Air springs will last almost indefinitely in most applications as long as you follow an air springs inspection guide to ensure their longevity.
They fail quickly when rubbed, scuffed, or punctured. If an air spring fails, the trailer will settle on the internal rubber bumpers, allowing the driver to safely proceed to the nearest service facility at a lower speed.
Close inspection of air springs is often neglected because of their normally long and trouble free service life. To avoid unexpected failure, it is important to check and correct any issues during service.
Using an Air Springs Inspection Guide
Look for chafing or any signs of component damage. Look for misplaced air lines that may rub on air spring bellows. Check to ensure truck or trailer ride height is at specification. Operating at an incorrect ride height will place extra strain on air springs, shock absorbers, axle restrain limiters and bump stops.
Ensure that the upper bead plate is tight against the underside of the frame and that the mountings show no sign of movement. Air springs should be cleaned regularly, removing dirt and dust that may build up around the bead. Any grime in this area will eventually wear through the rubber bellows and cause premature failure to occur.
Air springs can be ripped apart if axle movement is not restrained by an axle restraint system, such as shock absorbers, chains or straps. Therefore, shock absorbers, restraints and mountings should be inspected for cracking and for serviceable condition. Replace all worn or damaged air spring or shock absorber components.
Air Springs Inspection Guide in Skel and Tipper Applications
When tippers are raised for tipping it is advisable that the air suspension is dumped of all air from the system. This is to increase stability when the centre of gravity is raised as the load is raised. Also, if the air springs are pressurised when the load is released suddenly; then the air springs will extend forcefully and put extreme loads on the shock absorbers and mounts. For this reason, container skels, and similar applications where loads are removed suddenly, should also be dumped of air prior to removal of the load.
When air suspensions are fitted to tip over axle tippers a pressure retention system should be fitted to the air suspension layout. The purpose of this system is to retain some residual pressure in the air springs so that the air spring bellows do not become caught between the piston and plate, where they may get damaged as the axle lowers back to the ground.
It is important to not simply add a pressure valve to the exhaust port on most height control valves. Adding a pressure retention valve to the exhaust port will inhibit valve operation and will not retain any pressure in the air springs when dumped. This is because many valves, such as Haldex, dump through a port in the body and not through the exhaust port that is used for height control. A system to retain some air spring pressure regardless of height control valve operation, such as a Hendrickson AK-136, should be installed between the air springs and height control valve.