The Wheel bearings on the front axle consist of a pair of tapered roller bearings at each wheel, whereas the rear axle has a single ball bearing at each wheel. The front axle bearings are lubricated with grease applied at assembly, whereas the rear wheel bearing is sealed for life. The front bearing cups are easily removed with a drift such as a cold chisel, whereas the rear bearing needs to be removed with a 50 ton press at best, or a special tool can be used to screwpress the axle clear. As a last resort one can (with the backplate still attached) ram the bare axle down onto a hard surface to "shock" the bearing and coller off, but this method is a last resort!!!