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FIGURE 4–1 Energy which is the ability to perform work exists in many forms. Automotive Brake Systems, 5/e By James D. Halderman 1 Copyright © 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 • All rights reserved. FIGURE 4–2 Kinetic energy increases in direct proportion to the weight of the vehicle. Automotive Brake Systems, 5/e By James D. Halderman 2 Copyright © 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 • All rights reserved. FIGURE 4–3 Kinetic energy increases as the square of the of any increase in vehicle speed. Automotive Brake Systems, 5/e By James D. Halderman 3 Copyright © 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 • All rights reserved. FIGURE 4–4 Inertia creates weight transfer that requires the front brakes to provide most of the braking force. Automotive Brake Systems, 5/e By James D. Halderman 4 Copyright © 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 • All rights reserved. FIGURE 4–5 Front wheel drive vehicles have most of their weight over the front wheels. Automotive Brake Systems, 5/e By James D. Halderman 5 Copyright © 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 • All rights reserved. FIGURE 4–6 A first-class lever increases force and changes the direction of the force. Automotive Brake Systems, 5/e By James D. Halderman 6 Copyright © 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 • All rights reserved. FIGURE 4–7 A second class lever increases the force in the same direction as the applied force. Automotive Brake Systems, 5/e By James D. Halderman 7 Copyright © 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 • All rights reserved. FIGURE 4–8 A third-class lever reduces force but increases the speed and travel of the resulting work. Automotive Brake Systems, 5/e By James D. Halderman 8 Copyright © 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 • All rights reserved. FIGURE 4–9 A brake pedal assembly is a second-class lever design that provides a 5 to 1 mechanical advantage. Automotive Brake Systems, 5/e By James D. Halderman 9 Copyright © 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 • All rights reserved. FIGURE 4–10 The coefficient of friction in this example is 0.5. Automotive Brake Systems, 5/e By James D. Halderman 10 Copyright © 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 • All rights reserved. FIGURE 4–11 The type of friction material affects the coefficient of friction which is just 0.05 in this example. Automotive Brake Systems, 5/e By James D. Halderman 11 Copyright © 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 • All rights reserved. FIGURE 4–12 The static coefficient of friction of an object at test is higher than the kinetic (dynamic) friction coefficient once in motion. Automotive Brake Systems, 5/e By James D. Halderman 12 Copyright © 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 • All rights reserved. FIGURE 4–13 Mechanical fade occurs when the brake drums become so hot that they expand away from the brake lining. Automotive Brake Systems, 5/e By James D. Halderman 13 Copyright © 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 • All rights reserved. FIGURE 4–14 Some heat increases the coefficient of friction but too much heat can cause it to drop off sharply. Automotive Brake Systems, 5/e By James D. Halderman 14 Copyright © 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 • All rights reserved. FIGURE 4–15 One cause of GAS brake fade occurs when the phenolic resin, a part of the friction material, gets so hot that it vaporizes. The vaporized gas from the disc brake pads gets between the rotor (disc) and the friction pad. Because the friction pad is no longer in contact with the rotor, no additional braking force is possible. Automotive Brake Systems, 5/e By James D. Halderman 15 Copyright © 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 • All rights reserved.