Today, most truck purchasers specify an air dryer on their new vehicles. There are a variety of product options currently available for drying and cleaning compressed air on trucks, buses, and other vehicles. Clean, dry air has become increasingly important on trucks for the operation of brakes, suspensions, fan clutches, seats, and other components. High air use vehicles, such as bulk haulers, are applications that demand new technologies to solve difficult air system problems.A number of methods can aide in the removal of water and other contaminants from compressed air systems. These methods include: aftercooling, filtration, desiccant adsorption, coalescing, centrifugal force, or some combination of these processes. Effective elimination of contaminants from the system takes additional processes. For instance, dryers which include desiccant must have sufficient purge volume and control systems to regenerate the desiccant material for optimal performance. Working together, the right combination of these and other drying processes will provide maximum contaminant removal.Is there one configuration of these processes that provides optimum performance for all vehicle applications? Definitely not. However, all applications have similar contaminants in the air which should be removed. Once separated from the air, the concern becomes getting those contaminants out of the dryer so it can continue to function properly. Removal of contaminants and regeneration of system components is where the major differences lie between the specific processes needed for each vehicle application.