Is there any simple way to "make" a traction tire? I was wondering for
instance if one could carefully paint a thin layer of that rubber paint
stuff that is used on tool handles onto the wheel of a locomotive? Yes, I
know it sounds crazy, but I can't beileve that the only way to increase
pulling power is to continually cram microscopic amounts of lead into a
boiler shell that is getting harder & harder to remove.
Thoughts?
dlm
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
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
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,
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
been
that
in
purpose
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. :^)
can
bearings)
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.
HO.
and
tension
lot of
have
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.
trains.
wagons.
bankers. :^)
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.
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:
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:
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
http://www.geocities.com/budb3 /
PROTOTYPE TECHNICAL INFO FOR MODELRAILROADERS
http://www.freeyellow.com/members4/budb /
Moderator of:
MR TECHNICAL HELP GROUP
http://groups.yahoo.com/group/mrtechhelp
COUPLER HELP GROUP
http://groups.yahoo.com/group/mrcouplers
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
Western Pacific Model Railways
http://www.wave.co.nz/~lakewood/MyWP.htm
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
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:
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