Rotary union assembly for use in air pressure inflation systems for tractor trailer tires

摘要

A rotary union assembly for use in an automatic tire inflation system for maintaining the desired pressure in the tires on a tractor trailer or other vehicle having pressurized axles. The assembly communicates the valve stems on a pair of adjacent tires with the axle interior through the use of a flexible tube extending between a stationary first fitting threadably engaged in the axle spindle and a rotary housing secured against the outside end surface of the hub cap so as to be positioned exteriorly of the wheel lubrication compartment and rotatable with the hub cap. The first fitting defines an open channel extending axially therethrough and includes an o-ring seal extending about the channel and forming an airtight seal within the fitting about the tube. A stationary shaft member having an air passageway extending axially therethrough carries the downstream end of the flexible tube and projects into the rotatable housing to communicate the axle interior with the housing through the flexible tube and provide a rotatable mounting for the housing on the shaft. The shaft defines a stationary bearing surface on its downstream end. A rotary sealing member having an air passageway extending axially therethrough is mounted within the housing for rotation therewith. The rotary sealing member defines a rotary bearing surface which is urged the stationary bearing surface on the shaft member by a spring member. Opposed channels are provided in the housing proximate the bearing surfaces and hose and valve assemblies communicate the opposed channels with the tire valve stems.