US Patent 7373811 Tire filler with pressure indicator

A combination valve stem extension hose and pressure indicator is disclosed. The extension is threaded onto a standard valve stem. The extension tube is available in a variety of lengths to accommodate filling inside dually tires. The extension tube also is available with various bend angles. A pressure indicating piston is provided to give visual status of the pressure within the tire in a static filled condition and while air is being added to the tire. The construction of the pressure indicator allows for threading or welding of the sight glass. Improvements in the pressure indicator include locating, aligning and positioning features to improve operation and longevity of the gauge.