Author Topic: What are your thoughts on model locomotive balancing?  (Read 296 times)

tct855

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What are your thoughts on model locomotive balancing?
« on: August 22, 2017, 09:19:59 AM »
Hi glue sniffers,

My question is a curious one, but a fundamental one.

What are your thoughts on diesel or locomotive balancing, if any? If so, how do you go about balancing your equipment.

Do you feel it's important as a part of modeling? Do you know if the prototype weight balanced their locos?

I wanted to pause on my thoughts first so as not to influence your thoughts on the subject.

Thanx Thom...

Zephyrus52246

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Re: What are your thoughts on model locomotive balancing?
« Reply #1 on: August 22, 2017, 10:15:45 AM »
I've never heard of balancing model locos.  I suspect the diesels are pretty close to balanced, as they are pretty symmetric.  This goes for the prototype as well.  I suspect they were fairly well balanced otherwise the wheel wear and tractive effort would be different on each wheel.  The same would go for steam.  Our models are so light in comparison it probably doesn't make much difference.


Jeff

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Re: What are your thoughts on model locomotive balancing?
« Reply #2 on: August 22, 2017, 11:07:39 AM »
Loco balancing? Let me see, you are really bored aren't you friend?

I can't speak for all railroads but the Seaboard, Atlantic Coast Line and Florida East Coast at least made an effort to "balance" the motive power.

Typical would be ABA, ABBA, AA or other combinations.

However, toward the end of the "Fallen Flag" era, railroads pulled any thing that would work.

The SAL, regeared RS-2's to pull local passenger trains.

I've seen FEC Geeps sandwiched between E units.

Towards the end any combination of locos were used and the Hell with the balancing. If the gear ratio fit, it was in the consist.

Tom ;D
If you hate plan A, you are certainly not going to like plan B!

Tom Langford
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tct855

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Re: What are your thoughts on model locomotive balancing?
« Reply #3 on: August 22, 2017, 02:08:55 PM »
Great answers all,

Hi all,
    My discussion thoughts were more to, when building an steam/diesel loco other than a solid cast.

How do you like to balance out the model (equally over the drivers on steam) and (between the trucks on diesels).

Especially since Dcc sound with all the extra electronics take the place of the once fully loaded with weight spaces.

Yes the prototype have to take into consideration the weight to horsepower ratio, on both steam & diesels.

Are we modelers aware of this? or is it a part of model building that we know how to or even care to resolve?

If you're asking what it is or why? Then I ask, have you noticed why your plastic steam engines have rubber tired drivers or why you need (3) 4 axle diesel engines to pull a 25+ car train, When one 6 axle engine does it with no problem?

or Why your engine pulls better in one direction over the other? or Slips a bit when pulling slow over switches?


I'm curious what others do? or Think about it?  Thanx Thom...

7thStreetShops

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Re: What are your thoughts on model locomotive balancing?
« Reply #4 on: August 22, 2017, 04:49:54 PM »

This is an interesting and somewhat complex subject (far from boring) that involves not just weight but suspension as well! It's also one of those lost arts of model railroading.

Balancing a model locomotive can and often does improve a poor puller (I'm talking primarily steam engines - I've never encountered a particular problem with disease-als but then I'm not a disease-al fan either.) I balance locomotives when someone is "aware" enough to ask for it or if it is apparent the loco is woefully out of balance. Balance is often "modified" unintentionally thru the process of repowering where a large inefficient motor is replaced with a smaller one that is powerful but may have half the weight. Or when someone either forgets or fails to realize that slug of lead is important! (Sacrificing weight for DCC is not very wise.)

Rigid couplings are pretty easy to balance compared to articulates but neither is particularly difficult if you are set up for it. The process involves a balance beam and some means of conveniently placing weight on the exterior in order to achieve the right balance - and no a perfect balance is NOT correct. The engine should be slightly heavy toward the front. In the end a little knowledge, patience, and a bit of time is what is required.

Once an engine is balanced it is also a good idea to make sure all drivers make good contact with the rail. It is not uncommon to find center drivers floating. This commonly means incorrect springs were used by the manufacturer - or "others". Good suspension means all wheels keep good contact even over less than ideal track.

Now a little testimonial;

A client had a high end PBL K-36  (Sn3). Very nice model but it would not pull more than about 8 properly weighted cars up his 2% helix. Not really bad for a model but less than the prototype was well capable of. So he sent the model to me and I balanced it (and probably adjusted the springs iirc). When he got it back the engine would pull 18 cars up the same grade! No, I'm not exaggerating.

Balancing is expensive to have done by a professional because it is time consuming but it is a practice that can provide striking results.

Most models are woefully under weight. But simply tucking weight where ever it will fit isn't always a good practice.

bparrish

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Re: What are your thoughts on model locomotive balancing?
« Reply #5 on: August 22, 2017, 04:50:32 PM »
Thom..

I hope I am understanding what you are referring to with balance.

First for Diesel models.  I suppose you are talking about weight balance end to end.  That is easy to check if you have a digital postal scale.  Set up some sort of block of wood or the like and put one truck on the scale and the other on the block.  The idea is to have the loco level so there is no weight shift to the lower end.  Note reading and turn around the loco.  If you choose, you can add a small amount of weight to the lighter of the two. 

As Diesel models do not have any differential device from truck to truck, the wheels are all turning at the same speed even if one truck is slipping.  It is not like a car where one side can over speed in relation to the other like when driving on ice or snow.

For steam this can be a real issue.  If the weight bias is too far apart you will find the loco wants to derail more easily in one direction than the other.  Boiler weights were usually chosen by the manufacturer to off set the weight of the magnet in the open frame motors. Recall that the magnet was always in the rear of the cab over the trailing wheels ( if the loco has them at all ).  When remotoring to cans, that weight in the front becomes dominant for several reasons.  First, can motors are usually lighter and further, the weight is centered on the motor, not at one end.  Additionally, we tend to set the motor closer to the gear case, thus moving in the weight toward the center.

I would not advocate  removing boiler weight but rather add a small amount in the cab to attempt to maintain the original balance of the loco.

There is another issue with steam locos that most operators don't think about. That is springs added to pilot or trailing trucks.  Those springs help keep the small wheeled trucks on the track but at the expense of the tractive force of the drivers.  The stronger the springs, the lighter the drivers become.  Similarly, uneven springs front to rear (on a 2-6-2 for example) will shift the weight on the drivers to the opposite end.  For example strong pilot spring will shift the weight to the rear drivers.  Consider the opposite to be true of the trailing spring is stronger.

There is a point of diminishing returns by adding weight to any model loco. Add weight, more tractive force. With that however, goes heat at the motor due to increased current applied to the motor to get things going and keep things going.  Hills and tight curves turn up the load on a loco as flange friction goes up in curves and hills are obvious.

More later.
Bob
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bparrish

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Re: What are your thoughts on model locomotive balancing?
« Reply #6 on: August 22, 2017, 05:12:18 PM »
To continue...

The post above mine from 7thstreet shops may be another person as it does not carry a name but.......

The page for the person does show Hamilton Montana. This may very well be Dave at NWSL.  If it is in fact Dave,  he has a huge amount of knowledge on this subject.

Thank you for your input.

To continue with another idea of balancing has to do with consisting locos. 

Two Diesels may have the same motors and all sorts of stuff from the same manufacturer but they may run at different speeds even if the same data is applied to the decoders via JMRI programing.

I know of a modeler here in downtown Idaho who speed trapped his locos and dialed the acceleration tables on his decoders.  This allowed consisted locos to do different things even though a single notch speed was interpreted by both decoders.  He could turn up the distance per 15 seconds at a set speed to conform with the speed of the consisted loco.  His pulling capacities are huge and all locos are extremely quiet if the sound is turned off.

For consisting of steam another issue must be considered in addition to the stuff noted above. That is, weight  of the tender.  I have an e-mail out to Didric Voss (NMRA standards guru) to get his thoughts on this.  But.......  The tender of a consisted pair of steam locos must be of enough weight to resist jack knifing.  It is one thing for a tender to have enough weight to stay on the tracks and following NMRA weight standards for rolling stock is usually adequate. But....... again......... The tender of the lead loco is not expecting to be pushed on from the rear. Thus jack knifing is a real possibility.  Adding weight is a solution to a point but again there is a point of diminishing returns.

Great conversation.
thanx
Bob
All it takes to start and insane asylum is a big room and the right kind of people.

7thStreetShops

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Re: What are your thoughts on model locomotive balancing?
« Reply #7 on: August 22, 2017, 06:52:27 PM »
bparrish, 7thstreetshops is Derrell Poole. Dave does indeed have a great deal of knowledge.

7th Street Shops is the sole repair contractor for NWSL and has been since 2010. Most of my efforts there is in model mechanism repair and improvements but I also contribute to many of the repower kits they offer. 7th Street Shops is a full service company with its own merits as a custom full service shop as opposed to NWSL's mechanism focus. I rarely if ever balance an engine under the NWSL banner. (Note that under either banner we never take plastic , rarely take diecast, and work almost exclusively on HOsg and larger BRASS.)

Your comments on tender weight are thoughtful and useful. I've not paid much attention to consisting issues but appreciate your thoughts. Tender weight is also important in the sense that good pickup is important especially with DCC. I've seldom found problems with drawbar connectivity if the drawbar is properly installed (spring side up) but wheel pickup issues are relatively common. In my opinion the issue of balance of the drivers is a viable answer to a "heavy" tender as opposed to lightening the tender when the engine pulls poorly. This includes attention to the suspension.

I'm not too worried about overtaxing a motor that is of the proper size (torque capacity) to begin with. The motors we use are very high efficient with the 2032D-9 nearly bullet proof. You cannot add enough weight to the typical HO engine to truly destroy it. Well, perhaps in some cases but you will likely break something else first.

I installed one of these motors in an NWSL 2-6-6-2 and while on the bench test running I noticed after a while the front truck was no longer running - but the rear truck was. The assumption was the coupling shaft had come out of place or a cup was slipping. Nope! The front gearbox worm had stripped the teeth from the axle gear (of a brand new box) and kept on going! The motor, of course, was nevertheless happy and running cool and fine as if nothing had happened. So I replaced the gear, thought I'd fixed the cause of the "jam", and ran it again. Amazingly enough it did it again! I fixed the gear a second time and did find the true cause of the jam. So far as I know that motor with 2 gears under its belt is STILL going. They were BRASS gears! Not plastic!

I've coupled pairs of 2032s in S scale D&RGW Tunnel motors with no sweat. Current draw less than 1 amp.

For disease-als with 2 axle trucks the NWSL Stanton Drive is a boon! I watched an HO scale SD run for several days with about 1/2 pound of weight stuck to it and it never broke a sweat. That motor was a tiny 1220D-9. The advantage of having the power in the truck under the model is that the shell is empty and you can add as much weight, interior detail, and DCC as you want.

The Stanton Drive is an amazing product. I've seen them installed in a model creep at 2.25 inches per minute! More than once customers have reported how (for instance) the dinner bell rang, they thought they shut the power all the way down only to come back later and the engine was GONE! They eventually found it somewhere on the layout still creeping away because the power was NOT all the way off.

So motor overheating is not really so much of an issue as it once was. 

bparrish

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Re: What are your thoughts on model locomotive balancing?
« Reply #8 on: August 22, 2017, 08:43:54 PM »
Derrell....

Welcome to the forum. Your knowledge and experience will be well spent here.

Regarding the brass gears running out....... I remember in the 50's when Mantua came with a plastic spur gear and they said that industrial plastics could wear out metal........ will I remember my BS detector going off at the time.  Since then I have seen numerous Bowser brass gears run out on their black ascetal plastics on various trolleys.

I am sold on the Stanton drives and have put them into many trolley box motors and steeple cabs.  They are bullet proof as you suggest.  The only thing I have redesigned on those is that I hide the motor pins on the PC board with epoxy due to derails that might put the motor onto the rail and put DCC input to the motor side of the decoder..  I talked to Dave some years ago about this and he seems to be much closer on trimming off the pin but as yet has not covered it with anything.

Dave is a great resource and he has bailed me out on a lot of weird things with small brass locos.

Again............. welcome aboard.

see ya
Bob
All it takes to start and insane asylum is a big room and the right kind of people.

tct855

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Re: What are your thoughts on model locomotive balancing?
« Reply #9 on: August 22, 2017, 09:43:40 PM »
Hello all,
   Let me also un-simply say- I agree with both Derrell & Bob's points of model locomotive balancing.  I've balanced the models I do by the scale/block method (in early years before the digital scales I did Derrells string/platform method.

As part of my services when I work on all models I always try to balance out, adjust springs, check for truck articulating-swivel-tilting, both front/rear pilots (if applicable), drawbar tension/radius bend, wire tensions, and properly weight tender from consist and tracking.

I know it sounds (reads) like a lot , but it's all tied together to achieve a proper smooth responsive running artistic device. ( said all that so I can justify my kidney stone painful rate for my services). ha. teasing folks.

Think of all the complex parts of a complete layout- benchwork, structure bases, subroad beds, trackage radii, switches, wiring, Dcc power district's, signals, structure lighting, all the individual structure parts, glues etc, etc, (see I can go on with the everyday layout/structure shhhtuff as easily as we loco gurus go on about engines.  ;D

It's all good. People forget, model railroading teaches a lot of beneficial aspects as a whole which is what I think contributes to this "World's Greatest Hobby".  Thanx Thom...

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Re: What are your thoughts on model locomotive balancing?
« Reply #10 on: August 23, 2017, 07:44:15 AM »
Well,  I certainly missed the boat on the balancing act. Otherwise, Bob, Thom and Derrell have covered the subject quite well.

There are probably only four of us here that can properly address this issue and three of them have already spoken. I have nothing else to add.

Just saying.

Tom 8)
If you hate plan A, you are certainly not going to like plan B!

Tom Langford
telsr1@aol.com

7thStreetShops

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Re: What are your thoughts on model locomotive balancing?
« Reply #11 on: August 23, 2017, 11:36:38 AM »
I'm sure Thom will come up with another boat, Tom. Get to work, Thom!

 

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