The cars in the set would be either the Rio Grande yellow passenger cars or a similar steam era freight car set.

2-8-8-4

Clarification:  My comments are generally pertaining to the model world.

I also think adding even one rubber tired driver or the bullfrog snot probably has a much greater impact than removing a lead or trailing truck spring from those engines that have them.

As for me--I despise the rubber tires and am glad Bachmann left them off the 2-6-0--and I'd never expect a 2-6-0 to pull a long train (unless it was one of the larger 2-6-0's that ran on the SP in flat portions of California where they were known as "valley malleys" and actually did pull 50 car trains.)

Why am I so against rubber tires?  It has come to light that some of the companies who apply them put them on a non-geared driver, which over time results in excessive wear of the valve gear (holes wear egg-shaped).  Also, if the main rod is one solid piece crossing multiple axles, that by  itself can lead to excessive wear over time.  The "better" model steam engines (at least in the larger sized steamers) have multiple piece main rods just like the prototype.  If the steamer is going to have rubber tires, the multiple section main rods are a good idea for durability due to the forces on the pins during starts and stops--which are exacerbated by the rubber tired axle(s).

Apparently Athearn learned from the problems experienced on a number of Genesis Series steam engines (as reported by at least one reviewer online), and did the SP MT-4 4-8-2 with 3-piece main rods, similar to the prototype.

John

Quote from: jward on May 02, 2012, 11:49:17 AM
sorry, 2-8-8-4 but it's true, increasing downward pressure on unpowered axles decreases tractive effort, lessening that pressure increases tractive effort.

My argument is that the decrease in tractive effort due to having a sprung lead/trailing truck, in the model railroad operating conditions and environment that I usually have (ie not running 2-6-0's and short trains but running big engines that are already properly weighted with long heavy trains) is negligible for practical real-world purposes.

Also, it is worth noting that the real railroads were far more interested in weight on drivers than weight on lead/trailing trucks (as long as the axle loadings were beneath the maximum).  The real railroads realized that weight on lead and trailing trucks had only minimal effect on tractive effort.

We wouldn't even be having this discussion, or rather it would not have taken this turn, if it weren't for the fact that some folks desire their model locomotives to outperform the pulling capacity of real locomotives! Again, my personal preference is for operational reliability and good tracking over maximum (model) pulling capacity, but not everyone will have the same approach as me, and that's ok.  It's your railroad--if you don't want the springs, then remove them--it won't bother me one bit at all.

There is a reason that railroads obsessively avoided 4% grades (excepting Saluda).  Even today, there is a sustained 2% to 3% grade in PA over Keating Summit that requires one 3000 horsepower six-axle diesel for every 8 loaded hopper cars (according to a dvd)--and most steam engines did not produce anywhere near 3000 horsepower.  As a design engineer, I'd never think of designing a prototype alignment that steep, because it borders on economic lunacy.  That's also why the PRR built Horseshoe Curve--to avoid what would have been a 3% grade.

2-8-8-4

Lewis K. English, Sr. of Bowser Manufacturing, who passed away a couple months ago at I believe age 93, is a member of the Model Railroading Hall of Fame.  He was inducted in 2003.

Here's a link I found to some of the members:

http://www.hmahobby.org/railroad-hall-fame.html

Many of the folks mentioned above are indeed members.

Rogertra--

Thanks for your comments.

Although one layout I built had the complex turnouts to save space in a yard ladder (based on either a John Allen or Armstrong's "spaghetti bowl" type track plan), my current layout went minimalist for the reasons cited above.  Instead I'm trying to emphasize the scenery and put trains in a rural America context...it's a work in progress.

I love all the complicated turnouts--I really do--but they can become a maintenance headache.

My current layout runs around the outside of my basement to save floor space for other things (kids to play, etc.) and has only a total of 5 turnouts with a loop at each end of the layout.  We just like to turn trains on and let them roll at my house...it's not for everyone.

For me the turnouts are the biggest headache--any dirt and I may have a brief power drop--enough to stop a train once in awhile, so I religiously apply the Atlas Conductalube to the rails to keep them clean (any excess evaporates).

2-8-8-4

Quote from: rogertra on May 01, 2012, 12:25:05 PM
By removing the springs over the trucks, and letting the trucks just go along for the ride, we are, in effect, converting all our locos to "switchers" and putting all the available weight, properly distributed, on the drivers.

I can agree with the above statement.

As an aside, coming over here from the Atlas HO forum, this is as contentious of a thread as you'll hopefully ever see me post.  Hopefully, it's more constructive than contentious, but others will have an opinion on that.

First of all, it seems Roger is or has been dealing with a lot of lighter weight--perhaps sometimes even underweight--steam locomotives.  If the engines are basically underweight, then I will concede the lead/trailing trucks could possibly be an issue.

The other observation I'll make is if your motive power is a 2-6-0 that can pull say 7 cars, and you add 3 more cars pulling capacity--that is actually quite a big improvement.

Also, I do not believe in operating my engines at their maximum limit of adhession--the point of impending wheel slip--so my ratings are always conservative in favor of long term locomotive durability.  I learned many years ago when playing with my own and my friends' brass steamers, on an attic layout with 2.5 to 3% grades and 48" radius curves that it was a bad idea to operate engines in a wheel slip or near wheel slip condition.

My perspective on pulling power of models is also a bit different:  When I can take an early 1980's Key Imports/Samhongsa-built steam engine like the Rio Grande L-105 4-6-6-4, take it out of the box, put it on the track, and pull more than 50 cars (including a dozen or so heavy brass freight cars) up the 3% grades at a walk, without any slip whatsoever, the need to gain a couple more cars of pulling capacity is...questionable at best...so it's just not something I'm looking to do.

Finally, where my comments about heavy long trains and tracking of big heavy motive power over turnouts should begin to make sense is that if one is going to seriously switch or even back a long train of up to 50 cars, or even a shorter cut, into and out of yards over complicated switch configurations such as the three way or double slip turnouts--the forces on the motive power are magnified and any out of weight balance issue will come to light very quickly in the form of derailments of lead and trailing trucks.  That is where having the factory installed truck springs on those big steamers is a good idea.  When one or one's friends are playing with expensive rolling stock...well we wanted to eliminate any chance of derailments possible.  So that is why although some would happily delete those lead/trailing truck springs, myself and the local "lodge" members would not.

Best Regards--

2-8-8-4

I'm a licensed civil engineer, so I do know a little bit about traction--and about model railroad trackwork and tracking of engines, since I've been in this hobby for 38 years (since I was 5).

Perhaps you are only running short trains with small motive power.

My experience includes large, heavy trains with large motive power on club sized private layouts and everything else in between.

In your original post you claimed the upward force of springs is enough to reduce model engine traction--and to that I must call "baloney" in most cases.

Do you actually have one of these Alco 2-6-0's?

Are you aware the spring is at the point where the screw attaches the lead truck--such that it is just enough to provide a minimal amount of downforce on the lead truck?  There is virtually no weight transfer at all to the lead truck--the loco weight is on the drivers--the truck would be entirely free-wheeling if not for the very modest force provided by the spring.  The weight of the engine is also significantly more than the force the spring could possibly provide--therefore any "upforce" of the spring is zero for all practical purposes.  Also, the third driver is placed far enough away by itself to more than counter any moment provided by the mild lead truck spring.

Also--locomotive traction is most influenced by weight on drivers--you will never convince me that a heavy brass or zamac articulated can have enough spring force from lead and trailing trucks to cause the "uplift" you are talking about--and I know from personal operating experience the springs are necessary.

Your argument does not wash.

To increase pulling capacity it would be far more useful to add weight to the (light) boiler than to remove the small spring which barely exerts any force.

Respectfully submitted--


2-8-8-4

Quote from: rogertra on April 10, 2012, 07:05:51 PM

There is a simple fact of physics that people keep forgetting and I keep repeating.

For every action there is an equal and opposite reaction.

Therefore, simple physics states that for 'X' amount of force pressing down on the spring(s) over the trucks, both leading and trailing, then that same 'X' amount of force is also trying to lift the locomotive.

Result?  Loss of traction.

Solution?  Remove all springs bearing down on locomotive trucks and you will notice an improvement in your locomotives' pulling abilities.  The weight of the truck alone is usually more than adequate on well laid track and the springs are not required, ever.  If however, you do find that the truck(s) have a tendency to derail, then add a little weight to the top of the trucks to keep them running smoothly.  Do not reinstall the springs.

I must respectfully disagree.

The springs on leading and trailing trucks of model steam locomotives are often necessary when passing through certain complicated HO trackwork--in particular the Peco three-way turnouts, single- and double-slip switches, and also some of the #6 and #8 turnouts of other manufacturers including but not limited to Shinohara and Kato.  This is true even when the locomotives, leading and trailing trucks are constructed of brass and are heavy--the springs help to keep the trucks from "picking" turnouts and derailing (especially during backup maneuvers).

When I purchased the zamac boilered (and heavy) Oriental Limited Powerhouse Series 2-8-8-2's during the late 1980's, I found it necessary to add springs to those trucks that didn't have them for backup maneuvers to be successful without derailing.

Also, there are some locomotives that have limited clearance to "add weight to the top of the truck" because those trucks still have to pivot and clear other adjacent details.

The one Bachmann ALCO 2-6-0 on my layout so far pulls an adequate number of cars for me (about 7 on my layout).  I very much prefer the fact that there are no traction tires to fail or cause operational/wear problems (over time) with the valve gear.  Also, the wimpy lead truck spring on this engine is not strong enough to provide any meaningful, traction robbing "lift".  It is just fine for tracking through my turnouts.

Respectfully submitted--

2-8-8-4

Les--

I'm an HO guy, and my stuff all gets run.  If it doesn't run well, and I'm not able to fix it fairly easily, it is gone for whatever I'm able to get out of it that I can then put into something that will run well.  However, it still has to look pretty good too...

I've been very pleasantly surprised by the quality and value for the money of recent Bachmann releases--enough so that I'm changing my purchasing habits.

Once upon a time I tried to discourage serious modelers from buying Bachmann products in a train store where I was employed...but some time ago I/we stopped laughing and started realizing that Bachmann/Kader knows what they are doing now.

Best Regards--

2-8-8-4

Thank you for your reply.

Yes there were some good people on there, too.

I will keep any discussions on here much more civil than they were there.

Best Regards--

2-8-8-4

The Atlas HO forum was once a useful forum, but has outlived its usefulness.

Don't bother to give them actual cost estimates from an actual manufacturer to build a new diesel from the ground up in the U.S.  All they do is take issue with the assumptions and the math for 10 pages while basically flaming the original poster, then they call the original poster a manufacturer's "paid shill" and/or a troll.

The high posting, highly vocal, highly critical members of the Atlas HO forum had no clue of just how much they don't know, and were very unwilling to accept any information that deviated from their personal beliefs.  

Good riddance to them!

They did more to hurt the hobby than they ever did to help it.  They demanded much greater standards of detail and prototype fidelity (that not all real-world buyers actually want) and now don't want to pay the resulting higher prices as evidenced by the plethora of topics regarding excessive price, greedy hobby shops, and greedy manufacturer/distributors.

They were utterly clueless all along, and Atlas at long last finally did the right thing by killing them off.

I just wanted to take a moment to thank Bachmann for putting out such a nicely valued loco--without the infernal traction tires--and with a very nice, though basic, sound package.  In the past I have often admired the large steam engines, but this neat little Alco 2-6-0 is just so much fun to play with on the layout...I may have to buy another!  The clarify of the chuff sound is really remarkable, as is the engine's ability to just run and run at low speed while chuffing away (in DCC mode on my MRC Sound Controller 2.0, which is not quite real DCC).

It puts some other, more highly detailed, but silent steam engines to shame...Now I may have to replace the others (I'm already in the process of paying off an EM-1 layaway).

John