Modern Auto Tech Study Guide Chapters 71 & 73 Pages 1369 1444 Brake Systems 49 Points
1. Automotive systems use to stop, slow or to hold the wheels from turning. Brake, Friction Brake, Fraction Brake, Traction
2. The two common types of brakes used on vehicles are and brakes.
3. Brake are forced against the disc and brake are forced against the drum to stop. Pads, Shoes Lines, Slippers Cables, Rivets
4. brakes typically do 60% to 80% of the total vehicle braking, so they are often fit with the more heat resistant and efficient disc design. NOTE: Heat causes brake fade Disc brakes fade less! Front Service Parking
5. brakes typically do 20% to 40% of the total vehicle braking, so they are often fit with the less heat resistant and less efficient drum design. NOTE: Heat causes brake fade Drum brakes fade more! Rear Service Parking
6. A brake system uses liquid to transmit motion & pressure undiminished from the pedal to the disc calipers and drum wheel cylinders. [Pascal s law] (Force = Pressure x Area) Force Psi A Pneumatic Hydraulic Electronic
7. Hydraulics are used since will not compress, and when is applied in a closed system it is exerted equally in all directions so it can increase or decrease force & motion. Liquids, Pressure
8. When the driver depresses the brake pedal, is applied to the master cylinder pistons. The pressure built up is transferred undiminished through brake lines to the brakes at each corner of the car. Force Force Pressure Area
9. The tandem or master cylinder uses two separate hydraulic pistons and reservoirs to develop the pressure that gets sent to the brakes to apply them. This is a safe way of limiting failure of all the brakes. Dual
10. brakes use either engine vacuum or power steering pressure to ease pedal application. Power Tower Shower
11. The vacuum is the large diaphragm device located between the master cylinder and the brake pedal which assists the driver in applying the brakes. It does not increase system pressure! Toaster Booster Turbine
12. DOT 3 brake fluid must absorb (hygroscopic/desiccant), must hold its, have a high boiling point, not be corrosive, must lubricate brake parts & have a very low freeze point. Water, Viscosity
13. Brake lines are made of double wall tubing. Flexible brake are made of heavy rubber, which is reinforced to prevent expansion (bulging) as well as collapse. Steel, Hoses
14. Brake hydraulic systems can be (front/rear) or (corner to corner) split to deliver fluid to the calipers and wheel cylinders. Longitudinally, Diagonally Transversely, Longitudinally Squarely, Roundabout
15. When fluid pressure is applied to a brake caliper, the moves the pads against the rotor. Piston Cylinder Block
16. Disc brake pads have a steel backing and a made of heat resistant friction material. Lining Shining Refining
17. The brake disc is sometimes referred to as the. It is made of cast iron and steel. Rotors can be either vented or solid. Vented rotors have fins for air to flow through. This prevents brake fade. Rotor Disco Frisbee
18. The drum brake shoes fasten to a brake plate with springs and various hold down clips. Backing Cracking Tracking
19.The wheel is a double ended hydraulic piston unit that forces shoes against the drum. Cylinder Block Piston
20. Wheel cylinders as well as calipers and some master cylinders have screws to allow the system to be bled of air if it should enter. Air in the hydraulic system gives a spongy pedal feel. Slider Bleeder Excreeder
21.The brake shoe is the forward facing shoe (leading) and is often shorter than the other. Primary Secondary College
22.The brake shoe is the rearward facing shoe (trailing) and usually has a longer lining. Primary Secondary College
23. or return springs pull the shoes back toward the wheel cylinder when the pedal is released. Hold down springs keep the brake parts held in place against the backing plate. Retracting Retracing Refacing
24. Drum brakes have a self adjuster with a wheel mechanism to automatically adjust shoe to drum clearance when the brakes are applied while the vehicle is moving backwards. Star Car Bar
25.The brake provide the smooth surface for the brake shoe linings to rub against for stopping. Drums Discs Cyliners
26.Brake systems have a switch used to turn on the brake lights, a fluid switch to warn of a low fluid level in the master cylinder, and a pressure differential switch to warn the driver of a major failure in one half of the hydraulic system. Parking brake switches are also used. Stop Light, Low
27. A or hold off valve is placed in the front brake system to prevent the front brakes from applying until the rear system builds up sufficient pressure. (75 135 psi) Metering Proportioning Pressure Differential
28. A or balance valve is placed in the rear system to equalize braking action front to rear. This ensures the proper percentage of braking to front & rear brakes. Metering Proportioning Pressure Differential
29. The brake system uses the drum shoes and disc pads to hold the vehicle while parked. Parking Service Electric
30. The parking brake system is operated by cables and levers so that it will still work if both of the hydraulic systems fail. That s why it is sometimes called emergency brake. The parking brake system usually operates the rear brake system, but there are exceptions. Mechanically Electrically Hydraulically
~~~ 31.The brake system (ABS) uses wheel sensors, a computer, and a unit to modulate (vary & control) pressure to the corners of the vehicle. Anti Lock, Speed
32. For maximum stopping power, you want the tires to almost, but not quite. ABS does this! Lock or Skid
7 Pulses (peak to peak) in.1 second = 70 times per second during all driving
33. Besides stopping distances, ABS vehicles are also able to during panic stops. Reducing, Spin Decreasing, Steer Increasing, Skid
34. Permanent magnet, sensors produce AC signals that are fed to the ABS control module (BCM). The wheel speed sensor signals if the wheel is spinning, slowing, or skidding. Wheel Speed
35. An ABS is a separate hydraulic circuit that feeds out to one or more wheel cylinders or caliper pistons. One channel brakes are usually found on pick up trucks and are referred to as RWAL. Flannel Channel Path
36. channel ABS has a separate hydraulic control circuit for each wheel. It is the most effective and most common anti lock brake system found on late model vehicles. (a must with TCS & DSC) Four Two Single
37. Apply pressure, but do not the brake pedal during panic stops on an ABS equipped vehicle. Pump Push Stomp
38. systems are prevent the wheels from spinning and losing traction on hard acceleration. Stability control systems use lateral & longitudinal g sensors & yaw sensors for more vehicle control. Traction Control
39. Besides reducing engine power, the TCS use the ABS system to apply the brakes during acceleration Ask about Stability Control