Allegheny(s)

Yesterday I was running some experiments with running a few Rivarossi Allegheny locos around the recently new loop of the bottom deck of my layout. I had advertised 1 or 2 in my inventory for sale. I had some questions from potential buyers about their running qualities. I also wanted to satisfy some of my own questions about their pulling power.

The 'test track' is my newly laid code100 atlas track around the perimeter of my 12x16 foot train shed. Regrettably it is not all level track, but rather rises at a grade of about 3% (edited; looks to be closer to 4%) on a stone arch viaduct that covers much of the trackage. This makes things a bit more challenging, but its about the minimum grade I could use in my relatively small layout. My trains are going to have to run this grade, both while circling the bottom deck, AND when entering the helix structure for a trip to the top deck.

...before the track was laid
 

This is just 2 of the Alleghenys I was playing with, one is my most treasured one with heavy weathering, and the other a more lightly weathered one. ( I also discovered an electrical pick-up problem on one of the others, that I documented over on another subject thread).
 

BTW, none of my Alleghenys have the optional traction tires..

I dragged out some misc freight cars I had, choosing those that had metal wheels. I was real surprised at the wheel slipping I experienced at the top of the grade with only 9-10 cars in tow ! I subsequently added some weight to the locos (1oz,.. then 1.25 oz) and that improved the situation. I'm not so sure I could fit much more than that amount of weight into those boiler shells, so I didn't bother to go further at this time.
 

Is my track grade really affecting the pulling power of these big locos that much??

EDITED: The grade looks to be closer to 4% upon re-measurement

IHC Mehano 4-8-2 Mountains

I happen to have one of my trusty old Mehano mountains sitting around, and decide to give it a go at the same load. It pulled a little better and slipped its wheels less. Then I added a little weight to her and it got better as well.

I don't think I would have much trouble adding this much weight to her boiler.

sacrilege...ha...ha

Okay I am a committed steam engine fan. But I just might have to modify that some.

I took 3 different diesel 6 axle engines (individually) that I had sitting around and hooked them up to that same freight car group I had been experimenting with. They pulled that group around like with EASE,...no slipping, just plain easy uninterrupted running !.

I guess I can see how these younger folks go for the diesel engine power....wow.

Tungsten powder or or very small shot added to the voids.

remove the shells of the loco's and add tungsten powder or small lead shot to voids, and fill those voids with epoxy to seal the weight in.  Also check the balance of those locomotives.  If the loco's are front heavy, thin sheet lead added to the inside of the cab roof, or some brass figures of engineer & fireman added to the cab will move weight rearward.  Just make sure when you add weight that the drivers will still slip if the loco stalls.

weight and traction tires

My 2-6-6-6 is similarly handicapped. It seems to be able to get about 14 cars up a 4.2% grade. (These cars are Accurail with metal wheels and are very close to NMRA weight standards.)

Broadway Limiteds and (generally) Proto 1000's have a lot more weight. The BLIs often have traction tires too. The BLIs can usually drag away anything we can assemble in the yards. At the club a BLI 2-10-4 took 38 cars up a 5.3% grade and almost certainly could handle more as there was not even a slowdown. A Proto 1000 DL-109 took over the same train and also handled the grade.

Bachmann Spectrum 2-6-6-2's are a little better than the Rivarossi 2-6-6-6 - they can do almost 20 up the 4.2%. (18? 19? can't remember for sure.) A Stewart C630 is about the same. A pair of Atlas TrainMasters can handle 55, but appear to be on the edge.

I should point out that although I'm disappointed with the 2-6-6-6, all the others are more or less OK. The 4.2% is on my test layout, intentionally steep precisely because it's a test layout. The real layout is limited to 3.5%, and moreover, passing sidings limit train length to 21-22 cars plus power, so anything that's around 18-20 at 4.2% is likely to make the grades at 3.5% with 22.

Traction

You may have just discovered why on slopes geared locomotives, like Shay's, Heiser's, Climaxes, and Willamettes were preferred over rod locomotives. Your diesels more accurately mimic the geared locomotives drive train over that of the Alleghenies and Mountains. Smaller wheels, fewer of them, equals more tractive effort for the power. 

Or so it seems. 

The simple answer is yes

Grade is a big player in how many cars a train can pull.  The draw bar force required for a given train goes up because part of the car weight is added to the level surface draw bar force.  The amount of force the engine can pull is reduced by a portion of the engine weight.  

Another player is the resistance of the track work.  Specifically here it is the sharpness of  the curve.  I do not have it handy, but there is relationships that equate effective grade for various curve radius.  I believe a 20 in radius adds the resistance equal to a 1% grade.  Resistance here is another form of draw bar force.

The basics are that there is a certain external draw bar force level that will trigger wheel slip.  This is a partial slip condition.  The engine will continue pulling more force after this point. the engine speed drops as more force is required.  Notionally when no more pulling force is produced, the wheels are in full slip.  Other factors seem to have some impact here, but that is the fundamentals.

The force level when the slip occurs is influenced mainly by the force the wheel perpendicular to the track and the surface roughness of the wheel & the track.  

The perpendicular force is the engine weight divided by the number of wheels in contact.  This is why the engine weight is important.  Adding weight increases the force values above by the delta weight times the coefficient of friction, with is in the neighborhood of 0.3.  

The surface roughness works on the coefficient of friction part of the resulting force.  This is where traction tires come into play.  Depending on the material of the TT, this factor can approach 0.5.  That is a 66% increase per wheel for the same engine weight.  While that sounds impressive, traction tires have a limited functional life.  Before they break entirely, they pick up oils & dirt that effectively reduces this coefficient factor.  Changing them on steam engines is a real pain.

As with everything, the devil is in the details.  In general the more contact surface area, the more force should be produced.  More wheels driving then should produce more force & thus pull more cars.  This is only true if the wheels have equal contact force.  The reality of three points make a plane tend to work against that objective.  The trucks of a diesel tend to be at the ends of the engine and our models free to pivot.  Thus each truck has three contact points that are in full contact.  The amount of contact of the others is dependent on how they are held relative to the plane.  

In the case of steam engines, the drivers are held in place by a frame that does not have much ability to pivot on the track imperfections.  So even if you have eight drive wheels on both a diesel & a steam engine, The diesel should have six points in full contact where the steam engine only has three.  Yes the other wheels are providing some force, but you can see potential issue here.

Another factor in this is the weight distribution (balance).  The typical steam engine has the drivers close together more or less in the middle.  If you were to put the weight on one end, the number of full contact wheels could drop to two of less.  The non driver wheels would take the rest of the weight which is not good for pulling force.

Articulated steam engines should buy back some of the contact points, depending on how flexible their frames are.  the forward tends to float where the back is fixed like the non articulated

As indicate above, in general an engine with 12 drive wheels should pull more than an engine with 8 for the same weight and wheel surface conditions.  

There are other factors that also seem to have an impact, but that is more detail than I think you want.

Locomotive (Steam & Diesel) Pulling Capability Tests

"EUREKA!" My new "Bull-Frog (Snot)" - arrived in the mail today (10/21/21), & I will apply this the my H-8 2-6-6-6 loco from Rivarossi, that is missing the traction tires, & won't pull its weight, out-of a wet paper-bag! I'm referring to the 2002 release that was reviewed, & incorrectly the author stated it had (one), 1 traction tire...which according to the review, the loco would pull ~120~ free-rolling freight cars, on level track...

"NOT Bloody Likely"...I say!

Cheers

AL

@AL

Yes Al,  I read that review and wondered how much payola the guy got paid for that glowing account....ha...ha.

I just got a link to a traction tire source that sounds very promising (on another subject thread). I would also like to find a source for a set of driver wheels that would make use of traction tires.
 

I seem to recall having an articulated engine in the past that had traction tires. It piulled like a bandit. i think I sold it off looking to move up in details on the locos.

Track Work Clitch

So I am having a little fun finally running a few trains, but of course another little track work glitch shows up. Its where I might have suspected I was going to have to do some 'fine-tuning' to do , but it was a bit more involved than I first thought. I discovered it when I was hot-rodding a Proto 6 axle diesel around the loop.

It continuously derailed as it hit the straight portion of track after coming down the other side of the stone viaduct. I was surprised as 3 of the other 6 axle diesels I had run thru there had no problem? It not only just derailed, it flipped over on its side !...was it a double grade junction problem, a problem with that loco in particular, or something else.

Long story short I had to spend considerable time (over 3-4 hours) placing various number of shims, and various thickness shims under the rails at that junction,...and tacking down the track firmly to get the best grading of the 3 tracks and the mainline track. I chose to place the shims under the ballast cork.

you can see all the white shims....at first I thought it was going to be more,...and thicker ones. I made great use of a 36" alum measuring stick laid on its side atop the railheads to make sure I had the mainline track purely level before I tackled the viaduct track entering the equation.

Its working real smooth now. And in fact the transition grade is less abrupt which is allowing my Genesis loco with the too-low snow plow to go thru was well. All is well that ends well.

Glad I found this now as otherwise it will be hard to reach behind the big coaling tower.

Bachmann Mountains

I have a soft spot for the Mountain locos with the flying pumps and plumbing on their boiler face,..and vandy tenders. So not only do i have a few of those IHC Melano versions, I also have a few of the Bachmann versions. Lets give one of those a try.

It also had some sound. It turns out to be quiet a good puller,...bested the IHC one with the added weight, and the Allegheny. With some fine tuning and proper lube after its very long storage time it probably will be better.

Lets say I am happy with its performance. Weathered up these are going to look super!!...and I have enough of them to run double-headed often.

My 4% Grade

My grade on this viaduct structure was dictated by my need to be able to run double stack container cars under neath and into my central peninsula,...

So I am stuck with this big grade (BTW the grade in my helix is only 2 -2.5 if I recall properly). I believe my solution is I am going to have to operate double-headed engines very often. I'm OK with that,....besides it looks neat.

Double up these guys and I will really be able to pull some long trains,...at least long in terms of my small, tight radius layout.

Is the grade your

Quoting local grade or an average for the climb?  The average is limiting, unless there is a local spike.  Double heading should allow some head room for up to 15 car trains.  
 

For your steam engines, it would be interesting the know a weight of the engine minus the tender.  With that plus the number of traction tires it would help understand what your seeing.  
 

Pardon my continuation with

Pardon my continuation with this subject thread, but its been so long (years) since I was able to run some of my trains. I'm just taking a break from electrical wiring to run a few, (and test my track work on this lower level).

Previously I had experienced a derailing event with a Proto 2K 6 axle diesel. I had recently purchased a used Proto E7a and not test run it. Lets see what it will do. Put it on the track, turned up the power and got lots of sound but almost no movement. I took it off the track fearing it might be suffering from that hardened grease problems that plague these P 2K locos.

Later yesterday I decided to check the lube in the trucks, and found them to be clogged full of grease, some of it hardened. Cleaned it all out, and put it back on the track. Again it was NOT moving out right way?
Got the instruction manual out that came with the loco, and discovered it had a QSI decoder installed in it. That decoder is programmed to start engine up realistically, so one must leave the power on the loco for awhile before movement takes place,...and one should not use excessive power too quickly.

Bottom line it is now running fine,...and it pulls a good load of cars,....and it does not derail on my tracks. Happy,...and I learned something about these decoders.

Russian Decapod

I had another small steamer I had bought recently at a train show, and had not run it yet. I needed to make a few detail repairs to glue the stack back on, and some railings on the tender.

Got it without any identifying box, and subsequently discovered it was a Bachmann loco. It had marvelous detail under the boiler, and at one point I thought the motor unit was down at axle level
 

That sort of detail could rival brass locos?

The big surprise was the operating smoothness of this engine !!....and a steamer at that. I subsequently discovered that this is one of those belt-drive locos that Bachmann came up with. I hope there other belt drive locos work as smoothly?

A word of caution

A word of caution when adding weight to some steam locomotive.  If you add too much weight in the wrong area you run the chance of throwing the unit out of balance or collapsing the spring if equipped. 

I have a very close friend who took his brass steam locomotive and filled all the voids with low-temp solder.  Well you can guess what happened.  He collapsed the springs in the drivers and messed up the balance of the unit.  It took me over 4 hours to suck all the solder out of the unit.  All this because it would not pull like a real one.

Good luck.

Andy H

Minooka, IL

2 steps forward, 1 step back

I recently moved on to putting buss wires into my outdoor/outback helix, and hooking up a few of the feeder wires. All of a sudden I am experiencing some sort of short in some of the helix tracks (measuring zero ohms/resistance  across the 2 rails of a singular track).

These particular helix tracks are the ones that will carry the trains between the upper and lower decks. They are destined to be a portion of the power district on that right hand side of the bottom deck. I've looked and relooked at the small number of feeder wire hook-ups I've made since beginning this wiring,...and I can NOT find any short wiring.

And what baffles me is that just a few days ago I was running trains around the whole bottom level,..with NO  problems at all,...certainly no indications of a short !!

I guess I am going to have to isolate these helix tracks from the other lower deck tracks, and see if I can find the fault that way. What a way to deflate my joy of running those trains.

I hate wiring !!

...

The bigger problem with adding weight to those Rivarossis is that they Will overheat and the motor is in the center of the boiler.  This will lead to melting the boiler shell, I have seen more than one like this.

This will lead to melting the

Are you speaking of having seen Alleghenys like this??

...

Mostly Challengers, but they all have the same internal design (Rivarossi articulated locomotives).  Don't run your Rivarossi too long or too hard.

...

I purchased this unit cheap as is with the thought I could do all sorts of things with it - the tender and engine beds would be among the best parts Rivarossi ever made in terms of finish and detail.

Here's the damaged area with a little magnification.  Saving this boiler shell was basically a no-go and the boiler shell itself may or may not be the same design as their earlier boilers, and even if they are, the level of detail on these later editions would have meant a lot of work to make things look like they did once before - only the risk of this happening again would still be there.

I have long since sold off this unit because there were two roads in the forest and I decided to lighten my load and let this unit take the road I didn't travel.

I probably should have saved the tender.  Eh!  :S

@Benny

Thanks for that contribution,...definitely something to keep in mind

And what baffles me is that

Hallelujah  !!, I found my electrical short,...in the helix,...just a singular mis-wiring of one of the feeder wire pairs. But it sure took a lot of time and investigation to find it.