There are two types of ATV axle which can be used on all-terrain vehicles (ATVs): the half-shaft axle used in independent axle applications, and the solid axle used on the more common straight axle design. The ATV axle is used to not only attach the drive wheels and tires onto the machine, but to power the ATV as well. Whether extending out from a differential in independent suspension models or holding the rear sprocket on straight axle versions, the ATV axle is an integral component of an ATV suspension and drive train. The solid axle design typically uses bearings only on the center section of the axle as it passes through the rear swing arm, while a half-shaft axle uses constant velocity (CV) joints on each end of the half axle to allow for bind-free axle articulation.
Due to the tremendous amounts of power produced by the engines as well as the very high loads placed upon the ATV axle as it is slid into corners and driven up steep rocky terrain, the axle is often one of the first components to break on an ATV. In an independent suspension design, the CV joints are typically the first component to break under the pressure of rough riding conditions. On a solid ATV axle application, the axle is usually bent due to contact with a rock or similar object as the rider slides the machine around a corner or negotiates very rough terrain.
Fortunately, the average ATV axle is not very difficult to remove and replace with only ordinary hand tools and a minimum of skill required to do so. It is a common practice to replace the bearings any time an ATV axle is replaced due to the bearing's location on the axle and the requirement to remove the axle to perform the bearing change. This may save valuable time by eliminating the need to change the bearing at another time. When it comes to the CV joint on a half axle, changing both ends at once is the preferred method of servicing this component.
A common trait of the majority of ATV models suffering ATV axle failure is the application of over-sized aftermarket wheels and tires. The large rolling stock gives an enhanced appearance to the ATV, however, the ATV axle is not designed to tolerate the added load and torque. This stress placed on the drive train by the new larger wheels and tires can quickly damage an axle.