Abstract: A flow indication system for a central tire inflation system is provided. The flow indication system provides a venturi in fluid communication with the conduit providing air to a tire. A pressure reading is taken at the inlet and throat of the venturi and the air flowing through the venturi is calculated based on the pressure differential. According to some embodiments, the pressure readings are provided to a microcontroller that uses a table and interpolation algorithms to calculate the flow of the air flowing through the venturi, such as the mass of air in a given unit of time (grams/second for example). In one embodiment, two separate pressure sensors are coupled to different ends of a narrowed orifice that causes a pressure change in the flow as flow rate increases in the throat of the sensor.

Abstract: A central tire inflation system for maintaining tire inflation on a vehicle is provided. The central tire inflation system includes a rotary union assembly having a housing that is coupled to and rotates with the hubcap. The housing is rotationally coupled to a stationary shaft. A flexible torque transfer shaft is connected to the stationary shaft on one end and to an axle plug on the other end. The axle plug has a hub forming, a bore where the hub is movable on a web of material. The flexible torque transfer shaft and hub have cooperative non-circular shapes to resist rotation. An air vent is provided in the rotary union assembly that is isolated from the lubrication area, which inhibits the pressurized air from the central tire inflation system from pressurizing the lubrication area.