Traction Wheels

Model Railroader General Discussion (Model Railroader)
1

I study past postings but didn’t directly see a basic primer on traction wheels for steam loco.

I have small layout that required a steep grade (3-4%) - mining prototype. My 2-8-0 Consolidation can only pull about 6-7 ore cars up the grade. What specifically are traction wheels - a set of drivers simply fitted with something like a rubber o-ring? Can traction wheels be installed on any loco after purchase or only by mfg.? If after purchase - source?

Do I simply need to purchase a bigger engine #-10-#? Would it make much of a difference?

I thought about putting very narrow strips of a rubberized coating at regular intervals across the rails (like the rubberized paint you can use to re-coat dishwasher racks). Not too much as to disrupt power pick-up - but just enough to allow for better traction. Anyone experimented with this idea?

Thanks!

2

Oh - additional question. I can always bring into a service an additional engine to help the train up the grade - but would have to push from behind - would a pusher engine cause derailments? I am running dc - so not sure how I could control the engines seperately as to not have the pusher exert too much force to cause de-railments.

3

Yes, traction tires are specially-made wheels with rubber inserts in them. They aren’t simply regular wheels with rings added, though. You would need to get a set of traction tires / wheels specifically made for your model. I don’t know if anyone makes after-market traction tires, but you could look.

I’ve got 2 engines with traction tires. I’ve got a diesel switcher, which is very light because they took all the weights out to install the sound, and an 0-6-0 switcher. The diesel came with the tires on, and the 0-6-0 came with them in the box, and I’ve never installed them. Of course, I have a pretty flat layout and I only run short trains.

If possible, try adding weight to your engine. That is usually the first step to improving pulling capability.

“Helper engine” operations are interesting, but with DC I think they would be pretty difficult to control.

4

THanks for the insight.

I see Walthers offers traction tires for steam (small, medium, large - would help if they gave diameter dimensions!) that appear to be after purchase add-ons. I will look to see if my LHS has in stock.

5

I would think the load you describe (6 cars ish) is quite prototypical for such a grade and that type of engine. May I ask why you wish to run trains that are longer, and how much longer are we talking about?

As for pushing, if they are the short and light ore cars, you can count on derailments. Two things to counter that…somewhat…are to weight the cars heavily (now you will have to push them [sigh]), and to mount the couplers on the frames. I have the MDC (I think) little red guys with the horn-hook couplers mounted on the snap-fit trucks, and they are next to useless when towing them with more than four in a consist. Pushing them is good for the giggles.

6

Excellent point - I guess just because I bought a 12 pack doesn’t mean I should be able to pull them all! The cars do have body mounted couplers.

7

[:)]

If the faster locomotive is bogging down on the upgrade, then the slower speed of the train should compensate for differences in locomotive speed. So the slower motor that would be dragging down the train on the level will become effective on the upgrade. If the opposite were true, then then the train would not need the helper, right?

Model couplers have relatively more sideways movement than prototypes (to accommodate our sharper curves). This often causes problems with pushing because the couplers flop to the side and cause derailments and uncouplings. It may therefore be necessary to put the helper on the head end.

[:)] [:)]

8

Unless a model is made with traction tires on it, you can’t add them without changing the wheels because the wheels have to be grooved for the tire to fit into. Trying to add a traction tire to a wheel that isn’t grooved will cause the engine to lose electrical contact with the track and can cause them to lean to one side.

Here in the dry Arizona climate we don’t like traction tires because they dry out and come off after only a year or two. I have passed up on purchasing several different models because they have traction tires. I currently have 3 or 4 Rivarossi Big Boy and Cab Forward steam engines that I don’t run because the traction tires have dry rotted and came off, and all the side rods have to be removed the put a tire on them.

Double-headed engines would be your best and most prototypical solution, other than running only short trains uphill. Both engines on the front end instead of one trying to push would be best.

9

You can do almost anything if you have the skills, patients, tools and money. But in the long run , you’ll be better off buying a loco that pulls better or already has traction tires installed.

Your talking about taking the drivers off the loco and machining grooves in the wheels to accept an O ring of the proper size. Something an average modeler probably would not want to tackle.

10

Probably more than the REAL 2-8-0 could.

'Traction tires are a cheap way to get ‘pulling’ power. They reduce electrical pickup, break, absorb oil, and require a groove cut into the wheel for accomodation.

A better way is to make heavier and use a bigger motor. REAL RR’s added driving wheels - (2) 2-8-0’s / 2-10-2.

Or the combination.

… and lose the electrical power. Sorry.

If you double-head: matching identical engines works best.

11

We have a 5% grade on the layout here, and it causes problems with how many cars smaller steam engines can pull upgrade, just like it did on the prototype (Silverton RR).

We’re lucky to get one boxcar and one combo car up the hill with an MDC 2-8-0, just like the real locomotives pulling real cars were. A Spectrum 4-6-0 can pull two 34’ boxcars, or two 34’ flatcars and a shorty bobber caboose upgrade, and a Spectrum Shay can pull two tankers, a gondola, a rail and tie car, a derrick car, and a work caboose up without too much wheelspin. A Spectrum 2-8-0 can haul 4 34’ boxcars, but add a caboose and you’re gambling.

Sometimes it’s a fight. Sometimes we have to back up and try again to make it up grade, sometimes we have to wait for a helper engine, and sometimes we just dedicate a double header to pull the grade, again, all just like the real railroads did. I enjoy winning a long struggle to make it upgrade, whether it’s driving a model train, or my jeep on the 4x4 roads that most of these old grades have become today. Hillclimbs are fun. More fun if you beat the hill.

All that said…friction is a function of downforce per unit area, times total area, times the coefficient of friction. In plain english, increasing friction means increasing the number of pounds per square inch, increasing the number of square inches of contact at that pressure level, or increasing the coefficient of friction, (using a “stickier” surface).

Just about anything you might use to increase the friction coefficient is liable to decrease electrical contact. Sand on the rails ain’t gonna work, here.

Filing the drivers flat, leaving the flanges alone, might increase the area of contact, but the downforce per unit area will decrease proportionally, you are just spreading out the weight of the loco, and not changing the overall equation.

You can lighten the load, fewer cars, lighter weight cars, but then you run into derailing pro

12

cacole, try getting some Stewart traction tires. They don’t dry out like the old Riv tires. Probably a different synthetic compound. Fit them to the wheels with an emery board after installation and they do pretty good. I have one that’s about 15 years old.

13

Gentlemen (maybe a lady here - not sure)

Thanks for all the expert advise. I think I will add a helper to the head of the train - will create more interesting operation as well. Just need to figure out an appropriate place to add a spur to park the helper while not called into service.

Being new to the hobby (after a 30 year hiatus) - I guess my expectations as the to the pulling capacity of a 2-8-0 were not realistic.

Thanks again!

14

As long as your rolling stock is reasonably well-weighted (NMRA recommendations-or-so) and has body-mounted couplers, there should be no reason why you can’t use a rear-end pusher loco on your trains. It helps if the locos run at a similar speed, and most reasonable quality locos should do so, if they’re the same type and from the same manufacturer. I operate with DC also, and due to fairly stiff grades and plentiful curveature, regularly run double-headed steam (or diesel or a combination of both). I also don’t hesitate to add a pusher to the rear when required. If your locos will run reasonably well together, then they should also run reasonably well front-and-rear on a train. It’s equally important that both locos start moving at the same time, by the way. I’ve also had good success running a fairly long train with the locos spaced out throughout the length of the train, although this was done just as a test and is not my usual practice. The train was 65 cars (mixed manufacturers, most with plastic wheels) with 4 Athearn Mikados (modified), on a 2.8%(roughly) grade laid out on multiple curves. The entire train was on the grade, and because the line was a dead-end (second level of the layout yet to be built), I also had to back the train back down the hill. The real test of a rear pusher is if your layout has places where part of the train will be moving uphill, while another part is moving downhill, as slack action can play havoc with a train, as it can on the prototype.

If possible, try adding weight to your locos, and, as mentioned, try to keep it balanced, especially with steam locos.

Wayne

15

Virginian,

Thanks for the suggestion. I have the Stewart tractiion tires, which is the only brand of replacements available that I have ever seen. They, unfortunately, seem to dry rot or stretch and slip off just as bad as the originals.

Our problem out here is the dryness combined with the summertime heat because the clubhouse has no air conditioning or central heating. We use evaporative coolers in the summertime and a propane heater in the wintertime, but they run only when someone is at the clubhouse.

16

But be careful here. Adding weight without increasing motor size could lead to overheating, probably not a big problem if the duration of your climb is not too long.

Jim

17

Unless your loco is equipped with a very poor quality motor, you’re not likely to overheat it enough to cause any damage. Most good quality locomotives, at least in HO scale, are over-powered and under weighted. When I was testing the Athearn Mikado to determine how much weight could be safely added, I fashioned a “saddle” of sheet lead to drape over the boiler, then applied power while I held the tender with one hand. Since the loco could not move forward, the drivers easily slipped, indicating that it had sufficient power to run at that weight. The lead saddle weighed 22 ounces, far more than I was able to cram into the modified loco.

Wayne

18

I once had an engine that was missisg it’s traction tires, so I filled in the groove with silicone bathtub sealant. I don’t remember that ever coming off.