US Patent 7338550 Axle assembly with purge reservoir for air dryer

An axle assembly includes an axle beam with an inner cavity that forms a purge reservoir. The purge reservoir is fluidly connected to an air dryer with a purge valve. The air dryer is part of a vehicle air supply system that supplies air from a compressor to storage reservoirs for vehicle systems such as suspension and braking systems. The air dryer includes a desiccant material that removes moisture from compressed air. During a compression cycle, air flows through the air dryer to the storage reservoirs and to the purge reservoir. Once a desired pressure level in the storage reservoirs is achieved, the compressor is unloaded and a purge command is generated to open the purge valve. When the purge valve is opened, air stored within the purge reservoir flows back through the air dryer to regenerate the desiccant material.