Central tire inflation system rotary air union

An apparatus configured for coupling to a hubcap and a hollow axle to place a fluid source in communication with a tire, the apparatus comprising:

• a rotary union assembly to couple to the hubcap of a vehicle, the rotary union assembly comprising:
• a housing to couple to the hubcap, a plurality of spokes formed with the housing and extending radially inwardly from the housing, a central hub coupled to the plurality of spokes, a stationary shaft coupled to and extending from the central hub in a direction toward the hollow axle, and a fluid flow passage extending through the stationary shaft into the central hub and through at least one of the plurality of spokes to an outer surface of the housing, wherein the housing of the rotary union assembly comprises at least one lubrication flow passage formed by the housing, the plurality of spokes, and the central hub wherein the lubrication flow passage is isolated from the fluid flow passage;
• an axle plug sized to cooperatively engage the hollow axle;
• and
• a flexible torque transfer shaft extending through the axle plug and engaged with the axle plug to prevent rotation therebetween, the flexible torque transfer shaft coupled to the stationary shaft and comprising:
• an air conduit having an upstream side and a downstream side, the downstream side in fluid communication with the fluid flow passage, and an elastomer overmold covering the air conduit and at least a portion of the stationary shaft, wherein the elastomer overmold resists rotation of the stationary shaft.

A vehicle having at least one wheel and a central tire inflation system comprising:

• a hubcap defining a lubrication cavity;
• a sight window defining a sight glass lubrication cavity, the sight window comprising a lubrication cavity vent;
• a rotary union assembly residing between and coupled to the hubcap and the sight window, the rotary union assembly having a housing defining an outer circumference and a plurality of spokes extending radially inward from the housing to a central hub, the rotary union comprising a plurality of lubrication flow passages formed by the housing, plurality of spokes, and central hub such that the lubrication cavity and the sight window lubrication cavity are in fluid communication;
• a flexible torque transfer shaft having a rotary union assembly side coupled to the rotary union assembly and an axle side opposite the rotary union assembly side, the flexible torque transfer shaft comprising an air conduit;
• an axle plug to cooperatively engage an axle of the vehicle and a bore sized to slidingly engage the flexible torque transfer shaft, wherein the axle plug is positioned between the rotary union assembly side and the axle side;
• and
• an air path is contained in the air conduit and the rotary union assembly to place an air source in fluid communication with a tire.

A vehicle having at least one wheel and a central tire inflation system comprising:

• a hubcap defining a lubrication cavity;
• a sight window defining a sight window lubrication cavity, the sight window comprising a lubrication cavity vent;
• a pressure monitor coupled to the hubcap;
• a rotary union assembly residing between and coupled to the hubcap and the sight window, the rotary union assembly having a housing defining an outer circumference and a plurality of spokes extending radially inward from the housing to a central hub, the rotary union comprising a plurality of lubrication flow passages formed by the housing, plurality of spokes, and central hub such that the lubrication cavity and the sight window lubrication cavity are in fluid communication;
• a flexible torque transfer shaft having a rotary union assembly side coupled to the rotary union assembly and an axle side opposite the rotary union assembly side, the flexible torque transfer shaft comprising an air conduit;
• an axle plug to cooperatively engage an axle of the vehicle and a bore sized to slidingly engage the flexible torque transfer shaft, wherein the axle plug is positioned between the rotary union assembly side and the axle side;
• and
• an air path is contained in the air conduit and the rotary union assembly to place an air source in fluid communication with a tire and the pressure monitor.