BRAKE SYSTEMSBRAKE SYSTEMS

PURPOSEPURPOSE

►TO STOP THE VEHICLE IN THE TO STOP THE VEHICLE IN THE SHORTEST DISTANCE POSSIBLE SHORTEST DISTANCE POSSIBLE WHILE MAINTAINING CONTROL.WHILE MAINTAINING CONTROL.

How do Brakes WorkHow do Brakes Work

►Drivers need to be able to activate Drivers need to be able to activate brakes as requiredbrakes as required

►This is accomplished by foot pedals or This is accomplished by foot pedals or hand levers.hand levers.

How do Brakes Work?How do Brakes Work?

4 TYPES OF BRAKING 4 TYPES OF BRAKING SYSTEMSSYSTEMS

►1. HYDRAULIC1. HYDRAULIC►2. COMPRESSED AIR2. COMPRESSED AIR►3. MECHANICAL 3. MECHANICAL ►4. ELECTRICAL4. ELECTRICAL

HYDRAULIC BRAKING HYDRAULIC BRAKING SYSTEMSSYSTEMS

► PASCALS LAW:PASCALS LAW:► WHEN A FORCE IS APPLIED TO A LIQUID IN A WHEN A FORCE IS APPLIED TO A LIQUID IN A

CLOSED CONTAINER IT IS TRANSFERRED CLOSED CONTAINER IT IS TRANSFERRED EQUALLY AND UNDIMINISHED IN ALL EQUALLY AND UNDIMINISHED IN ALL DIRECTIONS.DIRECTIONS.

►A FLUID TRANSMITS:A FLUID TRANSMITS:► 1. MOTION1. MOTION► 2. PRESSURE2. PRESSURE► 3. FORCE3. FORCE

Force IncreaseForce Increase

►Brake force is increased by 2 methods:Brake force is increased by 2 methods:

1) Hydraulic Advantage 1) Hydraulic Advantage

2) Mechanical Advantage2) Mechanical Advantage

Hydraulic AdvantageHydraulic Advantage

►Fluids cannot be compressedFluids cannot be compressed►A fluid pressurized by a small piston A fluid pressurized by a small piston

will move a larger piston with greater will move a larger piston with greater force, but less distanceforce, but less distance

LeversLevers

LeversLevers►The brake pedal gives a The brake pedal gives a mechanical advantage mechanical advantage because it acts as a leverbecause it acts as a lever

►The input into the braking The input into the braking system is increased due to system is increased due to this advantagethis advantage

Hydraulic CircuitsHydraulic Circuits

Wheel Cylinder

BRAKE PEDAL

Brake Caliper

Brake Warning Light

Rear Brake Lights

Steel Brake Lines

Wheel Cylinder

Brake Caliper

Master Cylinder

COMPONENTSCOMPONENTS

►MASTER CYLINDER:MASTER CYLINDER:►PURPOSE:PURPOSE:

►1. STORE FLUID1. STORE FLUID►2. ACTIVATES THE BRAKES2. ACTIVATES THE BRAKES►3. PROVIDES OUTPUTS FOR 2 3. PROVIDES OUTPUTS FOR 2

CIRCUITS....Why?CIRCUITS....Why?

Master CylinderMaster Cylinder

►PRIMARY SIDE:PRIMARY SIDE:► IS CLOSEST TO FIREWALL.IS CLOSEST TO FIREWALL.

►SECONDARY SIDE:SECONDARY SIDE:► IS FARTHEST FROM FIREWALL.IS FARTHEST FROM FIREWALL.

►DUAL MASTER CYLINDERS:DUAL MASTER CYLINDERS:► PRIMARY SIDE IS APPLIED BY PRIMARY SIDE IS APPLIED BY

MECHANICAL FORCE, THE SECONDARY MECHANICAL FORCE, THE SECONDARY SIDE IS APPLIED BY HYDRAULIC SIDE IS APPLIED BY HYDRAULIC PRESSUREPRESSURE

WHEEL CYLINDERS:WHEEL CYLINDERS:PURPOSE:PURPOSE:►CONVERTS HYDRAULIC PRESSURE CONVERTS HYDRAULIC PRESSURE

INTO MECHANICAL FORCE.INTO MECHANICAL FORCE.Found Where?: Found Where?: used in drum type systems to force used in drum type systems to force

the brake shoes against the the brake shoes against the drums.drums.

DOUBLE ENDED WHEEL DOUBLE ENDED WHEEL CYLINDERCYLINDER

Drum Brake SystemsDrum Brake Systems

►Function: To slow wheel speed down Function: To slow wheel speed down by pushing shoes against the inside of by pushing shoes against the inside of a druma drum

BRAKE SHOE DESIGNBRAKE SHOE DESIGN

► FRONT SHOE PRIMARYFRONT SHOE PRIMARY► REAR SHOE SECONDARY.REAR SHOE SECONDARY.► LEADING TYPE SHOE (PRIMARY) HAS LEADING TYPE SHOE (PRIMARY) HAS

SELF ENERGIZING OR SERVO ACTION.SELF ENERGIZING OR SERVO ACTION.► USES A SOLID ANCHOR BETWEEN USES A SOLID ANCHOR BETWEEN

SHOES.SHOES.

BRAKE DRUMSBRAKE DRUMS► CONSTRUCTION:CONSTRUCTION:► CAST IRONCAST IRON► CAST ALUMINUM WITH CAST IRON INSERTCAST ALUMINUM WITH CAST IRON INSERT► SOME DRUMS ARE EQUIPPED WITH SOME DRUMS ARE EQUIPPED WITH

FINS :THESE ASSIST IN HEAT DISSIPATION.FINS :THESE ASSIST IN HEAT DISSIPATION.

BRAKE DRUMSBRAKE DRUMS► BRAKE DRUM SERVICING:BRAKE DRUM SERVICING:► SCORED DRUM:SCORED DRUM:► DRUM SHOWS VISIBLE SIGNS OF DAMAGE DRUM SHOWS VISIBLE SIGNS OF DAMAGE

USUALLY DUE TO RIVETS IN SHOES USUALLY DUE TO RIVETS IN SHOES CONTACTING DRUM.CONTACTING DRUM.

►METHODS OF TURNING A BRAKE METHODS OF TURNING A BRAKE DRUM:DRUM:

►Machine inside Machine inside

surface of drumsurface of drum

Measure to make sureMeasure to make sure

it’s still within Specs.it’s still within Specs.

after machiningafter machining

Disc Brake SystemsDisc Brake Systems

►Function:Function:►Slows wheel speed by squeezing 2 Slows wheel speed by squeezing 2

brake pads against a disc (rotor)brake pads against a disc (rotor)

DISC BRAKE SYSTEMSDISC BRAKE SYSTEMS

►ADVANTAGES:ADVANTAGES:►1. BETTER COOLING1. BETTER COOLING►2. LESS BRAKE FADE2. LESS BRAKE FADE►3. EASIER TO MAINTAIN3. EASIER TO MAINTAIN►4. SELF CLEANING4. SELF CLEANING►5. SELF ADJUSTING5. SELF ADJUSTING►6. NO ADJUSTMENTS REQUIRED6. NO ADJUSTMENTS REQUIRED► (ON FRONT WHEEL SYSTEMS)(ON FRONT WHEEL SYSTEMS)

DISADVANTAGESDISADVANTAGES

►1. OPEN TO ROAD SPLASH1. OPEN TO ROAD SPLASH►2. HIGHER TEMPERATURE 2. HIGHER TEMPERATURE

DEVELOPED IN CALIPER (HIGHER DEVELOPED IN CALIPER (HIGHER TEMPERATURE BRAKE FLUID IS TEMPERATURE BRAKE FLUID IS NEEDED)NEEDED)

►3. GREATER HYDRAULIC PRESSURE 3. GREATER HYDRAULIC PRESSURE REQUIRED TO STOP VEHICLEREQUIRED TO STOP VEHICLE

►4. NO “SELF ENERGIZING” ACTION4. NO “SELF ENERGIZING” ACTION

►BRAKE DISC OR ROTOR:BRAKE DISC OR ROTOR:► 1. CAST IRON1. CAST IRON► 2. CAST ALUMINUM ALLOY2. CAST ALUMINUM ALLOY► TYPES:TYPES:► 1. SOLID1. SOLID► 2. VENTED- HAS AIR VENTS TO PROVIDE 2. VENTED- HAS AIR VENTS TO PROVIDE

BETTER COOLING.BETTER COOLING.

► SERVICE:SERVICE:► 1. CHECK FOR LATERAL RUNOUT, USING A 1. CHECK FOR LATERAL RUNOUT, USING A

DIAL INDICATORDIAL INDICATOR► 2. CHECK FOR SCORING/CORROSION2. CHECK FOR SCORING/CORROSION► 3. CHECK THICKNESS OF ROTOR USING A 3. CHECK THICKNESS OF ROTOR USING A

MICROMETERMICROMETER

CALIPERSCALIPERS

►TYPES:TYPES:►1. FIXED TYPE - HAS PISTONS ON 1. FIXED TYPE - HAS PISTONS ON

BOTH SIDES OF THE BRAKE DISC. BOTH SIDES OF THE BRAKE DISC. TWO OR FOUR TWO OR FOUR

►2. FLOATING TYPE - HAS PISTON/S 2. FLOATING TYPE - HAS PISTON/S ON ONE SIDE OF THE ROTOR ON ONE SIDE OF THE ROTOR ONLY.ONLY.

► FIXED CALIPERFIXED CALIPER

►FLOATINGFLOATING►CALIPERCALIPER

OFF ONOFF ON

DIFFERENCE IN DISC BRAKE DIFFERENCE IN DISC BRAKE MASTER CYLINDERMASTER CYLINDER

►1. NO RESIDUAL CHECK VALVE ON 1. NO RESIDUAL CHECK VALVE ON DISC BRAKE SIDE.DISC BRAKE SIDE.

►2. LARGER RESERVOIR ON DISC 2. LARGER RESERVOIR ON DISC SIDESIDE

►3. LARGER BORE SIZE.3. LARGER BORE SIZE.►4. HIGHER BOILING POINT OF 4. HIGHER BOILING POINT OF

BRAKE FLUID.BRAKE FLUID.

TYPES OF PADSTYPES OF PADS

►1. RIVETED1. RIVETED►2. BONDED2. BONDED►3. BOLTED3. BOLTED►*NOTE* MAKE SURE ANTI- RATTLE *NOTE* MAKE SURE ANTI- RATTLE

CLIPS ARE INSTALLED AND CLIPS ARE INSTALLED AND RETAINER TABS ARE CLINCHED RETAINER TABS ARE CLINCHED PROPERLY.CHECK M/F SPEC.PROPERLY.CHECK M/F SPEC.

RIVITED PADSRIVITED PADS

BONDED PADSBONDED PADS

BRAKE FLUIDBRAKE FLUID► 1. DO NOT REUSE BRAKE FLUID.1. DO NOT REUSE BRAKE FLUID.► 2. BRAKE FLUID MUST BE COMPATIBLE.2. BRAKE FLUID MUST BE COMPATIBLE.► CORROSIVE RESISTANT,HAVE A HIGH BOILING CORROSIVE RESISTANT,HAVE A HIGH BOILING

POINT(256 DEGREES C),HAVE A LOW FREEZING POINT POINT(256 DEGREES C),HAVE A LOW FREEZING POINT & CONSISTENT VISCOSITY.& CONSISTENT VISCOSITY.

► S.A.E. RATINGS. SOCIETY OF AUTOMOTIVE ENGINEERS.S.A.E. RATINGS. SOCIETY OF AUTOMOTIVE ENGINEERS.► DOT RATINGS – 3,4,5 (5 IS SILCONE BASED AND NOT DOT RATINGS – 3,4,5 (5 IS SILCONE BASED AND NOT

COMPATIBLE WITH 3 OR 4 DO NOT MIX) COMPATIBLE WITH 3 OR 4 DO NOT MIX) ► DRUM BRAKES:DRUM BRAKES:► MINIMUM BOILING POINT – 374 F / 191 CMINIMUM BOILING POINT – 374 F / 191 C► DISC BRAKES:DISC BRAKES:► MUST SAY FOR DISC BRAKES!MUST SAY FOR DISC BRAKES!► MINIMUM BOILING POINT – 475 F / 246 CMINIMUM BOILING POINT – 475 F / 246 C

BRAKE LINESBRAKE LINES

► 1. MUST BE DOUBLE WALL STEEL TUBE.1. MUST BE DOUBLE WALL STEEL TUBE.► *NOTE* DO NOT USE COPPER!*NOTE* DO NOT USE COPPER!► 2. ALL ENDS MUST BE DOUBLE FLARED.2. ALL ENDS MUST BE DOUBLE FLARED.► 3. DO NOT USE COMPRESSION 3. DO NOT USE COMPRESSION

FITTINGS.FITTINGS.► 4. USE A TUBE BENDER.4. USE A TUBE BENDER.► 5. FRONT OR REAR FLEX LINES MUST 5. FRONT OR REAR FLEX LINES MUST

NOT BE CRACKEDNOT BE CRACKED

BLEEDING THE SYSTEMBLEEDING THE SYSTEM► METHODS:METHODS:► 1. MANUAL1. MANUAL (TWO MAN OPERATION) (TWO MAN OPERATION)► A. PUMP BRAKE SLOWLY.A. PUMP BRAKE SLOWLY.► B. DO NOT PUSH BRAKE PEDAL TO FLOOR. DAMAGE B. DO NOT PUSH BRAKE PEDAL TO FLOOR. DAMAGE

TO TO MASTER CYLINDER MAY RESULT. MASTER CYLINDER MAY RESULT.► C. CHECK FLUID LEVEL FREQUENTLY TO PREVENT C. CHECK FLUID LEVEL FREQUENTLY TO PREVENT

PUMPING MASTER CYLINDER DRY. PUMPING MASTER CYLINDER DRY.► 2. BLEEDER BALL2. BLEEDER BALL► THE BLEEDER BALL USES PRESSURIZED BRAKE FLUID THE BLEEDER BALL USES PRESSURIZED BRAKE FLUID

TO FORCE AIR OUT OF SYSTEM.TO FORCE AIR OUT OF SYSTEM.► 3. SURGE BLEEDING3. SURGE BLEEDING► THIS IS A COMBINATION OF 1 & 2THIS IS A COMBINATION OF 1 & 2► 4. GRAVITY BLEEDING4. GRAVITY BLEEDING – OPEN BLEEDER SCREWS AND – OPEN BLEEDER SCREWS AND

LET GRAVITY DOTHE JOB.LET GRAVITY DOTHE JOB.

BRAKE BLEEDINGBRAKE BLEEDING

CONTROL VALVES:CONTROL VALVES:PRESSURE DIFFERENTIAL VALVE & PRESSURE DIFFERENTIAL VALVE &

SWITCH ASSEMBLY:SWITCH ASSEMBLY:

► PURPOSE:PURPOSE:► TO WARN DRIVER OF PRESSURE DROP TO WARN DRIVER OF PRESSURE DROP

ON EITHER SIDE OF THE SYSTEM.ON EITHER SIDE OF THE SYSTEM.►OPERATION:OPERATION:► PISTON WILL MOVE TO THE LOW PISTON WILL MOVE TO THE LOW

PRESSURE SIDE OF THE SYSTEM PRESSURE SIDE OF THE SYSTEM CAUSING THE PIN IN THE SWITCH TO CAUSING THE PIN IN THE SWITCH TO TOUCH THE RAMPS ON THE PISTON TOUCH THE RAMPS ON THE PISTON CLOSING THE CIRCUIT CAUSING THE CLOSING THE CIRCUIT CAUSING THE LAMP IN THE DASH TO LIGHT.LAMP IN THE DASH TO LIGHT.

►PROPORTIONING VALVE:PROPORTIONING VALVE:► LOCATION:LOCATION:► BETWEEN THE PRESSURE DIFFERENTIAL VALVE BETWEEN THE PRESSURE DIFFERENTIAL VALVE

AND THE REAR WHEEL DRUM BRAKE SYSTEM.AND THE REAR WHEEL DRUM BRAKE SYSTEM.► FUNCTION:FUNCTION:► PROVIDES A BALANCED BRAKING ACTION PROVIDES A BALANCED BRAKING ACTION

BETWEEN FRONT DISC BRAKE AND REAR DRUM BETWEEN FRONT DISC BRAKE AND REAR DRUM BRAKES UNDER A WIDE RANGE OF BRAKES UNDER A WIDE RANGE OF CONDITIONS.CONDITIONS.

► REDUCES REAR BRAKE HYDRAULIC PRESSURE REDUCES REAR BRAKE HYDRAULIC PRESSURE TO BALANCE REAR BRAKE SELF-ENERGIZING TO BALANCE REAR BRAKE SELF-ENERGIZING ACTION AGAINST FRONT DISC BRAKE NON-ACTION AGAINST FRONT DISC BRAKE NON-SELF-ENERGIZING ACTION.SELF-ENERGIZING ACTION.

► PREVENTS REAR WHEEL LOCK-UPPREVENTS REAR WHEEL LOCK-UP

►METERING VALVE:METERING VALVE:► LOCATION:LOCATION:► BETWEEN THE PRESSURE DIFFERENTIAL VALVE BETWEEN THE PRESSURE DIFFERENTIAL VALVE

AND THE FRONT DISC BRAKES CALIPERS.AND THE FRONT DISC BRAKES CALIPERS.► FUNCTION:FUNCTION:► PREVENTS FRONT DISC BRAKES FROM DOING PREVENTS FRONT DISC BRAKES FROM DOING

ALL THE BRAKING ACTION AT SLOW SPEED ALL THE BRAKING ACTION AT SLOW SPEED STOPS. HELPS TO INCREASE DISC PAD LIFE.STOPS. HELPS TO INCREASE DISC PAD LIFE.

► 2. PREVENTS FRONT DISC BRAKES FROM 2. PREVENTS FRONT DISC BRAKES FROM APPLYING UNTIL MASTER CYLINDER PRESSURE APPLYING UNTIL MASTER CYLINDER PRESSURE REACHES 100-120 PSI TO OVER COME REAR REACHES 100-120 PSI TO OVER COME REAR DRUM BRAKE SHOE RETRACTION SPRINGS.DRUM BRAKE SHOE RETRACTION SPRINGS.

► 3. WHEN BLEEDING FRONT DISC BRAKES 3. WHEN BLEEDING FRONT DISC BRAKES EQUIPPED WITH A METERING VALVE THE VALVE EQUIPPED WITH A METERING VALVE THE VALVE MAY HAVE TO BE HELD OPEN MANUALLY.MAY HAVE TO BE HELD OPEN MANUALLY.

►COMBINATION VALVE:COMBINATION VALVE:►MAY CONTAIN A METERING VALVE, MAY CONTAIN A METERING VALVE,

PROPORTIONING VALVE & OR A PROPORTIONING VALVE & OR A PRESSURE DIFFERENTIAL VALVE.PRESSURE DIFFERENTIAL VALVE.

ABS Braking SystemsABS Braking Systems

► Purpose: to provide directional stability and steer Purpose: to provide directional stability and steer ability during brakingability during braking

► TypesTypes► Integral – combines the master cylinder, power Integral – combines the master cylinder, power

booster and antilock system into one device (newer booster and antilock system into one device (newer systems)systems)

► Component – uses existing master cylinder and Component – uses existing master cylinder and power booster, then adds the necessary power booster, then adds the necessary components to make the system anti lock (earlier components to make the system anti lock (earlier systems)systems)

ABSABS

► Understanding ABSUnderstanding ABS► We need to know slippage ratio. 0% slippage ratio is We need to know slippage ratio. 0% slippage ratio is

a rolling wheel, 100% slippage is a skidding wheel.a rolling wheel, 100% slippage is a skidding wheel.►According to research a slippage ratio of 22% provides According to research a slippage ratio of 22% provides

the best braking possible and 8% still allows us to steer the best braking possible and 8% still allows us to steer the vehiclethe vehicle

► Therefore : ABS needs to work in a range of 8 to 30%Therefore : ABS needs to work in a range of 8 to 30%► Next we need to know the coefficient of friction, Next we need to know the coefficient of friction,

which changes with the road surface. Dry concrete which changes with the road surface. Dry concrete provides the best value of 1.00, ice is the worst at a provides the best value of 1.00, ice is the worst at a value of 0.10. These values are put into the value of 0.10. These values are put into the computer to help control the system.computer to help control the system.

ABSABS

►All systems use speed sensors. They All systems use speed sensors. They are monitored by a computer, if the are monitored by a computer, if the computer senses a sudden change in computer senses a sudden change in wheel speed at any wheel it starts to wheel speed at any wheel it starts to modulate the brake pressure to that modulate the brake pressure to that wheel and keeps it within the braking wheel and keeps it within the braking (slippage) range.(slippage) range.

► 1.  Compressor1.  Compressor► 2.  Supply, Primary and Secondary Air Tanks2.  Supply, Primary and Secondary Air Tanks► 3.  Low Pressure Indicator Switch3.  Low Pressure Indicator Switch► 4.  Safety Valve4.  Safety Valve► 5.  Drain Valves (Manual & Automatic)5.  Drain Valves (Manual & Automatic)► 6.  Governor6.  Governor► 7.  Single Check Valve7.  Single Check Valve► 8.  Pressure Control Check Valve8.  Pressure Control Check Valve► 9.  Air Gauge\9.  Air Gauge\► 10.  Dual System Foot Brake Valve10.  Dual System Foot Brake Valve► 11.  Quick Release Valve11.  Quick Release Valve► 12.  Service Brake Chamber12.  Service Brake Chamber► 13.  Slack Adjuster13.  Slack Adjuster► 14.  Relay Valve 14.  Relay Valve ► 15.  Spring Parking Brake15.  Spring Parking Brake► 16.  Quick Release and Double Check Valve Combination16.  Quick Release and Double Check Valve Combination► 17.  Stop Light Switch17.  Stop Light Switch► 18A.  Inversion Relay Valve18A.  Inversion Relay Valve► 18B.  Spring Brake Control Valve18B.  Spring Brake Control Valve► 19.  Air Dryer19.  Air Dryer► 20.  ABS Electronic Control Unit, Modulator Valves, Sensors and Tooth Rings20.  ABS Electronic Control Unit, Modulator Valves, Sensors and Tooth Rings► 20A.  Front Axle Valve Package20A.  Front Axle Valve Package► 20B.  Rear Axle Valve Package20B.  Rear Axle Valve Package► 21.  Two-Line Tractor Protection Valve (Non-Automatic Type)21.  Two-Line Tractor Protection Valve (Non-Automatic Type)► 22.  Hand Control Valve - Trailer Service Brakes22.  Hand Control Valve - Trailer Service Brakes► 23.  Double Check Valve23.  Double Check Valve► 24.  Double Check Valve24.  Double Check Valve► 25.  Manifold Dash Valve25.  Manifold Dash Valve