Automotive Brakes Systems Brake System Principles and Operation
Introduction • RPO Codes • Usually located in glove box or on spare tire cover. • Brakes information starts with “J”.
Brake System Principles and Operation • Base Brake Components
Brake System Principles and Operation • Brake Sub-Systems
Brake System Principles and Operation • Brake System Operation • Traditional brake systems change kinetic energy into heat energy through friction.
Brake System Principles and Operation • Changing Energy • Energy is never created or destroyed, just changed.
Brake System Principles and Operation • Power of Systems • Brake systems must have enough power to stop a vehicle at W.O.T.
Brake System Principles and Operation • Coefficient of Friction • Force to pull an object divided by the weight.
Brake System Principles and Operation • Coefficients of Friction and Temperature • Temperature can have negative effects on COF. These include fade and grab.
Brake System Principles and Operation • Traction / Weight and Balance • Keep in mind, the weight and balance of a vehicle effects the traction of that vehicle greatly. • Wheels with more traction must have more brake force applied than those with less traction.
Brake System Principles and Operation • Brake Fluid must do the following: • Maintains Viscosity • High Boiling Point • Non-Corrosive • Water Tolerant • Lubricates • Low Freezing Point
Brake System Principles and Operation • Answers to Brake Fluid FAQs • Three basic types: DOT 3, 4, and 5 • Brake Fluid will damage painted surfaces. Wash any spills immediately. • Conventional brake fluids are hydroscopic- that is they readily absorb moisture. Always keep brake fluid in a sealed container. • Never reuse brake fluid.
Brake System Principles and Operation • Answers to Brake Fluid FAQs • Dot 3 and 4 are conventional, and are interchangeable; but are not recommended to be interchanged. DOT 4 has a higher equilibrium reflux boiling point or ERBP. • DOT 5 is silicone based, does not absorb water, and has a higher ERBP yet. • According to some manufacturers, DOT 5 can cause seal deterioration in systems designed for DOT 3 or 4.
Brake System Principles and Operation • Answers to Brake Fluid FAQs • DOT 5.1 is a non-silicone-based polyglycol fluid that is clear to amber in color. It is more popular in Europe. It has a ERBP equal to DOT 5 fluid. According to brake fluid manufacturers, DOT 5.1 can be mixed with both DOT 3 and DOT 4. Automobile manufacturers have not acknowledged this yet. • Follow published Service Information.
Brake System Principles and Operation • Brake Fluid Concerns: • Contamination: • Mineral-Based Oils • Moisture • Air • Brake Fluid Disposal • EPA mandates that brake fluid is to be disposed of with used engine oil. • Do Not Wash Down the Drain.
Brake System Principles and Operation • Brake Linings • Composition is a mixture of “stuff”. Caution - Organic Linings may still contain asbestos. • Linings are produced in batches called “Lots”. Linings produced in two different lots may have different braking characteristics. • Lining Edge Codes identify the manufacturer, lot #, compound, & COF.
Overview • Brake System Principles and Operation • Base Brake Diagnosis • Master Cylinders & Hydraulic Systems • Balance Control Systems • Warning Systems • Wheel Bearings • Drum Brakes • Disc Brakes • Machining Drums and Rotors • Power Brake Boosters
Base Brake Diagnosis • Brake System Performance Evaluation • Common Brake Concerns Include: • Brake Vibration • Grabbing Brakes • Excessive Brake Pedal Effort • Pulling Brakes
Base Brake Diagnosis • Common Concerns cont. • Spongy Brake Pedal • Dropping Brake Pedal • Low Brake Pedal • Dragging Brakes • No Brake Pedal • Brake Warning Light On • Braking Noise
Base Brake Diagnosis • Brake System Inspection • Checking Brake Pedal Action Includes: • Pedal Height • Pedal Free-play • Reserve Distance • Checking Brake Fluid • Visual Inspection • Test Strips • Brake Fluid Boiling Point Tester
Base Brake Diagnosis • Checking for Leaks • Checking the Parking Brake • Disc Brake Inspection • Worn Out Friction Material • 3mm min. • Material Separation • Missing or Broken Pad Clips
Base Brake Diagnosis • Disc or Rotor Damage • Scoring • Cracking • Heat Checking • Rust Pitting • Worn Beyond Specs. • Excessive Runout • Lack of Parallelism • Material Transfer
Base Brake Diagnosis • Drum Brake Inspection • Frozen (Rusted) Adjusters • Spring Damage • Weakened Springs • Missing Springs • Broken Springs
Base Brake Diagnosis • Worn Out Friction Material • 1.5 mm min. • Material Separation • Drum Damage • Cracking • Hard Spots • Heat Checking • Scoring • Worn Beyond Specs. • Material Transfer