Properly serviced, quality heavy vehicle air spring suspensions will typically last hundreds of thousands of kilometres and give dependable cushioning service over years.
They offer top isolation of their cargo – and long-distance drivers’ comfort and anti-fatigue safety – by absorbing shock and vibration in even the roughest outback service, including mining, oil and gas, and supply of energy and exploration rigs to remote sites.
Having taken over the major market share for heavy rigid and articulated vehicles in Australia, air spring suspensions continue to expand in heavy vehicle vocational applications, such as dump trucks and heavy-haul tractors. Here too, they provide consistent ride quality in any load condition, which will help lessen driver fatigue while protecting equipment and chassis components from damaging vibration and road inputs..
Firestone Airide, one of the world’s top quality OEM and replacement brands, for example, will provide many millions of cycles of use over the roughest terrain, with just routine care and attention.
Air spring suspensions are increasingly penetrating vocational heavy vehicle markets also, including dump trucks and heavy haul tractors.“In fact, quality air springs are so exceptionally durable that they will often outlast other maintenance items on suspensions, such as bushings, shocks, leveling valves or regulators,” says Russell Chown, who has two decade’s experience specialising in heavy vehicle suspensions as Sales Manager with national Firestone distributor Air Springs Supply Pty Ltd
Russell Chown notes that air springs face exceptionally tough conditions here in Australia, which make quality, reliability, and service even more important.
“Fleet owners and individual operators are only too familiar with the roads to which our 365,000 rigid trucks over 4.5 tons and our articulated vehicles are subjected. Plus, service should be even more thorough to account for our long distances and the fact that our heavy vehicle fleet average age is more than 15 years, which is among the highest in the OECD.”
Many types of air Springs are found on heavy vehicles, including, at left, reversible sleeve types used on primary truck and trailer axles and in off-highway equipment and well as bus suspensions. Convoluted air springs, centre, are used as auxiliary tag lift truck and trailer axles. Cab, seat and steering axle sleeve types are shown at right.
Air springs provide rugged suspensions in off-highway equipment including resources site, materials handling, construction, and agricultural machineryRussell Chown says heavy vehicle owners and operators should be alert to the following common issues:
BOTTOMING OUT – indications of this problem include concave bead plate, internal bumper loose, hole in girdle hoop area (convoluted), hole in bead plate junction area or leaking around the blind nuts. Possible causes of the problems include broken or defective shock absorber; defective levelling valve; overloaded vehicle; pressure regulator set too low; wrong air spring (too tall).
ABRASION – indications include hole rubbed into the side of the bellow or hole in the bellows area where it rolls over the piston of reversible sleeve style air springs. Possible causes included structural interference, such as broken shock absorber, loose air line, misalignment and worn bushings. Further possible causes include no air pressure (reversible sleeve style), foreign material (and, rocks) and wrong air spring.
Over-extension trapped debris and age cracking are sometimes obvious to the naked eyeMISALIGNMENT – indications include off-centre bumper contact and similar symptoms to ABRASION AND BOTTOMING OUT. Possible causes include worn bushings and improper suspension installation.
LOOSE GIRDLE HOOP – indications include rubber bellows distorted and girdle hoop torn loose. Possible causes include running at extended positions with low air pressure.
CIRCUMFRENTIAL CUTS – indications include bellows cut in circle at bead plate junction or (in the case of reversible sleeve type) at piston junction. Possible causes include high pressure and full extension for extended periods, or impact in compressed piston.
OVER EXTENSION – indications include bead plate convex, especially around blind nuts or studs; bellows separated from bead plate; leaks at blind nuts or studs; leaking at end enclosure (reversible sleeve); loose girdle hoop on convoluted style. Possible causes include broker or wrong shock absorber; defective levelling valve; ride position too high; defective upper stop or wrong air spring (too short).
Preventive Maintenance checklist
“Before you install a new air spring, you should carefully examine the old one to see what caused it to fail. If it was due to a defect in the suspension system, then the new air spring may also fail unless you correct the problem,” says Russell Chown.
Checks take just a matter of minutes and will save both downtime and money across major users of heavy vehicles, ranging from transport and logistics fleets through to mining, construction, and individual users of articulated, rigid and on-road and off-road vehicles using air suspensions.
“Since each individual air spring is closely examined and pressure tested at the factory, the vast majority of premature failures and consequent warranty returns are found not to be defective, but fail because of abuse caused by other problems associated with the suspension,” says Russell Chown.
The following simple checks will pay dividends (noting that users should never attempt to actually service the air suspension on a truck or trailer with the air springs inflated).
- Where are air springs found? Firestone air springs can be found at a number of locations on the truck and trailer, including the primary suspension springs for the truck and trailer, auxiliary axles (such as a lift axle), as well as the cab suspension and often a front (steering axle) suspension. It is important to take note of all your air spring locations so that all of he locations receive proper maintenance.
- How often should I inspect my air springs? This depends somewhat on usage of the vehicle or trailer. The inspection could be based on frequency (such as quarterly or bi-annually), mileage (such as 80,000km 50,000 miles) or in conjunction with other suspension maintenance activities.
- What should I look for when I inspect my air springs? During your routine inspection of Firestone air springs take special note of any debris, cuts, deformities, or rubs that may lead to an imminent failure. If the air spring is damaged, replace it during this visual inspection process. If the air spring is damaged there is also a high probability that there may be other problems with the suspension, or other damaged components.
- Do air springs ever need to be cleaned? Once per year, when performing a thorough inspection, it is advised to clean the air spring with a soapy water or alcohol solution. This will help expose problems hidden from normal visual inspection. Soap bubbles may also help identify slow leaks that could be occurring, indicating a failing air spring. Do not expose air springs to open flames, solvents, or abrasives or else you may unintentionally damage the air spring, particularly the rubber. APPROVED: soap and water, methyl alcohol, ethyl alcohol and isopropyl alcohol NON-APPROVED: all organic solvents, open flames, abrasives, and direct pressurized steam cleaning
- Can I use an impact wrench to install my air bags? It is advised that an impact wrench is not used to install Firestone air bags. An impact wrench increases the danger of stripping the fittings off the bead plate. A torque table showing the installation force on various sizes of fasteners is available via a sticker on top of every new part and in our catalogues. It is important to follow these guidelines and use torque wrenches to achieve these recommended tightness values. It is important to check the tightness of all mounting hardware (nuts and bolts), if loose re-torque to manufacturer’s specifications-do not over tighten
- Inspect the O.D. (Outside Diameter) of the air spring. Check for signs of irregular wear or heat cracking.
- Inspect air lines to make sure contact doesn’t exist between the air line and the O.D. of the air spring. Air lines can rub a hole in an air spring quickly.
- Check to see that there is sufficient clearance around the complete circumference of the air spring while at its maximum diameter.
- Inspect the O.D. of the piston for build-up of foreign materials. (On a reversible sleeve style air spring, the piston is the bottom component of the air spring.)
- Correct ride height should be maintained. All vehicles with air springs have a specified ride height established by the O.E.M. manufacturer. This height, which is found in your service manual, should be maintained within 6-7mm (1/4”). This dimension can be checked with the vehicle loaded or empty.
- Levelling valves (or height control valves) play a large part in ensuring that the total air spring system works as required. Clean, inspect and replace, if necessary.
- Make sure you have the proper shock absorbers and check for leaking hydraulic oil and worn or broken end connectors. If a broken shock is found, replace it immediately. The shock absorber will normally limit the rebound of an air spring and keep it from overextending.
Russell Chown says Air Springs’ national distribution network – built up over more than 40 years – has been on hand throughout the entire pandemic and subsequent supply chain shortages to supply air springs and back up with technical advice from its large, modern HQ in Sydney and through its distribution network in every State and Territory.
Its world-class Airide, Airstroke and Airmount ranges – distributed across the US, Europe, Asia, and Australia – may also cross over with other air spring actuators incorporated globally by OEM manufacturers of equipment used in industries. This can help individuals and fleet owners who cannot get supply of a particular type of spring for which there is a crossover alternative from Air Springs Supply.
“We have 40 years of experience backed by a national network geared to assisting them source alternatives to minimise disruption, because truck operators cannot afford to be off road for long,” says Russell Chown.
Firestone Airide specialises in air spring manufacturing and technology, with a history of more than 80 years of research and development on technologically advanced air springs for the global marketplace.