I may have this figured out, but then again.....
I think the inner wheel in the Stud Piloted system on Brad's coach is held in place with what is called appropriately enough a "Inner Cap Nut". The second image I have attached shows one.
At some later time Newell starting using axles that were hub piloted. In other words, the wheel is held in its exact position by the machined surfaces on the hub that exactly fit the bore of the wheel. You can also recognize this type system by the flat washer under the nut holding the wheel on. The first image is of my rear drive axle and you can clearly see the washer and the machined mounting surface for the wheel.
Now with the stud piloted, the nut goes into a spherical depression in the wheel and centers the wheel based on the position of the studs. It is that type arrangement that uses the inner cap nut.
I found the following two narratives which you may find both amusing and informative. I'll just keep my road service plan in force.
We run the 22.5" tires on the FL-60. Budd style lug nut set up and cones as described above. As I mentioned previously we have had to pull our own duallies a couple of times. Minimum tools we use for this: 3/4" drive extension, sockets, and breaker bar. Really long piece of pipe, 10 ton bottle jack, floor jack, wood cribbing, advil, bottle of whiskey. Preferred tools: jack, 1" drive, sockets, torque multiplier, extension, breaker bar, advil, whiskey, cigar. Kroil or another good penetrating oil.
General Instructions for Minimum Tools:
Squirt the lug nut down with Kroil or another good penetrating oil. Block the axles front and back to prevent the truck from rolling. Fit the socket and extension up to the lug nut. Attach the breaker bar and cheater pipe - you will now note that the end of the 3/4" extension where it connects to the breaker bar is not supported. Put the floor jack head under this end of the breaker bar. Put the cheater pipe over the end of the breaker bar - total length of the breaker bar and cheater pipe must produce close to 1000 ft-lbs of torque to break the lug nut free if you have aluminum rims. Apply necessary force - be careful the lug nut will release with the sound of a .243 / 30-06. I weigh 165 lbs and typically have to put all of my weight on the end of a 6' long set up to break the lug nuts free. After 5 or 6 of these are broke free, one of the neighbors will have called the police - reporting possible gunshots. The cop will be greatly amused since it is not gunfire. . . . but he/she will not offer to help. Once you have all of the lug nuts broke loose, jack the axle up and block with the wood cribbing - cement blocks will not work, they will crumble under the weight of the axle - but only after both tires are off. Carefully remove the lug nut the rest of the way. You will note that the tire is very big and heavy - even with aluminum rims. Without a tire donkey it can be a challenge to pull the tire over the stems without damaging threads - good luck on your approach and ingenuity. Repeat this process for the inside rim.
On reassembly, luricate the threads with anti-seize if you are not going to be in any area where road salt or Mag Chloride is used. Otherwise use a penetrating oil. The anti-seize is typically made up of nickel, copper, silver, or some combination of these and since they are much more Noble than mild steel or aluminum the anti-seize could cause the wheel studs and wheels to pit / corrode when road de-icing salts are used. I would not use a graphite based anti-seize in this application.
Good luck!
This from an article written in '99 - so newer would refer from that time.
WHEELS: MAKE SURE THINGS MATCH
RoadStar
August 1999
Every time you do a circle check, inspect every wheel for damage. You’re looking for cracks in the structure of the wheel, rust streaks away from the lugnuts or broken and missing studs.
If a stud is broken, replace it as soon as possible and preferably before leaving the terminal or truckstop if you can. But don’t skimp on the repair. The correct procedure is to replace the studs on either side of the broken one at the same time. The loading on the remaining studs may well have exceeded their design limit, and a catastrophic failure with the loss of a wheel could result. Wheels are two basic different types these days, the older Budd-type that are stud-located and hub-piloted wheels.
Stud-located wheels are identified by their inner and outer cap nuts on dual pairs, with left- and right-hand threads on either side of the truck or trailer.
If the wheels are stud-located with a ball nut in a seat on the wheel, try to ensure all studs and inner and outer cap nuts are Grade 8. And be careful of counterfeit hardware. If you are looking for Grade 8 ball and seat nuts, there’s a Euclid E-5977-L/R for left or right thread.
Hub-piloted wheels are increasingly common now, but there are still many older trucks and especially trailers running around on the stud-piloted wheels with the ball-seat nuts.
The wheels may be the same size and have the same number of stud holes, but they are definitely not interchangeable, either on the hubs or in the use of hardware.
The hub-piloted wheel is located on lands carefully machined out of lugs cast into the hub.
These machined lands center the wheel, and flat-faced lug nuts with integral washers clamp the wheel to the hub face. When mounting hub-piloted wheels, try to “hang” the wheel from one of the machined lands located at the 12 o’clock position. This will more closely center the wheel for optimum balance and minimum runout.
The older-style wheel uses the spherical seat and matching radius on the nut to locate the wheel, as well as to clamp it to the hub.
Do not mix the two systems even in an emergency. In neither case will the hardware clamp the other type of wheel adequately to the hub face if the wrong hardware is used. Studs can break, wheels move and the whole assembly may separate with potentially disastrous results.
Know what you are dealing with by looking at the pilot hole and the stud holes in the wheels if you are in any doubt.
During the walkaround or in a more detailed inspection, any streaks or cracks you may find in truck wheels signify a problem. Knowing how to read the cracks can tell you about the problem.
First streaks: These rusty marks coming radially away from a lugnut indicate a loose fastener. The answer is to get a torque wrench on to it immediately. Step 2 is to try and think of reasons why the lug nut might have loosened.
Cracks that run from stud hole to stud hole arise when a wheel is loose or incorrectly torqued. A regular maintenance program that includes checking lugnuts with a torque-wrench should go a long way to eliminating this cracking. But include regular removal of the wheels to clean the mating faces and then torquing down the lug nuts.
Cracks that run from stud hole to hand-hole, hand-hole to rim or hand-hole to hand-hole are caused by overloading. The cure for this should be obvious.
Cracks that run around the disc nave indicate a bad fit-up, or a damaged hub that is placing alternating stresses into the wheel center. They can also indicate overload. When servicing the wheelends with the wheels off, clean any rust from the mating wheel and hub surfaces.
Check the hub for distress and ensure there’s no damage at the stud holes or wear on the wheel mounting face. And never weld a damaged hub. If it’s a bad hub, replacement is in order.
Cracks in the rim base are probably the result of poor handling during tire mounting, where deep tool marks have produced stress-risers in the rim. The cycling of the metal with each revolution of the wheel leads to these fatigue cracks. However, these cracks can also be caused by overloading and overinflating tires or using larger-than-recommended tires for the rim to compensate.
Forged aluminum wheels — besides looking more attractive — deal much better with overload, poor handling and stress. But don’t be tempted to switch from a steel front wheel to an aluminum one without checking the length of the studs. Make sure the lug nuts have sufficient thread overlap to bear the clamp load. Stud threads should project above the nut at least a third of the height of the nut for adequate clamping.
And finally, here is a link to a good explanation of the two systems:
http://orrcointernational.com/technical_wheels.php
May your studs not break and your nuts not crack....
