The shrink fit of driver tires on centers is the primary means of holding the tires in place. However I have also seen that most tires have a lip that prevents the tire from sliding inward, and some have grooves with retaining clips bolted or riveted to the center which keeps the tire in place.

How crucial are retaining rings or clips to holding the tires in place? I ask because we are considering sliding the 33" tires on the 58 out 1/2" to go from 23" gauge to 24" gauge. I do not know if our tires even have the retaining lip, but if they do they would not be effective after moving the tires.

Thanks!

There were many ways of doing more than just shrinking tires on. Gobson Rings for example.... which I only know about because when some Australian friends were starting tom work on restoring a Baldwin, it didn't have any so they wanted me to tell them how to install them. Not necessary, Mate.

Anyhow, you don't need to move the tires. She'll run just fine on 24" track, 60CM track, or 23" but on tight curves around the steel mill she'll like the 24" gauge much better. You just want to tighten up the track geometry on the switches so there's no extra tolerance around the frogs and guardrails.

That extra half inch per side shouldn't make much difference at all when it comes to running, but it would be a huge reduction in surface area for the shrink fit holding the tires on. No point "reinventing the wheel".

You're not likely to be running the locomotive fast enough to encounter problems with severe hunting, etc.

A slight gauge change like this could rapidly become a huge engineering challenge with very little reward.

Steve Hunter

The problem with not moving the tires out is that the guard rails in switches can pull the axle over far enough for the opposite tire to hit the frog points pretty hard. If you don't have switches or diamonds then it shouldn't be an issue. On the other hand it isn't that hard to move the tires out. On the three of the four engines I have done tire work on it is only the shrink that secures the tire to the driving center. The significant dimension that you need to target is the back to back. That is the dimension between the inside surface (the back of the tire) of the two tires. I don't know what that dimension is however I think there are several persons who follow this blog that cold provide it.

There is a great satisfaction in doing this kind of work and if for no other reason then the experience I suggest you do it.

CCdW

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If this engine is like my porter, there will be no lip, just a shrink fit. Others I have spoken with have also seen this on porter wheel centers. So it is likely that no problems would be encountered with sliding the tires out so long as the rims did not interfere with the rods, xheads, guides, etc. and I second what Chris said, doing for the sake of learning and knowing is reward enough sometimes.

I have seen several different wheel profiles and back to back dimensions for different industrial goats - I wouldn't make any assumptions about this one. I have no Porter S&P book to consult. I don't think it's worth the risk of having a loosened tire to move them out just so you can say you did. If the wheel center visible diameter inside is the same as outside, you have no lip. If it is bigger, you do. if it is smaller, you have other problems.

Steel mill track was not laid with a micrometer, but with a bar of metal with two wide worn slots torched into it. Don't overthink yourself into unnecessary problems. If you find a switch has a point that bumps, grind it to where it makes a smooth transition. It's supposed to be rough, ready and dirty and dinged.

Or just do the reverse of what they did with the Russian Decapods, wide tires.

-Hudson

I wonder if the clips just served as a positioning guide until the wheel cooled and the shrink fit took hold? That would be a good way to handle that assembly, by making the parts "self-jigging."

Sure, the clips could absorb the loads developed by the flanges, but maybe that is just a coincidence?

Disclaimer: Just my two cents, I built a 7-1/2 gauge live steam Porter, but its wheels are just solid cast iron.

This statement is backwards. The problem with narrow wheelsets is that the guard rail will pull the wheel over, and the back of its mate will hit the wing rail, not the frog point. The easiest solution is to move the guard rail in. That, of course, may let the wheels on the cars pick the frog point, but in reality. wheels usually will run through frogs from force of habit. Anyway, we have no idea if the wheels on the cars are full profile, or the narrow industrial cart wheels with abbreviated flanges. Trust me, I had more than my share of nursing CSL narrow tread, narrow flange tram wheels through AREA track years ago.

Also, keep in mind that there is considerable clearance between the flanges and the gauge face of the rail; the wheel is supposed to run on the fillet, not the flange. Rick could probably build the track to 23.5" gauge and the cars will run just fine.

If I was Rick, I'd leave well enough alone. Build the turnouts without guard rails; only add them if needed. Attach the guard rails with through bolts and a pile of washers for spacers, making it easy to adjust their spacing as needed.

The current back to back distance is 20 1/8", with a 5 1/2" wheel width. The cars that I would like to use are the Carpenter Steel cars that Kovalchick has, because they are readily available. They have a back to back distance of 21 1/2" with a 3 3/4" wheel width. So a problem is that if I set my guard rails to clear the locomotive drivers, the guard rails will not be very effective with the cars and their narrow wheels.

If I move the tires out I will have a 21 1/8" back to back, which is still 3/8" wider than the cars but close enough so that the guard rails would be effective. As Kelly says it is easier to adjust the locomotive now and develop a set of standards now rather than modify everything else to fit later on.

I haven't taken my big calipers over there yet to see if I can determine if the outer ID of the tires are smaller than the inner ID of the tires. The tires already overhang the inside face of the centers by about 1/4", and the centers stick out about 2" on the outside.

With that much driving center available by all means, move the tire. Of course check diameters and clean the driving centers well where you plan to relocate the tire to. Be aware that there is a high and low value for the back to back. Aim for the median. Ask if there is a fire ring of the correct size for your tire that you can borrow and go for it. The smallest I have is 42" and its in the west . Someone in your neck of the woods should have one so ask around. Also be aware that there is a provision for shimming the fit of tires on driving center so you may encounter shims when you go to work or you may need to add shims. You will need to block the engine up off the ground so there is no weight on the tire. Once you are set up you should be able to complete the job in an afternoon and be back on the ground shortly there after.

Good luck.

CCdW

Where I worked before I retired we had a large fleet of tired wheels. The tires had a lip on the outside and a groove for a ring on the inside. These retaining devices were there to keep the tire on the center in case the tire was heated due to breaking, slipping or sliding. There was usually a lot of corrosion between the center and tire when they were removed. The tires were removed by cutting them most of the way through. With about an 1/8" inch of tire left, it would break releasing the center. Centers were turned just enough to clean off the corrosion. Tires were bored for a fit of 0.001" per inch of center diameter. Tires were heated to 400 to 500 degrees to expand them to get them on the centers. The best tire heater I ever saw was at ORX where they used an induction heater to heat the tire. The tire was clamped to the center until it cooled. Then the retaining ring was installed. The wheel assemblies were always pressed on and off the axle with the tires installed.

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There is a potentially useful and interesting discussion of Gibson ring fitting on the South Devon site:

http://www.southdevonrailwayassociation ... g_Sep.html

(scroll down to it)

My personal opinion, not worth much perhaps, is that you will find different practice when fitting driver tires to steam locomotives. In addition to the point Kelly raised, you will NOT want to go through the complicated process of quartering every time you shrink on a set of tires (which will have to be replaced more frequently due to the wear patterns resulting from high-power DA engine operation). As a result you'll want to apply the tires from the outside (and I do not recall having seen any picture of North American practice that did not do so, although I have seen references to the use of Gibson rings on Australian locomotives).

Having a locating 'lip' or shoulder on the outside of the wheel might stop some of the tendency for the tire to 'migrate' outward if it slips or cracks, and get into the rodwork. However, I suspect that if the tire cracks completely across, as I'd expect would happen in a case of breakage that relieves the 'interference fit', it's possible that centrifugal force would open up the gap enough to allow the tire to deflect over the shoulder, at least enough to jam things up.

I have always been concerned that the SP-type welded security clips weaken the rim or the tire in unpredictable ways. If I recall correctly there were actually directives that prohibited welding on driver tires (although this might be the old style of 'autogenous welding' with no shielding gas that make me wince a bit when I read about them). I tried to find clear pictures of the SP clip installation procedure but wasn't successful -- someone from CSRM probably has data.

It is also true that the recess for the Gibson ring is a nifty source of potential stress raisers, particularly after the wheel with ring installed has run in the rain and dirt for a while, but the added metal in the flange and fillet may make this less of a disadvantage.