An axle puller is a tool designed to remove an axle from an axle housing. Typically resembling a slide hammer or a dent puller, the axle puller attaches to the axle by bolting onto the wheel studs. The heavy hammer portion of the axle puller is pounded against the stop affixed to the end of the puller's center shaft, effectively forcing the axle and bearing assembly out of the axle housing. The puller can commonly be used in a reverse fashion to install a tight-fitting axle into an axle housing. The typical puller is easily disassembled to allow for easier storage when not in use.
There are several reasons that an axle might require removal with an axle puller, including stuck wheel bearings. Other reasons, such as a spline that is slightly twisted or burred, a bent axle or a broken axle, can all be the driving force behind an axle stuck inside of an axle housing. Due in part to the axle's design and placement within the wheel well of a vehicle, an axle puller is commonly the only tool that can be used effectively to remove an axle from the housing when it will not simply slide out of the axle housing.
Occasionally, even an axle puller is no match for a stuck axle. With an axle that is very old, rust or corrosion can build up inside the axle housing, creating a nearly impossible removal situation. Sometimes, only repeated pounding of the axle puller will coax a stuck axle free of the housing. In cases that involve a twisted spline, it may be necessary to attach a cable winch to the axle to force it out of the splines of the differential. Some versions of the puller use an over-sized slide hammer, which is designed to be used on severely stuck axles.
Occasionally, heat will need to be applied to the bearing cup area of the axle housing in conjunction with the axle puller to remove an axle from the housing. If, however, the cause of the binding is due to a problem within the differential, applying heat will not aid in pulling the axle. The typical puller attaches to the axle flange by three nuts fastened to three wheel studs. When encountering a severely stuck axle assembly, it is sometimes helpful to remove the axle puller and reattach it to different studs in order to apply force on a different area.