Traction tires

Traction tires are the fastest way to burn out a motor. You want to add weight until the motor is drawing it's full RATED current and the wheels are still slipping. If the wheels can't slip at maximum current, the motor WILL burn out.

Don

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Yes, it's been done, and I don't recommend it. It will come off onto the rails (eventually). If it slips, add more locomotives (just like the real railroads do).

-John

Just limit the weight so that the mechanisim will slip at maximum current - problem solved.

What started this is that I got one of the Spectrum 2-6-6-2's and have been rather disappointed in its performance. I have 2% grades with shallow curves and the best it does is about 10-12 Athearn hoppers on those grades... not what I'd call stellar performance. I know that an engine that size isn't supposed to rip up the rails, but I'd think that numbers more in the 20-25 range would be more appropriate.

A friend who is "in the business" suggested that this has been a problem with engines that come from China recently. They make very good models (well proportioned), but really don't understand the concept or the purpose for which they are intended. So yo end up with great looking models that can't pull worth a dang. The Athearn 2-8-2 comes to mind as well in this regard. So, I'm looking for a rather simple way to increase performance.

dlm

While many things can be done to improve loco pulling power (more weight, better rail contact, different wheel or rail metals, traction tires, magnetism, etc.), usually it's not nearly as big an issue as train 'drag'.

A model loco, assuming all it's wheels are powered and it's reasonably weighted, will 'pull' about 80% as well (in scale) as the prototype. The difference is due largely to the wheel and rail metals being different than those of the prototype. Brass and nickle silver are 'slipprier' than steel. The usual lack of (effective) springing or working equalization on the model also degrades pulling power.

The BIG problem, however, is that our CARS don't roll nearly as well as prototype cars. The BEST of them may come close, bit most cars are miserable in this regard. This is especially true of older items. Usually, for a given amount of effort, you can incrase pulling power a LOT more by improving your car fleet's rolling charicteristics than by trying to improve loco tractive effort.

Invest in better trucks and wheelsets, and clean the ones you intend to keep. Dirt on the wheel tires, and 'fur' (dust, cat hair, etc.) wrapped around axles GREATLY reduce free rolling properties.

Dan Mitchell ==========

Pacific95 wrote:

Adding something for traction to the tires of the driving wheels won't last very long at all as the diameter between the two sides will be different, causing a very rapid wear of the tires. In addition, you need to get all of the tires to the same diameter or the same thing will happen. That's the first problem. Second problem is that when adding traction tires, you quickly overcome the ability of the motor to keep turning the wheels when slipping. This means burned out motors in short order. If you want more traction, increase the weight of the loco by any means possible. Forming pieces of lead to fit around the drivetrain and in places like the cylinders and so forth can do a nice job of increasing the capabilities of the loco to pull a decent sized train. I'll note that that loco should indeed be able to pull 25+ cars up a 2% grade.

-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works every time it is tried!

Hi Bob,

Jim Kle>Adding something for traction to the tires of the driving wheels won't last

Hi:

As stated in replies, there are many factors effecting tractive effort of locomotives including weight on drivers, coefficient of friction between tires and rails, grades, car rolling quality and weight plus flange friction. All of these influence the results. Achieving optimum operation is an art.

For in depth discussions on measuring and calculating most of these and deriving solutions, see first site below.

Hope this helps.

Thank you,

Budb

Author of:

MODELRAILROAD TECHNICAL INFORMATION

PROTOTYPE TECHNICAL INFO FOR MODELRAILROADERS

Moderator of:

MR TECHNICAL HELP GROUP

COUPLER HELP GROUP

I just bought a Rivarossi Berkshire new 5400 series with the improved motor and drive. But it still uses 2 traction tires and the fellas at trainland told me they are there because it's a light engine. It weighs one pound and there's plenty of room under the boiler to add weight, so I'm thinking about removing the tires permanently. The drivers do not have grooves on this model.

Can anyone tell me how to lift out the drivers to remove the tires or should I just snip them off? I'm also trying to eliminate the sway and a poster recommended shimming the axles--is there a website with instructions for disassembling Rivarossi drivers or is it self-apparent?

Also has anyone added weight to a Rivarossi and found this to reduce sway? (BTW temporarily removing the tires did not eliminate the sway--it looks like a sloppy siderod issue.

Thank you all for your time, Robby

First check if your carriages are free rolling, my definition is if they can roll down a 2% grade their OK. Next check the weight of your cars. If they are to the NMRA standard, each car is at least one ounce to heavy for HO. Then check your locomotive, remove any springs that hold down leading and trailing trucks. After doing all this, if your model still cannot haul a prototypical load you can add some weight. If it still cannot achieve a prototypical load your curves are to sharp. See my web page for further details. Avoid traction tyres, they decrease electrical pick up, and introduce poor tracking to the model.

Just an aside here, probably of no interest to anyone but Terry and me:

Is your definition for rolling vehicles or starting vehicles? (stiction being almost as great as rolling resistance on pin-point bearings)

I diagree with you here - IMHO the trucks should have the minimum spring tension that allows them to track and hold the rails correctly. That requires a lot of care and trial and error to set up but I think it is worth the effort to have trucks properly leading locomotives into curves.

My layout, like those of many modellers will not hold prototype length trains. I work on the principle that each model wagon represents 4 prototype wagons. This brings forward the moment when trains need double heading and bankers. :^)

My curves are too sharp! 8^{

Regards, Greg.P.

Something's peculiar here.

The drivers MUST all be the same diameter to work even moderately well. If there are traction tires on a wheel that wheel must be either grooved to the thickness of the tire (the usual situation), or the whole wheel must be made undersized (relative to the other drivers) to account for the thickness of the tire. Either way, you can't just remove the tire and expect things to work properly. You'd need to install a metal supplementary tire of the same thickness as the traction tire.

If the drivers ARE all the same diameter, and NOT grooved, than it can't work well with the tires ON anyway. Remove them, and add as much weight as you can, without overloading the motor.

Any way you look at it, traction tires are a BAD idea. They are, at best, a quick, cheap, fix for errors in design. If everything else is gotten 'right' you don't need them. They are rarely even close to round, and cause wobbling and tracking problems. They collect and distribute dirt. Most don't last long. They either break, or stretch. If they stretch, they come loose and slip on the wheel, may become snagged in siderods or gearing, and aggravate the earlier mentioned out-of-round and tracking problems. And, on an older model , you may not be able to find a replacement.

Dan Mitchell ==========

robby wrote:

Your suggested free rolling on 2% grade standard is a great place to start. Achieving that for most of one's rolling stock would be a HUGE improvement over what most of the hobbyists are actually trying to run. LOTS of our club member's cars won't roll down a 4% grade! And these guys often gripe because their locos don't have good pulling power. Some of these types are resistant to attempts to educate them on improving their rolling stock, but they are good at complaining. They might as well be dragging wooden blocks down the tracks!

While the suggested 2% figure is a decent target, you can do better, but it's more work. I *TRY* for the same performance, self starting, on a 1% grade. I have lots of cars that meet this standard, but not all. And they don't always, or even usually, STAY that way without occasional maintenance. The common 'dirt tread' that builds up on wheel is more than sufficient to end 1% grade rolling. Grit, fur, lint, hair, etc., in the journals assures poor performance. You need to inspect, test, clean, and repair your rolling stock periodically if you hope to maintain even the 2% standard, let alone 1%. It's a never ending battle.

Usually, the 1% standard can be achieved without the use of lubricants. Lubricant's CAN sometimes improve rolling ... for a time. They also collect dirt and soon loose whatever improvement they initially offered. Then they have to be cleaned, and re-lubed. Additional maintenance to be avoided whenever possible. I do have a few assorted all metal trucks that just won't roll well without lube. These are odd-balls that resist attempts to put better wheelsets into them, and have certain properties (odd sideframes, etc.) that make their continued operation desirable. These 'problem children' are just more work than the other cars.

The ball bearing HO wheelsets from Intermountain are REALLY nice in SOME problem sideframes, especially brass 6 or 8 wheel trucks on passenger cars and heavy flat cars. These trucks have notoriously POOR rolling characteristics. Unfortunately, the IM BB wheelsets are moderately expensive, but that's not much if an issue if they turn an expensive brass passenger car into a good performer. They easily meet the 2% test, but usually NOT the 1% test. They do NOT roll as well was a GOOD needle point bearing. That's NOT surprising ... prototype roller bearing trucks don't roll as freely as well maintained old friction bearing trucks either (but that's a whole other story we've discussed here before)! HOWEVER, the IM ball bearing wheelsets do work well in applications where fitting GOOD needle point bearings may be difficult at best. They also carry high weight loads, and still roll well (a problem with the delicate needle-point bearings).

I also have reservations about using the ball bearing wheelsets on electrically active tenders, due to electrical contact issues. The current flowing through the tiny balls will likely cause erosion and pitting that will destroy the trucks. Even large bearings have this problem. It MAY work, for a time, but some experimentation is needed. Strategically placed contact wipers could bypass the current around the bearings, but cause more drag which is exactly what you are trying to get rid of.

I DO use sliding contact wipers on some equipment, it greatly improves electrical contact, but it DOES cause drag. That just makes getting all the OTHER sources of drag to a minimum even MORE desirable.

Dan Mitchell ==========

Terry Flynn wrote:

Hi Dan

Problem with painting a rubber tire on a wheel is that you will increase the rolling diameter of that wheel. Thus for each rotation of the wheel it will travel a tad bit further along the track. This will be a problem if the wheel is tied to other wheels via side rods or internal gears. I had this very problem with a German diesel which had the wrong thickness (to thick )rubber tires on the wheels one 1 axle in a 4 axle driven loco. The rubber tired wheels were trying to travel futher for each rotation than the rest of the metal wheels and this caused a surging as the loco moved. Also take note that for every rubber tire you have you have less wheels collecting current from the rails.

Bare in mind the Euro manufactures make extensive use of rubber tires and with great success but they are fitted into a groove in the wheel tread so the tires don't roll off. This groove's depth must be exactly the same as thickness of the tire in use so as to maintain the correct rolling diameter of the wheel. I still have a few of my Euro locos (I have gone US now). One is a Roco BR194 that has a hughly powerfull motor and 17:1 gearing. Of the 6 driven axles 2 axles have wheels with traction tires and this loco can at 2 volts drag backwards 3 Proto 2000 GP9's.

Nigel

Hi Bob,

I finally got tired of trying to give my optical code away and I went back into the train business. For every post on sci.optics, there are

20 on the model train news groups. Guess I got tangled up with a bunch of optics geeks a bit too long. :-). Counting rivets is much more fun.

Do you still have the On3 Kemtron Shay or do you know where I can find a boxed, un-messed with copy in unbuilt condition? If so, how much ?

I'll be selling lots of detail photos of D&RGW circa 1979-1981 era photos and On3 D&RGW built models via the Original Whistle Stop in Pasadena, CA. with thumbnails on my web site as well as custom built ship models.

I still write optics code but just for the day job.

Sincerely,

Jim Klein

The definition is for starting resistance. Static friction is greater than dynamic friction, and experimentally it is easy to test compared to dynamic friction. Have a 2% (1 in 50) grade. Place the wagon on it. If it rolls down the grade it passes. The vast majority of HO models pass if they have pin point axles and bearings.

For small scales the trucks have no function other than looks. Flange wear is not a problem with HO locomotives. . The minimum spring tension ( we should be saying compression) is zero, thus no need for the spring. There are 2 general reasons why your trucks will derail, one is incompatible wheel track standards, the other is lack of clearance between the locomotive body and the truck. Things such as outside cylinders and coupler boxes are common culprits. Excess sideplay and poor location of the pivot point on pony trucks can also be a problem on rough and sharp curves, springs might help, but it is better to correct the cause of the problem. I have been running steam locomotives for over 20 years without leading and trailing truck springs. There have been plenty of RTR models without springs on trucks. All the model locomotives on my web page have no springing on the leading or trailing trucks.

It depends on how you interpret your layout grades. On the prototype engineers often refer to compensated grades. What this means is they quote a steeper grade for a curved section of the railway than the actual grade. So on a model railway a 1 in 50 grade on a 760mm curve is roughly equivalent to a 1 in 30 compensated grade. Now the models are probably hauling close to protypical loads for 1 in 30 grades compensated.

Or your grades are steeper then the prototype you are modelling, which is the other common problem.

Greg, try this experiment, remove the leading and trailing trucks from one of your locomotives which you know the maximum train load, and test its new maximum train load. It should be able to haul a few more carriages easily, and should stay on the track. Friends often would tell me how model steam locomotives can't pull prototypical length trains. It was often true for models out of the box. Removing springs usually is all that is needed. A little extra weight to balance the model sometimes is necessary. I added mass to some of my earlier large steam engines. My 4-8-2 has a mass of about

420g. On my layout with a 1 in 45 grade on the straight for a length of about 30 bogie wagons, minimum curves of 910mm radius with 1 in 80 grades, it can haul 40 bogie wagons, total train mass is about 4kg. That's about double the train length of my prototype. It's also much better than what is predicted on my web page for a model of this weight. This is because the rolling resistance of the train is less than my worse case values used and the chart also assumes worse case low driving wheel friction. . A combination of factors including train rolling resistance makes the big difference, a large number of carriages were fairly new when I did this test last week. The amount of oil on the rails is also another variable, and finally none of my steep grades are long enough.

One thing I forgot to mention which is a factor in poor steam locomotive tractive performance is to test the tender for free rolling qualities.

I don't build locos that way - a 4-4-0 with the bogie guiding the loco looks much better in operation than an (4)-4-0. I'm not concerned about flange wear but a bogie guiding the loco avoids the driving wheels picking points and frogs.

A truck or bogie is a very lightweight item of rolling stock and a great wad of lead can spoil it's looks.

When does large tolerance end and incompatibility start. My wheel/track standards would be unacceptable scaled up on the prototype but they certainly pass the "compatibility" standard.

My cure for "the problem" is to ensure that there are no clashes of mechanical parts and to ensure that bogies and trucks guide the loco.

Sure, I started that way too, but we seem to have diverged on different routes to solve the same problems.

True, but I'm modelling a specific section of line where there were 1:45 gradients and sweeping curves - I don't have the space to lay realistic scale curves nor to have the length for full length trains.

My gradeints are actually gentler than the prototype by a fraction.

Been there, done that. I'm modelling a line where a small loco policy changed to a large loco policy over a short number of years. The only "problem" locos I have are tender drive models and underweight Rivarossi Pacific and 2-8-2.

"Dan Merkel"wrote

Chief, Push it with your Akane 2-6-6-2. Cordially yours, Gerard.