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Brakes Brakes Presentation Transcript

  • Brakes
  • Types
    • Parking Brake
    • Service Brake
      • Hydraulic
        • Disc Brakes
        • Drum Brakes
        • Dual System
      • Antilock Brake System (ABS)
  • Play Principles of Braking
  • Brake System Principles
    • Kinetic Energy
    • Mass
    • Weight
    • Speed
    • Inertia and Momentum
  • Coefficient of Friction Video
  • Parking Brake
    • Not an “Emergency” Brake
    • Used specifically to keep a parked vehicle from moving
    • Usually on rear wheels only
    • Mechanically operated
      • Static Friction: at rest friction- More friction
      • Kinetic Friction: in motion friction- less friction
  • Typical Parking Brake
  • Play Parking Break Video
  • Play Parking Brake Adjustment Video
  • Service Brakes
    • Primary Braking System
    • Should be stronger than the engine
    • Hydraulic Operated
      • Can be Vacuum, Hydro or Motor assisted
      • Disc System
      • Drum System
      • Dual System
  • Typical System
  • Hydraulic Principles
    • Fluids cannot be compressed
    • Fluids can transmit Movement
      • Acts “Like a steel rod” in a closed container
      • Master cylinder transmits fluid to wheel cylinder or caliper piston bore.
    • Fluids can transmit and increase force
          • Force
    Area Pressure
  • Hydraulics
    • Simplified Hydraulic Brake System
    • Drum Brake
    • Master Cylinder
    • Disk Brake
  • Hydraulic pressure is distributed equally in all directions
  • Same line pressure to all wheels
  • The Hydraulic pressure is the same, but the applied force can be changed by the piston size
  • The applied pressure can be raised or lowered by piston size
  • Play Hydraulic Pressure Video
  • Brake Pedal Design Advantage by Leverage
    • First Mechanical Advantage is Driver’s foot
    • Length of Lever determines force applied
    • Uses Fulcrum
    • Pedal Ratio
    10 2 5:1 2.5 inches 5 0.5 inch
  • Play Break Pedal Leverage Video
  • System Basics
    • Hydraulic actuation allows multiplication of pedal force.
    • In this system, a 10lb force on the pedal produces 360 lbs of force at the friction surface.
  • Play Break Lines & Hose Video
  • Brake Fluid
    • Properties of Brake Fluid
      • Does not thicken or then with changing heat
      • Must not boil
      • Must be compatible with brake parts material
      • Must lubricate internal parts
      • Must not evaporate easily
  • Brake Fluid types
    • DOT 3 and 4-
      • Polyglycol based
      • Most common
      • Compatible with one another
      • Inexpensive
      • Destroys paint
      • Ruined by moister
    • DOT 5-
      • Silicone Based
      • Used only for heavy duty applications
      • Not Compatible with 4&5
      • Very Expensive
      • Does not damage paint
    DOT= Department of Transportation High #= High stands, quality and boiling point
  • Fluid Contaminates
    • Moister- Lowers boiling point
      • water boils @ 212*F DOT 3 boils @ 401*F
    • Petroleum Based Product-
      • soften rubber parts causing swelling
    • Dirt & Debris-
      • causes corrosion and clogs
    • Air and Vapors-
      • Compressible prevents pressure from reaching brakes
  • Play Break Fluid Video
  • Master Cylinder
    • Provides a reservoir for brake fluid and contains the driving pistons in the hydraulic circuit
    • 2 Types
    • Front - Rear split
    • -One piston for front brakes and one for rear
    • -If a leak occurs you could lose front brakes
    • Diagonally split
    • -One piston drives one front wheel and one rear wheel
    • -Diagonal layout allows you to maintain directional control if a leak occurs
  • Play Tandem Master Cylinder Video
  • Play Divide System Video
  • Power Booster in closed position
  • Play Power Booster Video
  • Drum Brakes
    • Expanding shoes create force on the inner surface of the drum
    • Used on the rear of some trucks and SUV’s
    • Self-energizing design requires less activation force
    • Require periodic adjustment
  • Drum Brake System
  • Vented Rotors Vented Rotors have Fins in the spaces between their machined surfaces. These spaces allow air to pass through, which helps carry heat away.
  • Nonvented Rotor Non Vented Rotors are used on smaller vehicles, and have no cooling fins
  • Play Brake Disc Video
  • Disc Brake Caliper Assembly
  • Caliper Types
    • There are 2 types of Calipers
    • Fixed
      • Calipers are disc brakes that use a caliper that is FIXED in position and does not slide. They have pistons on both sides of the disc. There may be 2 or 4 pistons per caliper
    • Floating
      • Much more common
      • Single Piston
      • Easier to work with
      • On “inboard” side of caliper
  • Fixed Caliper
    • Motorcycles and some import trucks and cars use this type
    • Similar to bicycle brakes
  • Sliding Caliper
    • Applies pressure to two pads on opposite sides of rotor
    • Caliper
      • Sliding
      • Fixed
    • Friction Material exposed to air
  • Fixed Caliper
    • Applies two pistons to opposite sides of rotor
    • Caliper stays stationary
    • Disc Brakes require higher hydraulic pressure
  • Play Disc Brake Calipers Video
  • Diagnosis Several different types of Complaints Noise Pulsation Pedal travel More later…
  • Brake Noise Wear Indicator
  • Brake Pulsation Usually a warped Rotor Rotor needs trued on a brake lathe
  • Pedal Travel NO BRAKES!!!!
    • Excessive pedal travel
    • Pedal feels soft and squishy
    • Requires excessive effort to stop vehicle or my cause brakes to not function at all
  • Play Drum Brake Inspection Video
  • Play Disc Brake Inspection Video
  • Anti-Lock Brakes
    • A locked (sliding) wheel offers less braking force than a decelerating rolling wheel
    • The locked wheel also produces little lateral force, preventing steering control
    • Anti-Lock systems (ABS) monitor wheel lock-up and modulate brake pressure to provide controlled braking under most circumstances
  • Play ABS Principles Video
  • Anti-Lock Brakes
    • System can have 2, 3 or 4 channels
    • Trucks typically use 3 channel with only one sensor for the rear axle
    • Most modern cars use 4 channel system
    • Wheel speed sensors monitor each wheel speed
    • ABS controller and high-pressure pump increase or reduce pressure to wheels in order to maintain consistent wheel speeds
  • Play ABS video
  • Play Drum, Disc, & ABS Video
  • Other Braking Systems
    • Air Brakes
    • Exhaust Brakes
    • Electric or Trailer Brake
  • Play Disc Brake Replacement Video
  • Play Replacing The Rotor Video
  • Play Drum Brake Replacement Video