What is a tri-axle?
A tri-axle vehicle is a truck, tractor, or trailer with three axles grouped together at the rear. Tri-axle vehicles are primarily used to haul heavy loads. The multiple axles and wheels allow for better weight displacement and stability. Dump trucks, tow trucks, and cement mixers usually have a tri-axle design.
The most common tri-axle configuration includes a tandem axle with an air-lifted third axle. In this design, truck drivers can move the lift axle up and down via in-cab controls, so the tires aren’t on the ground if the truck isn’t loaded. Lifting the extra tires in the air when the truck is empty helps save on tire wear and fuel consumption.
When it comes to lift axles, state laws and overall weight capacities may vary, so interstate operators need to understand regulations in their surrounding areas. Some states don’t allow lift axles. They must be kept elevated, significantly lowering how much a driver can carry across state lines.
Tri-axle trailers
Tri-axle configurations are also used for heavy capacity trailers. For instance, because heavy equipment used in construction cannot operate on public roads, high-capacity flatbed trailers must tow them to job sites.
Tri-axle trailers connect to a truck or tractor via a gooseneck hitch or fifth-wheel hitch. (Or connect a gooseneck trailer to a fifth-wheel hitch with a kingpin coupler.)
What’s the difference between a tri-axle and a quad-axle?
When researching tri-axle commercial vehicles, you may come across quad-axle axles vehicles as well. What’s the difference between these types of vehicles?
Tri-axle configurations
Tri-axle configurations are smaller and more lightweight. While that may translate to lower tolls and costs, they also have lower maximum operating weights. In trucking, tri-axles are commonly used for local hauling and construction work. For example, a tri-axle dump truck has better maneuverability in smaller spaces than quad-axle dump trucks.
Quad-axle configurations
Quad-axle vehicles usually have two-powered and two-unpowered axles. Quad configurations can support heavier payloads and generally cost more to maintain. Even though they have higher costs, they’re a better choice for longer hauls and interstate transportation. Due to their size, they aren’t recommended for construction sites where maneuverability is tight.
