steel tires

This forum is dedicated to the Live Steam Hobbyist Community.

Moderators: cbrew, Harold_V

Marty_Knox
Posts: 1724
Joined: Thu Jan 09, 2003 6:50 pm
Location: Michigan, USA

Re: steel tires

Post by Marty_Knox »

Locomotive tires were available in 7 grades. 3 non-heat treated, and 4 heat-treated to different levels of hardness.
Pontiacguy1
Posts: 1566
Joined: Thu Apr 26, 2012 10:15 am
Location: Tennessee, USA

Re: steel tires

Post by Pontiacguy1 »

You do not have to make a step in your tires... But I would recommend that you do that if you are not going to press your wheels off of the axles. The chance of you getting it to set in the right position without a step in that scenario isn't very good. If you are going to tire up a wheel off of the axle, then you can machine both surfaces straight and then drop the tire around the wheel laying on a flat surface. Then machine them afterwards. Yes, the rule of thumb is a thousandth of an inch of interference per inch of diameter. You can go slightly higher though. For instance, when doing an 8 1/2" diameter wheel, I typically just make it 0.010" interference and leave it at that. If you are going to cheat a little bit on interference, cheat to the high side instead of the low side.

I also use the oven to heat them up. Put that sucker on 500 degrees and leave it for about 45 minutes, depending on the thickness. It will then be hot enough and expanded enough to get on there. If you are smart, you'll go get a cheap cookie sheet to put your tire on while heating in the oven instead of using one of your wife's good ones! If the tire is small enough, dropping it directly on the eye of an old resistance coil type stove (not a flat top) works well too.
User avatar
NP317
Posts: 4557
Joined: Tue Jun 24, 2014 2:57 pm
Location: Northern Oregon, USA

Re: steel tires

Post by NP317 »

Hardened steel locomotive tires are not the goal, as they reduce tractive force of the locomotive from loss of adhesion.

Pennsylvania Railroad did extensive research on steel tires, trying to arrive at the best combination of wear and adhesion.
A long-gone Friend of mine was involved in that research.
He said they even considered "compound steel" tires with "slippery" flanges and "sticky" adhesion surfaces. They never achieved that combination while he was involved.
Who knows what happened since then? A complex subject.
RN
Pontiacguy1
Posts: 1566
Joined: Thu Apr 26, 2012 10:15 am
Location: Tennessee, USA

Re: steel tires

Post by Pontiacguy1 »

I have read somewhere that some locomotive builders also used a 'high adhesion profile' on their driver tires too. Don't remember exactly where, maybe in Europe? Not sure. The profile was such that it made the largest contact area with the rail head to promote better grip.

I believe that the composition and hardness of steel tires are like just about anything else on a steam locomotive: a trade-off. If you make them softer, you get better traction, but they wear quicker. If you harden them up then they wear longer, but are more prone to slipping, chipping, cracks, etc... On our models, I doubt that anyone would really run the steel tires enough to completely wear them out, even un-hardened. If they did, it would likely take a number of years to do.
ccvstmr
Posts: 2230
Joined: Sat Jan 04, 2003 10:37 am
Location: New Lenox, IL

Re: steel tires

Post by ccvstmr »

daves1459 wrote: Thu Sep 12, 2019 1:06 am I took the time to look up locomotive tire strength in my 1925 encyclopedia. In those days they listed tensile strength instead of hardness. For passenger locomotives 105,000 psi was specified, 115,000 psi for freight locos, and 125,000 psi for switchers. (Why a lowly switcher is higher than a passenger loco stumps me.) Anyway, good luck, Dave
If I had to guess, I'd say the switcher tensile strengths were dictated by numerous start/stop cycles, braking and reversing in the course of normal switcher duties. "They" would not have had to generate those kinds of data points without a valid reason. Otherwise, have nothing to substantiate that comment other than gut instinct...and all the possibilities of a definite maybe! :lol: Carl B.
Life is like a sewer...what you get out of it depends on what you put into it!
I don't walk on water...I just learned where some of the stepping stones are!
I love mankind...it's some of the people I can't stand!
rkcarguy
Posts: 1730
Joined: Tue Aug 22, 2017 10:33 am
Location: Wa State

Re: steel tires

Post by rkcarguy »

FYI, I just pressed some wheels onto axles a couple months ago and without shoulders it's almost impossible to get them to run true. So regardless of it being a wheel to axle, or tire/wheel relationship I would highly recommend turning a shoulder and dropping the wheel/tire onto it.
I would not recommend hardened steel for wheels, due to traction issues and brittleness, and it's simply not needed. My S12 for example, is shaping up to be in the 1,000# range but is only 1/250th of it's full sized "brothers" weight at 1/6th scale. That's only 125#'s on each wheel.
User avatar
NP317
Posts: 4557
Joined: Tue Jun 24, 2014 2:57 pm
Location: Northern Oregon, USA

Re: steel tires

Post by NP317 »

The steel I used for the tires pictured above was thick-wall DOM tubing (Drawn Over Mandrel), low carbon steel, sliced into rings.
I machined a shoulder on the cast iron wheels, machined the tires to thickness and ID to match the wheels (minus 0.006" dia.)
with a matching ridge to contact the flange on the wheels, and dropped the heated expanded tires onto them. With gloves and tongs!
All 8 tires set true. Maybe I was lucky.
I then turned the final tread profile on the assembled axle sets.
I'd do it again that way.
RN
User avatar
Harold_V
Posts: 20231
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: steel tires

Post by Harold_V »

NP317 wrote: Thu Sep 12, 2019 9:46 am He said they even considered "compound steel" tires with "slippery" flanges and "sticky" adhesion surfaces. They never achieved that combination while he was involved.
I suspect that with today's technology, they could achieve the goal with induction heating. Given enough power, localized areas can be heated so quickly that adjacent areas are not affected.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
User avatar
Bill Shields
Posts: 10459
Joined: Fri Dec 21, 2007 4:57 am
Location: 39.367, -75.765
Contact:

Re: steel tires

Post by Bill Shields »

i am a subscriber to the 'shoulder' method for tires.

shoulder on the inside of the tire, a matching recess on the center hub that has clearance on the OD and will not bind during assembly.

drop them on hot until the shoulder meets

allow to cool

turn everything true on a fixture or after assembly.

takes a lot of worry out of the process.
Too many things going on to bother listing them.
daves1459
Posts: 279
Joined: Mon Jun 07, 2010 7:58 pm
Location: Plainfield, Illinois

Re: steel tires

Post by daves1459 »

Unless there's something I don't know, that isn't true. Mild steel is not heat-treatable by conventional means, as the carbon content is too low to achieve the desired hardness. One does have the option of pack hardening, or having carbon infused by a carbon rich heat treat furnace atmosphere, but it most likely would be simpler to use 1045 steel instead.

Hello Harold,

After rereading my submission I can see how it would cause some confusion. I can see my use of the words "heat treat" and " hardening" would lead the reader to think the tires I am referring to are actually hard. In reality they are not at all what would be considered hard. After the heat treat process the are more "toughened" than hard. The Rockwell "C" 20 - 25 hardness is just above the lowest limit of the "C" scale. "20" being the lowest usually printed and just slightly harder than as the raw bar stock is received. The "C" 20 - 25 range increases the tires strength to reduce the tendency to crack and peen under repeated hammering going down a steel rail. More important for a model is the slight increase in hardness also makes the tire easier to machine by improving chip formation and surface finish, and it can still be machined with high speed steel cutting tools.

The heat treatment I referred to quite common and I've had it done a couple of times. Attached for your review are a couple of charts taken from the American Society for Metals' book "Heat Treaters Guide, Standard Practices and Procedures for Steel". Fig. 2 shows the relationship between carbon content and maximum hardness. In the SAE system of steel designation the last two digits are the % carbon content. So a SAE 1020 steel has .20% carbon. I superimposed a red line representing 1018 and 1020 steel. As can be seen the highest potential hardness for .20% carbon in commercial practice is around "C" 45. I think this curve is rather optimistic for SAE 10xx series steels and more applicable to 41xx, 51xx, and 61xx series steels that alloyed to enhance hardenability.

The curve "1018: Hardness Versus Tempering Temperature" is specific to 1018 steel with no case hardening. I've superimposed the "C" 20 to 25 harness range. Notice the degrees F tempering range is well above the 400 F or 500 F used for shrinking the tire onto the wheel.

Like most of the responders to this thread I don't think heat treatment is necessary for the model. I did it for my 999 project because the tire was rather thin and almost 12" in diameter over the flange. I wanted the metal stable and as easily machined as practical.

Dave
Attachments
scan0002.pdf
(302.55 KiB) Downloaded 143 times
scan0003.pdf
(318.37 KiB) Downloaded 131 times
User avatar
Dick_Morris
Posts: 2841
Joined: Sat Jan 04, 2003 2:09 pm
Location: Anchorage, AK

Re: steel tires

Post by Dick_Morris »

As a comparison to a prototype, 57" driver tire for a WWII USATC S-160 Consolidation. .065 interference on a 51" center.
Attachments
952-S-54560 Wheels - Tire Section.jpg
Post Reply