I've personally done the press work on over 100 Explorer rear wheel bearing/hub replacements. I am from Minnesota so we deal with many that are quite rusty. Never needed more than a 20 ton press (which is what we had at our shop) to do the disassembly/reassembly of any unit.
Some notes on the process:
The hub is pressed out to the outer side of the knuckle, and then the bearing (or what's left of it) is pressed out to the inside of the knuckle assembly. There is a large snap ring holding the bearing in the knuckle. Remove this before attempting to press the bearing out. I never used snapring pliers on these, I started on one side with an awl and two flat bladed screwdrivers, working my way around until the entire ring was removed.
The bearing will be destroyed when pressing out the hub, the outer-most inner race will come with the hub and is notoriously difficult to get off with a press as most bearing sharks will not grab the shallow groove in the race. I normally used a large chisel and hammer to create a gap between the race and hub, allowing room for a shark to be used behind the base of the race. If you use a cutoff wheel make sure not to damage the hub, and if you use heat you can cause other problems, so do your best to use tools and avoid heat.
If the hub surface where the inner race is pressed on has become corroded, blue/black with becoming overheated, or the bearing spun and created a groove the hub must be replaced, otherwise reusing the old hub is fine.
When removing the (rest) of the bearing from the knuckle assembly it is *very* important to properly support the knuckle so that your plane across the bearing circumference is near exactly 90 degrees perpendicular to the direction of force you will be applying (with the press ram). This will be equally important on reassembly, and is an order of magnitude more difficult as the outer face does not sit nice and flat by itself. Take your time in setting up your press table and knuckle assembly. This is very important, as the forces at work to do this job are immense.
It is important *where* you are applying force and *what* you are supporting when doing the presswork when dealing with the new bearing installation. You must *only* apply force to the outer race when installing the bearing into the knuckle (use the old outer race on top of the new one). When pressing the knuckle and bearing down onto the hub you must apply the force to the *inner* race area to properly seat it.
Once it is reassembled (don't forget to reinstall the snapring!) reinstall on the vehicle paying special attention to torque specs for the axle nut, and use a properly set torque wrench.
Some final notes on just going out and buying a press...you will likely not have enough sturdy things laying around of the proper size to press on the appropriate areas you will need to apply force to. There is more to using a press properly than *just* the press itself. Adapters, old bearings or seal drivers, rings made of steel of various sizes, varying thickness steel plates to prop on, etc. are necessary to do the job safely.
I hope some of this information helps you or someone else researching this topic.
