2-8-4 pulling power

[Atlantic Central]

Now that they have been out for a while, I would like your thoughts on the pulling power of the Bachmann 2-8-4's.

How much have you tried to pull?

How steep are your grades?

How do they compare to other Spectrum locos you may have?

Thanks,

Sheldon

[ABC]

I tried to pull 14 NMRA weighted coal cars up a 3% grade and it didn't make it. Most of the spectrum steam engines seem to lack a bit in pulling power as do some of the diesels. Note that the 14 cars were NMRA weighted which means they were pretty heavy compared to running a car out of the box.

[lmackattack]

I just got my 2-8-4 in the mail yesterday afternoon. It is a weak puller for the size of the engine.
I could not pull more than 13 blue box athearn stock weight cars up my 2.5% incline. Off came the shell and I easly added 2.5 oz of square weights. I could add about another 1.5oz if I want but the motor seams weak and drops RPM with a good load. Currently I can pull about another 10-15 BB cars with the extra weight I added.  It will be getting a new motor that can match the weight of the locos new pulling ability.

Details are pretty good
smooth runner but the motor needs BEMF to compensate for poor starting
Headlight is too dim
runs smooth ones its moving but RPM drops easy under load
I cant use Accell and decell because of this

On a scale of 1-10 I give it a 6 mostly for looks.

Trent

[Stephen D. Richards]

Sheldon, I have three of the 2-8-4s and they seem to have the power but did need some weights for traction.  Based on your research, I can pull about 30-40 NMRA weighted rolling stock.  That is after changing the couplers, trucks, wheelsets etc.  This is on a .5 to 1.2 percent grade though.  Tractive effort does drop off a bit fast the steeper the grade.


ABC, did I miss osmething?  My 2-8-4s are not Spectrum Locomotives! They do look good though.


Stephen

[jbsmith]

I rarely go beyond 12 cars, of various types and manufacturers though i am sure it could handle more. My layout is 2 4x8s in an L shape.

A certain amount of  "how many" depends on the size and type of layout.
On a massive entire basement type layout like the ones featured in model railroad magazines the answer is "x".
I'll let someone with a massive layout like that answer that one more precisely.

If on a simple single 4x8 anything over 12 and you got what looks like a snake chasing after its own tail.

Grades?  I like level track,,just to keep things simple for now. maybe later
I'll experiment with grades. No further comments.

Compared to others, They work just fine. Break them in right and take care of them and they will return the favor.
Good Low and High speed performance even in DC.
Got three  2-6-2  Praires, one 2-8-0, two 2-8-4s.

[ABC]

ABC, did I miss osmething?  My 2-8-4s are not Spectrum Locomotives! They do look good though.

I was grouping them together, mine isn't either, it came in a blue box w/ a clear part in the front. It is pretty much the level of spectrum locos, pretty good detail, pretty decent runners, etc...
I don't remember how much weight I added to mine, but it was maybe 3.5oz (oops forgot the 3 somehow), I don't know the exact grades,  but the max was probably 3.5%, I was running it at my local club and that's why all the cars are pretty heavyweight and the grades are so steep. I could successfully pull 12 cars NMRA weighted and 1  unweighted caboose.

[Atlantic Central]

First, thanks to all for sharing your experiances.

I plan to use the 2-8-4 for a kit bash project and adding some weight is no problem as long as there is room. From everone's comments that must be the case.

My grades will not be so steep, all will be under 2%. Keep in mind that in real life a 2% grade would cut the pulling power of a steam loco to only 10-20% of what it could haul on level track.

Based on that, your 14 cars on 3% grade translates easily to 140 cars on level track.

As Stephen is aware from past posts, my cars are very free rolling with sprung metal Kadee trucks fitted with Intermountain wheel sets. That alone has increased the pulling capacity of all my locos by 20-30% or more.

Trent, I assume you run DCC since you commented about back EMF. I run DC and will be removing the decoder completely. DCC decoders do not like the pluse width signal from my Aristo Train Engineer wireless throttles.

If you are running DCC and find this or any Bachmann DCC onboard loco to not run well, consider installing a better quality decoder.

As for the comment about the "whimmpy" motor, I would tend to disagree that a "stronger" motor would be better. Just because a motor slows down under load does not mean it is inadiquite for the task. Your car slows down going uip hill until you give it more throttle? Doesn't it?

Again, thanks to all and I will continue to follow this for additional responses.

Sheldon

[lmackattack]

Hi Sheldon

I agree with you 100% about how motors will perfrom under stress. I agree a better decoder is in order and I hope that solves some of the issue.

Most of my locos if running at 50% throttle will pull my grades with about a Max loss of 10MPH,  then speed back up as it pulls the cars to level track. Currently  My 2-8-4 will start the grade with 15 cars at say 35 MPH (about 50% throttle) and then near the top it gets draged down to a full stop. wheels not slipping. I then have to give it about 20% more throttle(70% total throttle) just to get it moving again. This is a PITA if you like to use accell and decell. I add sound to all my steam engines and I think this engin would look kinda silly chuffing away with the wheels stopped

[Atlantic Central]

Trent,

I must admit I am not familiar with what you refer to as accell or decell.

Are you refering to pre programed momentum in your DCC throttle?

What brand of DCC do you use?

I don't use onboard sound and I expect to have to throttle up a heavy load for a steep grade, then throttle it back.

And, again, for me I keep grades more in line with prototype with 1.8% being about the max.

Thanks again for sharing your experiances with this loco.

Sheldon

[lmackattack]

Hi Sheldon

I am using a MRC advanced squared DCC controller.  I was refering to the Momentum settings to control the loco slowly up to speed and then slow it back down. with the factory decoder It wont compensate for motor loads. Even on the flats of my layout if the loco enters a 22" radius curve with 15+ cars it will slow down and almost come to a complete stop. then when I add throttle its to slow to add the power it needs unless I have set the momentum settings to react very quickly. at this point its no use to have momentum set as it does not work as intended.  I will have to test it out tonight at the club to see what it does on the few 1.25 grades.  None of my spectrums with factory decoders needed compensation for change in loads but they have hight end decoders with BEMF. theymay slow a little but not drasticly to the point where I need to give it another 20%  throttle. I will likely install a Digitraxx decoder tonight to see what I can get out of it. I still like this loco very much. it just needs some improvements for my likings.  

[Atlantic Central]

Trent,

OK, I understand. I'm sure this is mainly a decoder/DCC problem. As we both know, a better decoder may well make a BIG difference.

Sheldon

[lmackattack]

Update.

went to the club last night and the loco could not pull a string of 25 cars without using almost full power to get up the easy grades.  if I went below 65% throttle the loco would slow and come to a complete stop in the middle of the climb. On the flats at 65% it would maintain 50MPH.
So tonight I installed a Loc pilot decoder with BEMF and the motor control is resolved. I set the SV=1 and the loco starts to crawl even with a 25 car train. I set the momentum to the highest level and can sit back and watch it slowly pick up speed, even on the grades.  I can let the train run around at 10-20mph and it will climb my 2.5% grade without adjusting the throttle at all. This is how it should be IMO!!!

[Atlantic Central]

Thanks for the update, this confirms it was the decoder, not other aspects of the locos quality or design.

Glad you got it resolved.

Sheldon

[Atlantic Central]

Now I have a new question for the owners of the Berkshire locos.

Do any of you have the Pre Marquette versions?

If so which sandbox/steam dome arrangement does yours have and which of the two Bachmann models is it?

The catalog pictures show them to be different but the instruction sheet online shows both PM's to be the same as the NKP.

The early prototype ones on the PM matched the NKP ones, the later PM Berks matched the C&O placement.

All the shops that might have some for me to look at are an hour away, so I would like to know before I go what I might or might not actually want to buy.

Thanks,

Sheldon

[jdmike]

For a brighter and whiter headlight, pickup a package of Miniatronics Yeloglo LEDs, part number 12-310-05 3mm dia.  They are a drop in fit,  Just have your tender connected so you can make sure it lights up when it goes forward since LED'S are polarity sensitive.  You will have to shorten the leads on the new LED to match the Bachmann ones.  No soldering involved, just unplug the wires and plug them onto the new LED.  I removed the LED from the Mars light as one, it looks funny just steady lighted and 2, I plan to make the Mars Functional when I put the Tsunami in mine.   I left the LED as without it, the other wont light up.  I just put a short piece of shrink tubing over it and sealed it up and tucked it aside in boiler.   I do notice a sudden startup on normal DC, but if you gradualy bring up the power till the headlight comes on, she will start slowly.  This allows the Decoder to initilize and put power to the motor.  I will report on what extra ballest does to it.  There is room above the factory weight that is in front of the gearbox, as slippery as she is, I dont see an issue cooking the motor.   Engine is a great value for the money, its as detailed as my older PFM Brass NKP Berkshire, but already beautifully painted.    I plan to purchase a couple more to renumber.  All will have Mars Lights.    Now if I can remove the painted on duel beam mask on the headlight lense, I will be very happy, the effect doesnt work like it should and acutaly makes the headlight dimmer.    Cheers   Mike