Spread Axle Trailer Designs
Many trailer manufacturers are offering several models with spread axle designs due to customer demand. End-users report a number of benefits to these designs both functionally and cosmetically. For example, many owners believe that a trailer with a spread axle design “holds” the road better and improves the trailering experience. The spread axles disperse the load
across the trailer better and help improve tire life longevity while also cutting down on trailer sway and wag.
Most spread axle designs include setups with torsion axles that provide a ride that offers independent suspension at each tire. Depending on the model and the overall engineering design of the trailer, some trailer manufacturers choose to spread the axles out at different distances. Longer trailers often produce an improved ride if their axles are spread at a greater distance compared to shorter trailer models.
End-users enjoy the cosmetic characteristics that spread axle designs tend to offer. These improvements include chrome or stainless steel skirting with non-traditional lines, thicker bottom trims, and drop down perimeter skirting, including the area closest to the tires. Many customers also prefer the lines offered from the side view of some of these models where the body and walls of the trailer dip down gradually toward the ground before the front axle, and stay down for a short distance after the rearmost axle, before gradually tapering back up for ground clearance near the rear end of the trailer.
Other popular options include different rim and tire configurations such as 16-inch tires that nicely fill out fender wells, and custom wheels in chrome and black. Axle manufacturers offer torsion axles in several sizes, some of the more popular torsion axles utilized in these designs are the 3,500 lbs, the 5,200 lbs, and the 6,000 lbs options.
The spread axle design also allows for additional accessories, such as the installation of a step between the two axles. This step can then be used when exiting the trailer from the side via a side door. After the back axle, some manufacturers' designs have the rear end of the trailer tilt up to prevent the rear of the trailer from dragging on the ground in uneven terrain. Skid plates are a popular option installed to avoid damage in the event the rear of the trailer does come into contact with the ground.
However, traditional axle placement is still very popular in the light- and medium-duty trailer industry. There are many reasons why trailer manufacturers would stay with a traditional axle placement designs on their models.
One of the main reasons for not spreading axles is that spreading them may not be the best trailer design for the intended use of the trailer. Engineers and designers may prefer to keep the axle placement tighter. Depending on the intended cargo, many dual and triple axle trailers including tank trailers, generator trailers, boat trailers, dump trailers, and equipment trailers may handle better and be better suited overall for traditional axle placement. The decision is up to each trailer manufacturer, and they must take axle placement into consideration when they design a model as part of the overall analysis including determining each trailer’s Gross Axle Weight Rating (GAWR), Gross Vehicle Weight Rating (GVWR), cargo capacity, and shipping weight.
For a list of NATM Associate Members that sell axles or engineering firms that specialize in designs and testing, visit the online NATM Membership Directory & Buyers Guide at www.NATM.com.