# GP38-2 slowing in curves



## Steve G (Jan 28, 2009)

Hi All,

First timer here. I am trying to run a USA GP38-2 on an LGB starter set layout. The GP38 slows to a crawl with the lights shutting off in the curves. It doesn't pick up momentum again until completely out of the curved section. On the straights it does okay, but still not as well as I'd expect. St Aubin's thinks I have too small of curves but I see others here have run on the same size. 
My layout:

Approx. 10 x 10
5' diameter curves
LGB 50171 transformer

Let me know if any other info will help in addressing my concern. Thanks.


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## aceinspp (Jan 2, 2008)

Steve welcome to the forum. My guess is the power supply is not big enough to operate the train as USAT locos draw a lot of current when running the lights smoke and such. Are you sure of the curve size? To sharp and they can bind the loco also. Later RJD


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## Steve G (Jan 28, 2009)

Thanks. I am positive about the curve size. It came with the Pennsy Forney set. All my LGBs run smooth and nice on it. I have just encountered this problem when I purchased my GP38-2. Any idea how many amps I would require? I only plan on running a single engine with maybe a lighted caboose. Any cars (moste likely 3 or less) would be unlighted.


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## smcgill (Jan 2, 2008)

Yes it sounds like you need more POWER!!!!!!!
Just ask Tim the Tool man!


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## Randy Stone (Jan 2, 2008)

Hi Steve

When a locomotive is sitting on a straight pc of track, basically the only thing the motor has to over come to start moving is the weight of the locomotive and what ever it is pulling or pushing.

The electric motor or motors in the locomotive draw current/amps dependant on the load present.

When the locomotive enters a curved pc of track, the locomotive wants to go straight. The flanges on the wheels rub the inside of the outer rail of the curve and this guides the wheels around the curve. The flange of the wheel pressing against the rail causes friction and thus extra load on the electric motor. This causes the electric motor to draw more current/amps from the transformer.

Now, the tighter the radius or diameter of the curve is, the higher the friction will be and the higher the current/amp draw will be.

So, while the LGB starter set transformer may provide enough power to provide the current/amps to run the locomotive on straight track, the transformer most likely doesn't have enough power to provide the current/amps to supply the locomotive while under additional loading caused by the flange pressing against the rail.

Check the Current/Amp capacity of the transformer and then find out what the current/amp draw for the GP38-2 is.

Good Luck

Randy


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## Steve G (Jan 28, 2009)

Thanks Randy,

That makes sense. Unfortunately I am too much of a novice to know much about electricity. All I know about the transformer is what is printed on it:

Input 120VAC 60HZ
Output 20VAC 28VA

Does that answer the transformer capabilities? After googling, people refer to it as a 1 amp transformer.

I do not know what the power draw of the locomotive is. I have googled that, and can't find documentation, nor did my loco ship with any paperwork. 

Another concern I have, is the capacity of my wire to the track. It is LGB wire 51230 and it is listed as 2 x 1.5 mm squared. Should I be concerned about how many amps I run through that?


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## chuck n (Jan 2, 2008)

The engine may be too large for the curved track that you are using. Are you sure you are using 5' diameter curves? LGB starter sets usually come with 4' diameter curves. Look on the back of your curved track and see if it is 1100 series or 1500 series. The 1100 is 4' diameter and the 1500 is 5'. In order to get the engine to run properly you will probably need larger diameter curves, 1600 (LGB) which is about 8' diameter. 

It doesn't sound like it's a transformer problem. There is a thermal circuit breaker on most LGB transformers. If the transformer is overloaded it will cut out completely and only restart when it cools down to close the switch. That engine has two motors unlike the forney which has only one. You will over load a starter powerpack with a two motor engine. It may take a while to heat up, but it will.

Chuck N


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## Steve G (Jan 28, 2009)

Thanks Chuck,

Sorry if I am a little slow, but what is your advice? Should I upgrade my power supply to a bridgewerks or something similiar? 

I am sure about the curves. I can't see the underside since they are nailed down, but I have 4' curves to compare with, and the ones on my layout are definately 5'.


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## lathroum (Jan 2, 2008)

OK... I am the KING of small curves... I run indoor... and for a while all I had was 4' diam curves...

Only this past year did I upgrade my outer loop to 6.5' Diam, and my inner loop to 5' Diam...

Sounds like a power issue to me... as I had no problems with my GP38-2, GP7/9, RS3, U25B on 4' diam Curves...
There are some mods that need to be made to keep from pulling cars off the tracks, but I have not found a 4 axle loco that
won't go around 4' diam curves... I'm not saying it looks pretty, but they will make it...

I have a few of the LGB starter packs, and they are grossly underpowered for anything but the locos they come with...I use them under the christmas tree only...

The Bachmann Starter packs are just as bad, if not worse... I use them to power the lights in my buildings... so I can dim/brighten them as I want...
They also make good paper weights.... and good fodder for kids science projects...

The Aristo starter packs are pretty good... I still use one on my inner loop...
I was just running a NW-2 and a GP7 doubleheaded... won't go too fast but it works with lights (no smoke)
It will overload if you try to go too fast, but I run more prototypical speeds through my layout... with one loco they are fine...

I suggest getting a larger power supply... buy something big/nice, you'll need it later anyway...

Philip


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## Steve G (Jan 28, 2009)

Thank you Philip, 

It is good to get confirmation that the curves aren't the problem. Did you catch my wire question a couple of posts back? I am considering the Bridgewerks mini mag. Thoughts?


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## aceinspp (Jan 2, 2008)

If your going to up grade the power supply then up grade the wiring also. I still would double check the cure of the track. Later RJD


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## Randy Stone (Jan 2, 2008)

Steve, I would upgrade the wire size also. I would use 12 gauge stranded wire. Bridge Works should be able to tell you what size wire to use also 

Just to let you know, I use a MRC 6200 Transformer rated at 60 VA 

Randy


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## Randy Stone (Jan 2, 2008)

Steve 

Also, before buying the MiniMag, consider what your long range plans are. If you plan to run more than one locomotive or have 200 feet of mainline track, the MiniMag might not be enough transformer. So, if you can afford a bigger transformer, it will be cheaper to buy it now than have to purchase another bigger one later. 

Randy


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## Steve G (Jan 28, 2009)

Randy,

That is good advice, but I have some constraints that limit my ambition. I am running indoors in a bedroom, so I only have about 40 ft of track. Plus, being indoors I am a little scared of having so much power. I currently have my LGB wire running through the wall. If I could manage to stay within the restraints of the wire, it would save me a good amount of time and money. I am well aware, this may not be possible.


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## George Schreyer (Jan 16, 2009)

Most USAT locos tend to be current hogs and are probably a little much for your power pack. The USAT locos will run on 4' diameter curves but they strain to do it and look terrible at the same time. Wide is better, but it sounds like you need a bigger power pack most urgently. 

BridgeWerks is pretty expensive. Look to a 10 amp Train Engineer and an Elite 3 voltage power supply. You'll get plenty of current capability for less $ than a BridgeWerks AND it has a walkaround throttle as well. 

- gws


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## Greg Elmassian (Jan 3, 2008)

The LGB transformer indeed has an output of 1 amp, way too little period. 

You don't need to worry about more amps, it takes higher voltage to kill you, due to the resistance of your body. You could hold the leads of a 12v 10,000 amp power supply in your hands and suffer no ill effects. This is because current flows based on resistance... your body resistance is much higher than the motor of a locomotive. 

This is a common misconception. Now voltage is different, it is always there no matter what the resistance (unless you draw more current than the power supply can provide).. in that case voltage drops... and it's this case that is probably happening. The LGB unit is probably operating at max load, but not really sensing a short. 

Get a better power supply first. I would recommend the MRC Power G, 10 amps, and inexpensive and works well. 











I have had problems with the "lighter weight" MRC units, including the 6200 (Which could not supply enough current for my LGB track cleaning loco).. 

Regards, Greg


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## Dan Pierce (Jan 2, 2008)

A 2 amp power pack should meet all your power needs if limited to 2 motors (single engine with 2 motors like the GP-38) or a small powered engine with powered tender. 
Adding passenger cars with lights could tax this setup. 

Since you are indoors with small/tight curves, the bigger engines with more current draw can not be run like SD-45's, dash9, PA's. 

Of course, if you try to tun 2 gp's, they will not run unless you go to more current.


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## Dick413 (Jan 7, 2008)

Hello Steve
On George Schreyer's web site he states that a GP 7 will spike over 8amps
and they have the same motor as the 38 , I also read some ware that they pull over 2 amps normal.
Go to George's web site lots of good info


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## Greg Elmassian (Jan 3, 2008)

You need to look at the average current. 

I can get about 1.7 amps continuously working my USAT locos with 2 motors hard. 

1 amp no way, 2 amps will be just enough, but you will be dead if you have lighted cars with bulbs (some of my USAT streamliners draw over an amp each!). 

I would not scrimp. 

Regards, Greg


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## lathroum (Jan 2, 2008)

I scrimped for a while and ran with just the Aristo starter packs...

they are enough to run 2 locos with lights... or one with lights and smoke...

I finally got an Aristo Ultima... and WOW what a difference...

I should have done it years ago...


Philip


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## K27_463 (Jan 2, 2008)

Greg Wrote: "but you will be dead". Probably a poor choice of words to someone without understanding of electricity  

Jonathan/EMW


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## Steve G (Jan 28, 2009)

Hello All,

I just wanted to thank everyone for their help on this thread. I finally had enough time this weekend to re-wire my layout and hook up the new MRC Power G. With that everything works swimmingly! Plenty of power for everything I own. Thanks again, you guys are an asset.


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## Greg Elmassian (Jan 3, 2008)

Great stuff Steve, glad it was something as simple as we first felt. 

I think you will be happy long term with your MRC, it's doing a great job for me. 

Regards, Greg


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