A tandem axle trailer is a unit designed for hauling items behind a vehicle; this trailer will feature two axles to which at least four wheels can be mounted. The added axles and wheels provide stability and strength, and such trailers are usually used to haul heavy items. The style and function of a tandem axle trailer can vary significantly; some are enclosed units that protect the stored items from sunlight, rain, and other possibly damaging elements, while others are open-air models with back gates that can be lowered to create a loading ramp.
Connecting the trailer to a vehicle is accomplished by using a hitch receiver mounted on the vehicle and a hitch designed into the structure of the tandem axle trailer. Chains usually connect the trailer and vehicle as well to act as a back-up safety mechanism should the hitch system fail. A tandem axle trailer tends to be longer and heavier than single axle models, so the vehicle hauling the trailer will need to be strong enough to haul both the unloaded trailer and the loaded trailer. Larger vehicles such as SUVs and pickup trucks are best suited to the task, while smaller cars may not be able to haul the unit safely.
Like other types of trailers, the tandem axle trailer must be built properly in order to be street-legal. Brake lights need to be installed somewhere on the trailer, as does a mount for a license plate, and the axles, wheels, and tires will need to be of a certain size to be used safely on roads. The structure of the tandem axle trailer must be built in such a way that it is straight and balanced, preventing a loss of control when operating at higher speeds.
The two axles on the tandem axle trailer are usually unpowered, or passive, axles. These axles simply roll and do not provide any forward power or thrust to the system. All the power is provided by the towing vehicle instead, though some heavier trailers will feature braking systems to help slow down the unit during deceleration. In some areas, a braking system may be required for trailers of a certain size, so it is best to research local laws and regulations before purchasing a larger trailer. Laws may also dictate that items being towed in a trailer must be tied down or otherwise secured when being towed on roadways.