What is the Advantage of a Tag Axle for a Motor Home?by Charles Clay
A tag axle is a third axle located behind the rear drive axle of a motor home. It is a non-drive axle with one or two tires on each side. The main purpose of a tag axle is to increase the support of the chassis at the rear of the vehicle, allowing for greater carrying capacity and shock resistance.
Additional Carrying Capacity
A motor home with a tag axle will provide greater carrying capacity than a single-axle, generally resulting in a 10,000 to 20,000 pound increase. A tag-axle motor home will have a greater cargo carrying capacity than a single-axle motor home of similar size and power. Additionally, the addition of a tag axle allows for the construction of larger motor homes than single-axle designs, providing more space for the occupants.
Increased Rear Chassis Support
The tag axle provides greater support for the rear chassis, adding an extra set of shock absorbers and spreading the load across a larger section of the chassis. In addition, the tag axle is generally located farther to the rear of the chassis than a single axle, decreasing the leverage of the chassis extending past the rear axle. This reduces the likelihood of the rear chassis coming into contact with the ground when navigating steep inclines or uneven terrain.
Reduced U-Joint Wear
The addition of a tag axle pushes the drive axle further forward on the chassis. The engine of most motor homes is located behind and above the rear axle. The greater distance between the motor and the drive axle results in a shallower angle for the drive shaft, allowing it to create a more nearly level connection between the drive shaft and the drive axle. This reduces the strain on the U-joint, thereby reducing wear.
Additional Braking Power
While the tag axle is not connected to the motor, modern tag axles are often equipped with brakes. An additional braking axle greatly increases the traction and stopping distance for a motor home of equivalent weight. The ability to make sudden decelerations and stop more quickly is both a convenience to the driver and an important safety consideration.