing vessel”. containing vessel”.

The Hydraulic system is used to The Hydraulic system is used to apply the friction material and stop apply the friction material and stop the car. the car.

Typical 4 wheel basic hydraulic system

Typical Brake systemTypical Brake system

PART 2PART 2Brake system partsBrake system parts

Master CylinderMaster Cylinder

Generates the Generates the pressure needed in pressure needed in the brake system.the brake system.

The harder you The harder you push the pedal the push the pedal the more pressure the more pressure the master cylinder master cylinder makes.makes.

Keep cyl above Keep cyl above Min level Min level

Drum Brake AssemblyDrum Brake Assembly

A cast iron brake A cast iron brake drum is attached to drum is attached to the axle of the the axle of the vehicle and rotates vehicle and rotates with the wheel.with the wheel.

The drum wears The drum wears over time and can over time and can be machined be machined approx .060 larger approx .060 larger inside from its inside from its original size.original size.

Drum brake – backing plate Drum brake – backing plate assemblyassembly

Wheel cylinder

Drum brake – Backing plate Drum brake – Backing plate assemblyassembly

Wheel cylinderWheel cylinder

Receives hydraulic pressure from Receives hydraulic pressure from master cylinder.master cylinder.

Applies pressure to the brake shoes.Applies pressure to the brake shoes. Has two pistons, piston cups, dust Has two pistons, piston cups, dust

boots, and one spring inside the boots, and one spring inside the body of the wheel cyl.body of the wheel cyl.

Wheel cylinder assemblyWheel cylinder assembly

Brake shoesBrake shoes Used on a drum brake.Used on a drum brake. Steel backing with Steel backing with

some type of some type of composite friction composite friction material.material.

Riveted and bonded Riveted and bonded types.types.

Primary shoe goes Primary shoe goes towards the front , towards the front , secondary to back. secondary to back.

Never breath brake Never breath brake dust.dust.

Disk Brake AssemblyDisk Brake Assembly

Brake rotorsBrake rotors Typically made of Typically made of

cast iron.cast iron. Can be vented or Can be vented or

non-vented.non-vented. Will wear or warp Will wear or warp

over time or with over time or with abuse.abuse.

Can be machined Can be machined approx .060 before approx .060 before replacement is replacement is mandatory.mandatory.

Rotates with axleRotates with axle

ventedNon vented

Disk brake Disk brake CalipersCalipers

The part that receives hydraulic The part that receives hydraulic pressure from the master cyl.pressure from the master cyl.

Can Be fixed or sliding – Can Be fixed or sliding – Can have one or multiple pistons that Can have one or multiple pistons that

apply pressure to the brake pads. apply pressure to the brake pads. Calipers parts: Body, piston(s) square Calipers parts: Body, piston(s) square

cut seal & dust boot(s). cut seal & dust boot(s). Caliper is mounted to spindle or axle Caliper is mounted to spindle or axle

housing. housing.

Caliper types: Caliper types: FixedFixed

Caliper types : Caliper types : sliding or sliding or floatingfloating

Brake PadsBrake Pads Caliper presses brake Caliper presses brake

pads against rotor.pads against rotor. Brake pads can be made Brake pads can be made

of any combination of of any combination of metal, composite & metal, composite & synthetic fiber.synthetic fiber.

Must resist extreme heat Must resist extreme heat & pressure while being & pressure while being quiet, predictable and quiet, predictable and durable.durable.

Riveted and bonded Riveted and bonded types. types.

Friction material should Friction material should always be thicker than always be thicker than steel backing plate. steel backing plate.

Brake PadsBrake Pads

When your brake pads are When your brake pads are not replaced when warn out not replaced when warn out they will destroy the rotors.they will destroy the rotors.

Brake FluidBrake Fluid Brake fluid is a special Brake fluid is a special

glycol based fluid with a glycol based fluid with a high boiling point & high boiling point & good lubricating good lubricating properties.properties.

DOT stands for the DOT stands for the department of department of transportation – only use transportation – only use DOT 3 or 4 fluid unless DOT 3 or 4 fluid unless the manufacture the manufacture specifies something specifies something different.different.

Water absorption causes Water absorption causes internal corrosion & internal corrosion & lowers boiling point.lowers boiling point.

Brake linesBrake lines

Steel lines with a Steel lines with a double flare on the double flare on the ends connect the ends connect the master cylinder to master cylinder to each corner of the each corner of the car.car.

Flex lines carry Flex lines carry brake fluid from the brake fluid from the ends of the steel lines ends of the steel lines to the calipers and to the calipers and wheel cylinders.wheel cylinders.

Flex lines should be Flex lines should be inspected regularly inspected regularly

Steel Brake line w/ Steel Brake line w/ double flaredouble flare

Combination ValveCombination Valve The combination valve The combination valve

has three sections.has three sections. The metering sectionThe metering section The warning light The warning light

switchswitch The proportioning The proportioning

valvevalve The combination valve The combination valve

is typically located is typically located below the master below the master cylinder.cylinder.

Power Brake systemPower Brake system

The most common The most common type is called a type is called a vacuum booster. It vacuum booster. It uses vacuum from uses vacuum from the engine to assist the engine to assist in the application in the application of the brake pedal.of the brake pedal.

Located between Located between the firewall and the the firewall and the master cylinder .master cylinder .

Another type of Another type of booster is called booster is called the hydro- booster. the hydro- booster. It uses hydraulic It uses hydraulic pressure pressure generated by a generated by a power steering power steering pump to assist in pump to assist in the application of the application of the brakes.the brakes.

Brake Booster TypesBrake Booster Types

Power brake boosterPower brake booster

Bleeding the brake Bleeding the brake systemsystem

The Brake system must be totally free of air. The Brake system must be totally free of air. This is because air is compressible and will This is because air is compressible and will not transmit pedal motion to the brake pads / not transmit pedal motion to the brake pads / shoes.shoes.

To Bleed air out of a brake system each To Bleed air out of a brake system each device in the system has a small bleeder device in the system has a small bleeder screw at the high point of the part. Foot screw at the high point of the part. Foot pressure on the brake pedal pushes brake pressure on the brake pedal pushes brake fluid and air out the bleeder screw. Bleeding fluid and air out the bleeder screw. Bleeding can also be done with special equipment like can also be done with special equipment like a pressure bleeder or a vacuum bleeder.a pressure bleeder or a vacuum bleeder.

Brake Rotor / Drum Brake Rotor / Drum MachiningMachining

Brake Rotors and Brake Rotors and Drums can be Drums can be machined on a device machined on a device called a brake lathe.called a brake lathe.

Rotors and Drums Rotors and Drums should always be should always be checked for checked for minimum thickness minimum thickness or max dia.or max dia.

Under-sized Under-sized components components mustmust be be replaced. replaced.

ABSABS ABS stands for: Anti Lock Brake SystemABS stands for: Anti Lock Brake System ABS systems attempt to stop the wheels ABS systems attempt to stop the wheels

on the car from locking – this allows the on the car from locking – this allows the car to be “steered out of an accident”car to be “steered out of an accident”

This is accomplished by monitoring This is accomplished by monitoring wheel speed with sensors. Then a wheel speed with sensors. Then a computer is used to control valves that computer is used to control valves that switch brake pressure off and on 15 + switch brake pressure off and on 15 + times per second. This prevents wheel times per second. This prevents wheel lock. lock.

ABS SystemABS System

ABS PartsABS Parts

Diagnosing ABS Diagnosing ABS problemsproblems

Standard brake Standard brake system parts must be system parts must be in good condition.in good condition.

Scan tool can get Scan tool can get DTC’sDTC’s

Always disconnect Always disconnect and bleed pressure and bleed pressure from ABS system from ABS system before bleeding or before bleeding or doing any hydraulic doing any hydraulic work. work.

ALL BRAKE WORK !!!ALL BRAKE WORK !!! Must be checked by instructor before the Must be checked by instructor before the

wheel goes back on !!! No Exceptions !!! wheel goes back on !!! No Exceptions !!! Cycle brake pedal after all brake work to Cycle brake pedal after all brake work to

verify a firm pedal that will stop car.verify a firm pedal that will stop car. Be ready to stop the car if there is a Be ready to stop the car if there is a

brake system problem. ( use E – Brake )brake system problem. ( use E – Brake ) Torque all wheel lugs to factory Torque all wheel lugs to factory

specifications!specifications! Never allow people in car while doing Never allow people in car while doing

brake work.brake work.

Good Luck on your test!Good Luck on your test!