Document B53kL7Eexv2DZd7BNXyxLDR5w

combinations. Eight weight classes currently exist, although for the purposes of this study, the following classifications are used: Classification Light Medium Heavy GW Class Group 1 Group 2 Group 3 Group 4 6roup 5 Group 6 Group 7 Group 8 GVW Range fibs) 6,000 and less 6,001 and 10,000 10,001 - 14,000 14,001 - 16,000 16,001 - 19,500 19,501 - 26,000 26,001 - 33,000 33,001 - over New truck registrations for 1984 indicate that light trucks make up approximately 94 percent of the total truck population, which reflects the popularity of small pick-up trucks and mini vans. In contrast; medium trucks account for about 1 percent of the population, while heavy trucks make up the remaining 5 percent(^). The following sections outline current brake systems and trends in vehicle brake materials for the three classes o.f on-highway trucks. 5.2.2.1 Light Trucks. The "light truck" designation refers to both pick-up trucks and compact vans used in light hauling and passenger transport. About 3.9 million light trucks were sold in 1984 in the U.S. As of 1984, almost 31 million light trucks were registered in the United States. Trends in light truck braking systems follow closely those of passenger cars. In 1984, more than 94 percent of light trucks manufactured in the United States were equipped with front wheel disc brakes. Ford and GN 1987 light trucks are using variable proportioning valves for rear brakes or anti-lock systems to Improve braking under a wide range of truck loads. Calibration of a variable proportioning valve is affected by changes in rear brake lining material. In this respect, trucks brakes are following European passenger car trends in that design steps are being taken to ensure front wheel brake biasing. 77