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Improving Our Steam Engines Performance

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Posted by snjroy on Friday, February 11, 2022 9:17 AM

railandsail

Simon, look foward to the results of your experiment.

 

Ok, so here is where I am at. Digging in my junk boxes, I found this copy of the infamous Bachmann 2-10-4. This loco has a decent mechanism, but is a very poor puller. 

 IMG_20220211_094322 on Flickr

So, I added a Kato diesel mechanism (another spare in my treasure chest) under the tender shell, which turned out to be a perfect fit under the long-haul tender. The steam engine still has its original motor, I just hardwired a decoder that I placed inside the boiler. I also added Kadee couplers between the engine and the motorized tender. Turns out that I did not have to make any CV speed adjustements, both run pretty much at the same speed. I connected both using KD couplers - I'll probably remove the trip pins. They have different addresses for now, but I may give both the same address to simplify it. Not bad for a project that only costed me a decoder (30$), the rest came from the spares box. I even have sound from the tender! 

The result is a very strong puller, and a smooth operating locomotive. It needs some paint, which I will do in the next few days. The trucks on the tender are certainly not prototypical, but it will be good enough for me. I will use this loco at the club, where the hilly terrain and dirty track is a major challenge for steam operators. With both motors, I expect to pull a good length of cars. It needs a fresh coat of paint: I will post the painted version on the WPF thread when done, perhaps next week.

I'm also working on another tender using a BB SW1 mechanism. This one is way shorter and is intended to be an auxiliary tender. I am working to hide the original truck side frames (Athearn BB) with more accurate tender truck sideframes. It will be more prototypical. I will report back on that one later.

Simon

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Posted by railandsail on Friday, February 11, 2022 5:52 AM

Simon, look foward to the results of your experiment.

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Posted by snjroy on Sunday, February 6, 2022 3:22 PM

My vision would be that the original tender stays - the motorized auxiliary tender is added to the original loco+tender, using normal couplers at both ends of the auxiliary tender.

Simon

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Posted by Doughless on Sunday, February 6, 2022 1:38 PM

snjroy

Well, it could be a nice little niche market. Bachmann sells many really nice small steamers, that are poor pullers unfortunately. Instead of buying two of each, I could see someone making small motorized auxiliary tenders, with the correct trucks, in DCC. And there would be no need to remove the motors from the engines - why reduce the power? MUing would be the only thing left to do. Not a big deal really, and that would be the "niche" part of the market. And it would be totally prototypical, at least in Canada, where small engines carried their "cantines" in areas where the water was deemed inadequate.

I have many steamers that would benefit from a little push. And the added wheel power-pickup would help the older ones that have poor power pickup issues.

I will report back when I am done with my own model. It's all assembled, I just need to buy a decoder and apply a fresh paint on the tender.

Simon

 

I think that since its a niche product, it would have to be one kind of tender that fits universally behind all Bachmann locos, since Bachmann makes so many different steamers.  Hopefully, Bachmann locos all have the same draw bar and wiring plug so that the tender could hook up with any of their steamers. 

I think BLI, Athearn, Proto probably don't make enough steamers to make a universal tender a worth while venture.  

 

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Posted by snjroy on Sunday, February 6, 2022 12:49 PM

Well, it could be a nice little niche market. Bachmann sells many really nice small steamers, that are poor pullers unfortunately. Instead of buying two of each, I could see someone making small motorized auxiliary tenders, with the correct trucks, in DCC. And there would be no need to remove the motors from the engines - why reduce the power? MUing would be the only thing left to do. Not a big deal really, and that would be the "niche" part of the market. And it would be totally prototypical, at least in Canada, where small engines carried their "cantines" in areas where the water was deemed inadequate.

I have many steamers that would benefit from a little push. And the added wheel power-pickup would help the older ones that have poor power pickup issues.

I will report back when I am done with my own model. It's all assembled, I just need to buy a decoder and apply a fresh paint on the tender.

Simon

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Posted by Doughless on Sunday, February 6, 2022 10:58 AM

railandsail

 

 
Marc_Magnus

 

Massive industrial testimony of powered tender and dummy engine 

 

 

For unknown reasons it seems the use of powered tender and dummy locomotives  is not investigated neglected and  receive load of criticism 

It exist a massive industrial testimony about the use of dummy engine and powered tender for small and big steam locomotives both in N scale and HO scale 

There is no doubt possible on the fact this solution is particularly effective with really powerful steam locomotives which are sure footed and great puller in both scale.

Roco, Fleischman, Lilliput, Minitrix use this system and have produced thousands models from years of big and small steam locomotives which are fine runner and big puller and in the both scale with such approach.

Video's on You Tube attest without any doubt these locomotives run extremely fine through the sharp curves  and turnouts find on European layouts and with ease climb the big grades found on these  layouts with a big string of car behind 

In any case they pull more easily than any US model and especially compared of medium US steam like a Mikado; this is true in Ho scale and N scale 

Steam engine are dummy well weighted and have free rolling wheels, the boiler contains the electrical and electronics devices and all the wheels of tender and locomotives both side take power from the rail 

Tender allow to put big motors well geared

On US Models we have the chance to have big tender where a diesel model frame can take place including his weight quiet easily,  side bogie are easy to put from casting on the side of the powered diesel bogies, diesel from the most now have flywheel and 5 poles motors and run at extremely slow speed

The choice of model diesel is enormous and tender compatibility with a frame is an easy choice, for the most diesel locomotives pull easily 20/25 cars on level track both in Ho scale or in Nscale 

Acheiving a free rolling dummy locomotives is easy by removing motor and gear motors, tune of the side rods and good quartering do the job for sure, adding some wheight will help probably 

So far where is the disadvantage,

You can even do it with a six wheel tender bogies and put a six wheel diesel bogies a probably quiet monster pulling locomotives 

Water tender can also be modified the same way as a second powered tender to make a real steam monster puller on heavy grade 

This industrial testimony  show there is no real disadvantages of this approach and more important it could be accomplished easily on existing models with a minimum of work and need of big transformation.

very small engine are suitable for a such choice and could pull realisticaly

Let's go 

 

 

 

 

 

YES, YES, and YES

 

Nope.  It won't happen.  At least not from the North American producers.  Manufacturers score points with the buying public to make their models as prototypical as possible.  Those little wheels and sideframes on the tender trucks have to look close to perfect if they want it to sell.

They don't build product for the fantasy guy, they build them for the modeler. 

By defintion, a model is an exact replica of the prototype.  Our models have to run, so some trade offs are made, but they are still supposed to be models.

I'm not saying that it the way it is supposed to be.  Its just the way it is.

They will make them to simulate the performance of the prototype loco.  I'm not a steam loco guy, but my guess is that a model of a Mallett will pull more cars up a steeper grade then, say, a model of a Pacific.  As an example, the diesel Atlas S2 yard switcher will pull a ton of cars, but its top speed is a lot slower than an F3.

If you're asking your model to do something different....or rare....than what the prototype did, that is the root of your problem. 

You're going to have to build or modify your loco to perform that fantasy performance yourself because producers cater to the guys who want to do things prototypically.

I don't know what the European model producers design their models to do....maybe more nonprototypical things?  

Continued good luck with your project.  

- Douglas

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Posted by railandsail on Sunday, February 6, 2022 10:19 AM

Marc_Magnus

 

Massive industrial testimony of powered tender and dummy engine 

 

 

For unknown reasons it seems the use of powered tender and dummy locomotives  is not investigated neglected and  receive load of criticism 

It exist a massive industrial testimony about the use of dummy engine and powered tender for small and big steam locomotives both in N scale and HO scale 

There is no doubt possible on the fact this solution is particularly effective with really powerful steam locomotives which are sure footed and great puller in both scale.

Roco, Fleischman, Lilliput, Minitrix use this system and have produced thousands models from years of big and small steam locomotives which are fine runner and big puller and in the both scale with such approach.

Video's on You Tube attest without any doubt these locomotives run extremely fine through the sharp curves  and turnouts find on European layouts and with ease climb the big grades found on these  layouts with a big string of car behind 

In any case they pull more easily than any US model and especially compared of medium US steam like a Mikado; this is true in Ho scale and N scale 

Steam engine are dummy well weighted and have free rolling wheels, the boiler contains the electrical and electronics devices and all the wheels of tender and locomotives both side take power from the rail 

Tender allow to put big motors well geared

On US Models we have the chance to have big tender where a diesel model frame can take place including his weight quiet easily,  side bogie are easy to put from casting on the side of the powered diesel bogies, diesel from the most now have flywheel and 5 poles motors and run at extremely slow speed

The choice of model diesel is enormous and tender compatibility with a frame is an easy choice, for the most diesel locomotives pull easily 20/25 cars on level track both in Ho scale or in Nscale 

Acheiving a free rolling dummy locomotives is easy by removing motor and gear motors, tune of the side rods and good quartering do the job for sure, adding some wheight will help probably 

So far where is the disadvantage,

You can even do it with a six wheel tender bogies and put a six wheel diesel bogies a probably quiet monster pulling locomotives 

Water tender can also be modified the same way as a second powered tender to make a real steam monster puller on heavy grade 

This industrial testimony  show there is no real disadvantages of this approach and more important it could be accomplished easily on existing models with a minimum of work and need of big transformation.

very small engine are suitable for a such choice and could pull realisticaly

Let's go 

 

 

 

YES, YES, and YES

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Posted by railandsail on Sunday, February 6, 2022 10:09 AM

ATLANTIC CENTRAL

I also changed the connection point for the tender drawbar to improve overall tracking, which greatly improved tracking and pulling thru curves.

Rather than the factory connection at the very back of the frame, the loco now has a long drawbar connected just behind the rear drivers and the trailing truck is connected to the drawbar. 

These means dramaticly less side pressure on the loco as it pulls the train around a curve, meaning less flange resistance in the curve.

Sheldon

 

I will have to give that idea some considerations in some of my pusher choices,..might be very helpful?

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Posted by railandsail on Sunday, February 6, 2022 10:00 AM

ATLANTIC CENTRAL

Pretty sure I added 6 oz, and kept it balanced, without really trying too hard. bring the weight of the engine from 14 oz to 20 oz. And that seemed to do the trick on my 2% grades. Pulls more up the grade now than it did on level track out of the box. I like them so much I build 5 of them, back when you could buy the DC version of that loco for about $70.

I used all three versions, C&O, NKP and PM, and two Spectrum long Vanderbilt tenders to make three sub classes. The two longer C&O tenders are getting installed behind my two BLI N&W 2-6-6-4's that will be lettered ATLANTIC CENTRAL. I'm a little fussy about tender styles and like having a "family" look to ACR power.

Sheldon

 

Same reasoning for an individual powered reefer/express freight car to put behind our 'sub-powered/weighted', multiple selection of steamers,....rather than trying to add weight and repower up each one of them individally.

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Posted by railandsail on Sunday, February 6, 2022 9:52 AM

NVSRR

I am not understanding what he is trying to do.  I see on other forums he has pics posted and using and 80's 4-8-4.   Is he trying to remotor it?   

shane

 

I have decided that it might be a little more difficult to 'motorize' the tender on that Backmann 4-8-4 tender,..that to just put a motorized pusher (reefer) behind it. Not that it might be that difficult to do, but I would rather not do it 3 times.

That way I can use either of the 3 Northerns I have without modifying 3 of their tenders.

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Posted by railandsail on Sunday, February 6, 2022 9:43 AM

Trainman440

 

It seems his want of pulling a prototypical length train up a  4.5% grade viaduct with only one engine. Three conditions thats near impossible to meet.

Charles

 

 

I have 2 Roco steamers (BR43 & BR44) that can pull 20 car trains on those same tracks and grades without any other help.

Rather interestingly they have powered-heavily weighted tenders (no motor in the main bodies). Perhaps we could learn something from the Europeans

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Posted by snjroy on Friday, February 4, 2022 6:44 PM

Brian, I've been thinking about your idea of adding a motor under a tender. I went to a hobby shop today and I bought a BB SW1 to see what I could do. When I explained my intentions to the owner, he said that he's done this several times for clients, mostly for Mehano steamers (they made some Canadian prototypes that were quite decent looking). Got home and found a tender in my spares box that would fit - an old tender that was behind a Rivarossi Hudson. 

I'll post something if the conversion works. I have quite a few locos that would benefit from such a contraption. While I usually double-head my locos to tackle the hilly terrain at the club, some of my locos are unique and would look funny if mismatched with another steamer. Speed matching will not be a problem: I think this is where DCC can really make a difference. 

Simon 

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Posted by ATLANTIC CENTRAL on Thursday, February 3, 2022 6:55 AM

railandsail

 

 
Doughless

You can have a permanent freight car behind a tender, very unprototypically, if you want to run the layout unprototypically.  Nothing wrong with that, but one decision sort of begets the other, which is what creates the problem.

 

 

 

What about those express freight and reefer cars that were put behind the tenders of steam engines of old?

 

Yes, ok, but I think his point is prototypically at some point those cars get switched out of the train. If you are only doing display running fine.

Sheldon

    

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Posted by railandsail on Thursday, February 3, 2022 6:54 AM

ATLANTIC CENTRAL

 

 
NVSRR

I am not understanding what he is trying to do.  I see on other forums he has pics posted and using and 80's 4-8-4.   Is he trying to remotor it?   

shane

 

 

 

He is trying to make it pull a reasonably long train up a 4.5% grade - not a practical goal, repower or otherwise. The real one could not pull 20 cars up a 4.5% grade.

And to be clear, his Bachmann 4-8-4 may, or may not be that old. Bachmann did upgrade the drive and make those more recently - but they are still not very heavy or great pullers.

He refuses to provide such details about the loco.

Sheldon

 

 

BTW, the OP has NOT given up on this idea,..I'm here. I just no longer follow some subjects on this forum with regularity because of several factors such as photo submissions, lack of notification, etc.

i have been doing a little more research on this suject of a 'disguised pusher/helper freight car', and collecting suggesstions and observations by other folks. At this time i have dropped the idea of adding diesel power chassis to the tenders of that 4-8-4 northern,...just a few extra  complications that are more easily accomplished by putting an express car/reefer behind the engine.

I've also become less intested in doing a number of 'powered aux water tenders' as they would be much more rare than the express reefers.

So my concentration will be on further development of the 'powered reefer pusher',...and the best existing powered chassis to use here. And I will NOT be concerned with rivet counter details as concerns the trucks,...adds to many extra problems and BIG expenses I wish to avoid in just giving my steam engines a great extra boost without spending a fortune.

And finally I will likely have to put this project aside for awhile as I want to get the track laid on the upper level of my new layout.

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Posted by ATLANTIC CENTRAL on Thursday, February 3, 2022 6:52 AM

railandsail

 

 
selector

I appreciate all the wisdom and experience expressed so far.  It seems, as a general preference, or maybe as a matter of avoidance (due to inherent complication), that most of us prefer to run a single loco on the head end.  Due to prototypical practices, a person modeling the modern era is almost certain to want 'lashups', and that is the common practice.  We steam lovers seem to hope that our lone behemoth 2-8-2, 2-10-2, or 4-8-4 is going to do the trick, but we soon learn otherwise.

I do know that many of us doublehead steamers, and I am proud to claim that a couple of years ago I finally shoved my long coal drag, headed by a 2-6-6-4 Class A, with my trusty Y6b.  It took some fancy fingerwork, thankfully on my twin encoder Digitrax paddles, but I somehow managed to avoid a single derailment in about 10 minutes of running before the stress became too much. Confused

 

 

 

Wonder why you experienced such difficulties running those 2 BLI locos together??

 

Because he controlled them separately using the two throttles on his handheld. I have seen that done before. But when we did it on some big DCC layouts we were using pushers and two engineers. One controlled all the locos on the front, one controlled the pushers.

    

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Posted by railandsail on Thursday, February 3, 2022 6:29 AM

Doughless

You can have a permanent freight car behind a tender, very unprototypically, if you want to run the layout unprototypically.  Nothing wrong with that, but one decision sort of begets the other, which is what creates the problem.

 

What about those express freight and reefer cars that were put behind the tenders of steam engines of old?

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Posted by railandsail on Thursday, February 3, 2022 6:05 AM

Running those 2 BLI steamers together is a problem??, ....consider this....

 

ATLANTIC CENTRAL

 

 

 Why would you not simply consist the two steam locos together and run them with one throttle just like diesels

Wayne and I can tell you that in DC we have no trouble coupling different steam locos together to pull our our trains.

My favorite double headed lashups include a Proto 2-8-8-2 and a Spectrum 2-6-6-2, they run beautifully together. Or a Spectrum Heavy 4-8-2 and my Bachmann 2-8-2's (converted from 2-8-4's).

Three Spectrum 2-8-0's is really cool on the front of a train.

Two Mikados, any two Mikados, is a steam classic here in the Mid Atlantic. For 40 years nearly every B&O freight train that left Baltimore headed west started out with two Mikados typically pulling 50-70 cars.

In DC, as long as the overall gear ratio and starting voltage is similar, and the train is heavy enough to really require two locos, they generally run fine. All this perfect speed matching stuff in nonsense.

Some pulling power stats I have recorded on my layout and others:

Rivarossi C&O 2-6-6-6 - 36" curves, 2% helix grades, 90 cars.

BLI - N&W 2-6-6-4 - same layout as above, 110 cars.

Spectrum USRA Heavy 4-8-2 - 36" and larger curves, 2% grades, my old layout, single loco, 35 cars on level track, two locos double headed, 40 cars on the grades.

BLI Reading T1 4-8-4, my old layout, 45 cars, on the grades, level track about 70 cars.

Bachmann 2-8-4, converted to 2-8-2, 5 oz of weight added, my old layout, one loco, 32 cars on level track, two locos double headed, 40 cars on the grades.

The Proto 2-8-8-2 and Spectrum 2-6-6-2 combination, 50 cars on the grades.

Three Spectrum 2-8-0's, 45 cars on the grades.

No stress for me, pick up the throttle, push one button, and hold the throttle up button till it moves.........

I add about 2 oz of weight to nearly EVERY tender, for better pickup and better tracking - it is were all the pulling stress is. 

Of all the locos listed above, only the Bachmann Berk/Mikado conversions had a lot of weight added - 5 oz. I do add about 1/2 oz to Bachmann 2-8-0's in the domes, and I generally remove the pilot truck spring - yes, I remove it, and my pilot wheels stay on the track just fine.

All the others listed are dead stock in terms of weight.

The BLI and Rivarossi locos do have traction tires.

And 95% of the rolling stock have my prefered trucks - Kadee self centering sprung metal trucks refitted with Intermountain code 110 wheelsets - NO code 88 wheels or semi scale couplers.

As I said earlier, part of the secret here is large curves and gentle grades - like real trains have........

Sheldon 

 

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Posted by railandsail on Thursday, February 3, 2022 5:59 AM

selector

I appreciate all the wisdom and experience expressed so far.  It seems, as a general preference, or maybe as a matter of avoidance (due to inherent complication), that most of us prefer to run a single loco on the head end.  Due to prototypical practices, a person modeling the modern era is almost certain to want 'lashups', and that is the common practice.  We steam lovers seem to hope that our lone behemoth 2-8-2, 2-10-2, or 4-8-4 is going to do the trick, but we soon learn otherwise.

I do know that many of us doublehead steamers, and I am proud to claim that a couple of years ago I finally shoved my long coal drag, headed by a 2-6-6-4 Class A, with my trusty Y6b.  It took some fancy fingerwork, thankfully on my twin encoder Digitrax paddles, but I somehow managed to avoid a single derailment in about 10 minutes of running before the stress became too much. Confused

 

Wonder why you experienced such difficulties running those 2 BLI locos together??

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Posted by thomas81z on Sunday, December 19, 2021 4:58 PM

SeeYou190
 
thomas81z
I run all  my locos at caloosa trains & hobby shop here in cape coral FLA

 

I have been there a couple of times, but they do not stock the items I use the most. It sure is a big clean store, and I hope they are doing well.

-Kevin

 

since im the " train guy"at caloosa trains & hobby  come by sometime & let me now what you need Cool

 

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Posted by Overmod on Monday, December 6, 2021 2:13 PM

It's impossible to read half the preceding post on a phone without actually responding to it.

The 'upcoming' generation of heavy steam locomotives (stillborn after 1947) did not involve 80" drivers in most cases, as lightweight rods and better valve gear promised perfectly adequate speed.  N&W famously got 110mph out of 70", although going even a couple of mph faster was too much, not because of balancing but because of valve tribology.

Lima's answer for the future involved the Double Belpaire... which restricted driver diameter for most Eastern loading gages to 76".  Not coincidentally this was what the fearsome C&NW H dual-service engines used.

It is very important to distinguish the early crop of lower-drivered Northerns, which were like heavy Mountains in the same sort of way Berkshires were heavy Mikes, from the later high-speed engines -- the original ATSF 3751 class had 73" drivers and were relative dogs.

Below 70" you're going to be better with a modern Berk, particularly if you want heavier articulated power with a deep firebox (like a Berk-and-a-half 2-6-6-4) where you can share a wide number of parts.  But a late-'40s 69" is not the same as a late-'20s 69" either.

Meanwhile there was the duplex 'revolution' where 69" was just fine for high speed, and I suspect lower drivers would be in the offing for dual-service double Atlantic engines.  The Withuhn-conjugated-duplex ACE 3000, which was designed to run with diesels and hence have comparable top speed, was to have been given only 58".

 

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Posted by Trainman440 on Saturday, December 4, 2021 3:46 PM

ATLANTIC CENTRAL

Charles,

I'm just not up for a long discussion, but a great many 4-8-4's did not have 80" drivers. I explored this topic at great length on the TRAINS forum a few months ago.

Sheldon

I understand that. Many 4-8-4s didnt have 80" drivers, and I dont believe I ever stated that to be the case. I specifically chose 80" for my example though because the 4-8-4 OP is using, a 3776 class ATSF 4-8-4, had 80" drivers. I am assuming the OP is modeling transistion era santa fe, as he shows other santa fe diesels in pictures in alternate forums linked above, and atleast in santa fe's case, 80" drivers were standard on all 4-8-4s after 1940s. 

Im not definitively saying that all 4-8-4s were soley used for this and 2-8-2s were soley used for that, but I am making the general case (to which there are obviously exceptions). Also trying to say that the OP who wants to use a 4-8-4 with 80" drivers to pull long freight trains up steep grades is unreasonable. 

Charles

---------------------------------------------------------------------------------------------------------------

Modeling the Santa Fe & Pennsylvania in HO

Youtube Channel: https://www.youtube.com/channel/UCLb3FRqukolAtnD1khrb6lQ

Instagram (where I share projects!): https://www.instagram.com/trainman440

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Posted by Marc_Magnus on Saturday, December 4, 2021 2:12 PM

 

Massive industrial testimony of powered tender and dummy engine 

 

 

For unknown reasons it seems the use of powered tender and dummy locomotives  is not investigated neglected and  receive load of criticism 

It exist a massive industrial testimony about the use of dummy engine and powered tender for small and big steam locomotives both in N scale and HO scale 

There is no doubt possible on the fact this solution is particularly effective with really powerful steam locomotives which are sure footed and great puller in both scale.

Roco, Fleischman, Lilliput, Minitrix use this system and have produced thousands models from years of big and small steam locomotives which are fine runner and big puller and in the both scale with such approach.

Video's on You Tube attest without any doubt these locomotives run extremely fine through the sharp curves  and turnouts find on European layouts and with ease climb the big grades found on these  layouts with a big string of car behind 

In any case they pull more easily than any US model and especially compared of medium US steam like a Mikado; this is true in Ho scale and N scale 

Steam engine are dummy well weighted and have free rolling wheels, the boiler contains the electrical and electronics devices and all the wheels of tender and locomotives both side take power from the rail 

Tender allow to put big motors well geared

On US Models we have the chance to have big tender where a diesel model frame can take place including his weight quiet easily,  side bogie are easy to put from casting on the side of the powered diesel bogies, diesel from the most now have flywheel and 5 poles motors and run at extremely slow speed

The choice of model diesel is enormous and tender compatibility with a frame is an easy choice, for the most diesel locomotives pull easily 20/25 cars on level track both in Ho scale or in Nscale 

Acheiving a free rolling dummy locomotives is easy by removing motor and gear motors, tune of the side rods and good quartering do the job for sure, adding some wheight will help probably 

So far where is the disadvantage,

You can even do it with a six wheel tender bogies and put a six wheel diesel bogies a probably quiet monster pulling locomotives 

Water tender can also be modified the same way as a second powered tender to make a real steam monster puller on heavy grade 

This industrial testimony  show there is no real disadvantages of this approach and more important it could be accomplished easily on existing models with a minimum of work and need of big transformation.

very small engine are suitable for a such choice and could pull realisticaly

Let's go 

 

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Posted by ATLANTIC CENTRAL on Friday, December 3, 2021 7:49 PM

Charles,

I'm just not up for a long discussion, but a great many 4-8-4's did not have 80" drivers. I explored this topic at great length on the TRAINS forum a few months ago.

Railroads selected driver size based on application. 80" drivers, on any loco, are for speed. Here is a good comparison of the more noteable Northerns, only 4 out of 12 have 79/80" drivers:

https://steam.wesbarris.com/locobase.php?country=USA&wheel=4-8-4

The B&O never owned a Berkshire or a Northern, because their Mikados and Mountains suited their operating conditions better. Similar to the GN O-8, they did test one Mikado with 70" drivers - worked fine, just not worth the expense for their needs.

Locos you should learn about:

DT&I 800 Class Mikados - simply scaled down LIMA Berkshires.

GN O-8 Mikados - 70" driver Mikes with more power and steaming ability than any Berkshire.

B&O T-3 Mountains, 70" driver monsters that were similar in performance to LIMA Berks, and faster. 

As for my drawbar setup, yes, less side pull in curves, keeping the pulling line closer to the track center means less power loss with steam locos.

Not my idea, used on many models over the years including the Spectrum 2-6-6-2 and many before that.

Sheldon

 

    

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Posted by Doughless on Friday, December 3, 2021 5:35 PM

Trainman440
The 4-8-4 design (atleast for ATSF and NYC) were 4-6-4 hudsons with an extra driver. They weren't designed to haul freight, so maximum pulling power was a tradeoff for higher top speed and acceleration

Trainman440
The biggest difference between all these locos is wheel size, but you really cant be comparing a 4-8-4 to a 2-8-2. Its not the bigger leading and trailing truck and moreso simply just the 80" drivers (ATSF 2900 class) compared to the 63" drivers on the USRA mikado

Yes.  I should have taken a quick look at the two locos to notice the larger drivers on the Northern.  Large drivers are designed more for top end speed than pulling, relative to small drivered locos. I guess the Northern is a passenger locomotive, for the most part.  Or at least a flatlander loco.

I assume that the same basic geometry/physics applies to models.  While both locos may weigh the same and use the same motor, all things being equal, one is going to inherently be a better puller than the other simply based upon wheel size.

The prototype used a Mike to climb the 4.7% Saluda grade.  Not a large drivered loco.  But that was likely a freight route without much need for high speed passenger service.

- Douglas

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Posted by Overmod on Friday, December 3, 2021 10:32 AM

"I'm sure if someone built a 2-8-2 with 80" drivers, itll pull SLIGHTLY more than a 4-8-4 due to less weight distributed on the leading and trailing trucks, but I wouldnt think it would be a noticeable change, and certainly not a good tradeoff for the excessive weight placed on the drivers and poor handling."

A properly-designed 2-8-2 with 80" drivers would have exactly the same range of adhesive weight on drivers, the same FA, and the same effective grade performance.  The length would be shorter, although likely less than a full car, so shorter turntables could be used (as on L&N) or slightly longer trains accommodated on leads and sidings.

The weight saved matters in terms of overall train resistance, not distribution.  You would need highly effective draft and front-end arrangements, good combustion, air preheat (e.g. via Snyders) and carefully implemented external and external circulation in the radiant section to make a suitable firebox construction to run above a single trailing axle.

Of course with modern balancing 80" drivers are only needed for speeds above 100mph or more... not something most 4-8-4s would spend much time doing anyway.  Even ordinary balance allows a 74"-drivered engine nearly 100mph speed; the trouble then becoming the relatively stiff lateral required to permit near-zero overbalance in the coupled wheels as well as the main or to achieve low hunting at long cutoff...

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Posted by Trainman440 on Friday, December 3, 2021 9:10 AM

Doughless

Here's a question for steam locomotive buffs.

Was a 4-8-4 Northern designed to be a strong puller on grades compared to other similarly sized locos?

The postcard pic that I linked showed a 2-8-2 Mikado assaulting the 4.7% Saluda grade, and there is such a thing as a "Heavy Mike".

Just wondering if the bigger pilot and trailing trucks on the Northerns distributed the weight in a way that made it the inferior choice when tasked with pulling up grades.

Is the Bachmann Mike a better puller than the 4-8-4?  Maybe that's a bit intentional on the part of Bachmann?

 

The 4-8-4 design (atleast for ATSF and NYC) were 4-6-4 hudsons with an extra driver. They weren't designed to haul freight, so maximum pulling power was a tradeoff for higher top speed and acceleration.

The 2-8-2 (or 2-10-2 for that matter) was designed for slow freight drags, the complete opposite of the intention of a 4-8-4, and really shouldnt be compared. 

A good in between as Overmod mentioned, is the 2-8-4 lima berkshire, which was designed for fast freight. Not quite passenger duties (although one would suffice if needed), but the drivers were large enough for speed. This can also be applied to an extent to some mountains (such as the PRR and moreso NYC), which could handle duel service. 

----------------------------

The biggest difference between all these locos is wheel size, but you really cant be comparing a 4-8-4 to a 2-8-2. Its not the bigger leading and trailing truck and moreso simply just the 80" drivers (ATSF 2900 class) compared to the 63" drivers on the USRA mikado. 

Im sure if someone built a 2-8-2 with 80" drivers, itll pull SLIGHTLY more than a 4-8-4 due to less weight distributed on the leading and trailing trucks, but I wouldnt think it would be a noticable change, and certainly not a good tradeoff for the excessive weight placed on the drivers and poor handling. 

@Sheldon the drawbar change is an interesting concept. I wouldnt think the mounting point of the drawbar would matter so long as it is mounted at the exact height that's in line with the center of the drivers (which from your photo seems like the original Bachmann mounting spot was too high)...since otherwise the load on the drawbar will "tip" the engine forward or back and unbalancing the drivers, depending on if the drawbar is too low/too high.

I assume the new design places less "left/right" rotational force on the wheels through curves? Wonder why this isnt a more common design in RTR models these days. 

Charles

---------------------------------------------------------------------------------------------------------------

Modeling the Santa Fe & Pennsylvania in HO

Youtube Channel: https://www.youtube.com/channel/UCLb3FRqukolAtnD1khrb6lQ

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Posted by ATLANTIC CENTRAL on Friday, December 3, 2021 8:51 AM

Doughless

Here's a question for steam locomotive buffs.

Was a 4-8-4 Northern designed to be a strong puller on grades compared to other similarly sized locos?

The postcard pic that I linked showed a 2-8-2 Mikado assaulting the 4.7% Saluda grade, and there is such a thing as a "Heavy Mike".

Just wondering if the bigger pilot and trailing trucks on the Northerns distributed the weight in a way that made it the inferior choice when tasked with pulling up grades.

Is the Bachmann Mike a better puller than the 4-8-4?  Maybe that's a bit intentional on the part of Bachmann?

 

The locomotive Wayne and I are refering to is not the Bachmann USRA Mike, which I do not own a copy of to test and have not seen any feedback on its pulling ability.

The locomotive of mine Wayne referred to is pictured near the beginning of this thread and is a Bachmann Berkshire, converted by me into a Heavy Mikado similar to the prototype DT&I 800 class.

Out of the Bac the Backmann Berk is just so-so in terms of pulling ability, but I added 6 oz of weight and improved it balance which provided great results.

 

I also changed the connection point for the tender drawbar to improve overall tracking, which greatly improved tracking and pulling thru curves.

Rather than the factory connection at the very back of the frame, the loco now has a long drawbar connected just behind the rear drivers and the trailing truck is connected to the drawbar. 

These means dramaticly less side pressure on the loco as it pulls the train around a curve, meaning less flange resistance in the curve.

Sheldon

    

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Posted by Overmod on Friday, December 3, 2021 7:59 AM

The 'engine' (cylinders, rodwork, drivers) determines the hill-climbing capacity.  Adhesion sets how effectively the power is delivered to the drawbar; boiler steam-generating capacity how fast it can be done.

4-8-4s are high horsepower at speed.  For somewhat lower speed a Berk is just as good (see the L&N Emmas in particular), and a heavy Mike like a GN O-8 not far behind that.

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Posted by Doughless on Friday, December 3, 2021 7:23 AM

Here's a question for steam locomotive buffs.

Was a 4-8-4 Northern designed to be a strong puller on grades compared to other similarly sized locos?

The postcard pic that I linked showed a 2-8-2 Mikado assaulting the 4.7% Saluda grade, and there is such a thing as a "Heavy Mike".

Just wondering if the bigger pilot and trailing trucks on the Northerns distributed the weight in a way that made it the inferior choice when tasked with pulling up grades.

Is the Bachmann Mike a better puller than the 4-8-4?  Maybe that's a bit intentional on the part of Bachmann?

- Douglas

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