Design of an Emergency Tire Inflation System for Long Haul Trucks

An Emergency Tire Inflation System (ETIS) designed for use on commercial trucks was evaluated and tested. The ETIS is provided in kit form and designed to be installed by a truck operator to provide emergency air to inflate a low or punctured tire on tractor drive axles. The ETIS will continue to supply air to the tire until the system pressure falls below a safe air pressure level. The system is designed to allow the rig to be driven 500 miles to a tire repair station or to a safe location where tire repair service is available. The installation kit (Figure 1), which can fit under a truck seat, includes all the necessary equipment to install the system on the most common drive axles.

The ETIS supplies air to the under-inflated tire through a previously qualified¹ Rotary Union design. The Rotary Union is attached to the axle flange of the drive axle by a threaded adapter and two adjustable links that allow the Rotary Union to be placed at the center of rotation of the axle. A Glad Hand Assembly with a built-in pressure regulator is installed at the trailer. A sufficient length of coiled nylon tubing meeting the requirements of SAE J514 is provided in the ETIS kit to provide emergency air to the most distant drive axle tire.