When it comes to heavy-duty commercial vehicle components, so many have vital roles, and this includes lift axles. Serving as the backbone of state and federal road and bridge protection, lift axles serve a crucial function. Still, as is with so many other complex debates within the trucking industry, a byzantine maze of regulatory requirements clouds the lift axle picture.
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For many, understanding what their state’s requirements are can be an exercise in futility. What you need is a comprehensive guide to get you through the rules landscape. But first, let’s take a closer look at what exactly lift axles are and the function they serve.
The Lift Axle: A Brief History
The first thing to know is that lift axles are non-powered. During use in their primary function, they can be lifted completely clear of the surface of the road. Additionally, they can be lowered, specifically to shoulder the burden during use with a straight truck or tractor-trailer.
You may also have heard of a lift axle being referred to as “auxiliary” or “retractable.” Lift axles haven’t always been the hot item on the street. Back when mixed-use vehicles such as dump trucks and concrete mixers began to go into mass production, lift axles entered wide-spread use.
A lift axles primary purposes include serving a role in ensuring the vehicle meets regulatory standards and distributing the weight evenly, thus making sure single axles and tandems never bow under the strain of too much weight.
The primary motivation for specific lift axle regulation was born out of the need to meet federal bridge law standards. The problem is that most states have their own regulations regarding lift axles, while the federal government still has their own sets.
How Do They Work?
In typical applications, a lift axle utilizes air bags, springs, or combination of both. The action is intended to lift and/or lower a set of wheels. While the application is sometimes used on tractors, lift axles are more commonly employed under a straight truck or trailer.
The truck driver operates the lift axle via a set of controls in the cab. They are either electrical or they could be air valves. In some cases, they are installed outside of the cab, depending on the application.
There are three distinct versions of lift axles:
- PUSHERS: These lift axles are installed to the fore of the rear tandem axle. They are used to extend the truck or tractor’s overall wheelbase.
- TAGS: These are air systems installed to control the lift and lowering of the auxiliary axle. Control valves are used to regulate the amount of air stores in reservoirs.
- STINGERS: Tags are most commonly used on concrete mixers and dump trucks. They are a hinged, dual swing-arm system that swings, engages and disengages a lower and upper axle to activate the swing-arm
There are also steerable and non-steerable lift axles. Steerable lift axles have two modes of operation. One is designed for use when the axle needs to be left down when the vehicle is moving in reverse.
Steerable lift axles have to meet specific regulatory standards to meet manufacturing requirements. Due to their complex nature, steerable lift axles are generally more expensive than their non-steerable counterparts.
Non-steerable lift axles are simply that, non-steerable. They always follow the vehicle or the trailer. One can expect far less wandering when using a non-steerable lift axle.
Whichever you choose to go with, remember that lift axle requirements vary depending on the state that you live in. One example of a law you might need to know is that in New York, lift axle controls must be located outside the cab.
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Whatever the application, ensure you are complying with all lift axle regulations. Only through full compliance can you ensure safety and minimal fuss when it comes to inspection time.