Large Scale Central

USA Trains SD40-2 Experiences

General Discussion
#1

After working on a few USA Trains SD40-2 locos with 3 axle trucks over time, I finally completed a vignette (article) about experience and methods for removing / installing things and fixes.

Back in 2012 I got my first new Southern Pacific SD40-2, and then last year I got a used Union Pacific unit that had just the body shell and chassis with no detail parts and having been stripped of its trucks. Having got the parts needed, it’s now put back together in operating condition - shown below with substitute hoses from a GP38 - SD hoses not being available.

Then, I remedied a friend’s Southern Pacific unit that had been modified for battery operation but suffered from “wet noodle” chassis syndrome that flexed too much for changing to body mounted Kadee center set knuckle couplers.

Now chronicled in new vignette,
“USAT SD40-2 Experiences, including Kadee centerset couplers” - and a whole lot more!

It’s Contents includes:

Overview
New Southern Pacific SD40-2
Optional Snow Plow
Union Pacific SD40-2 Reconstituted
New Motor Blocks
Sideframes
Wheels & Traction Tires
Truck Assembly
R & R Body Shell / Chassis
Chassis Dog House
Switch Board & Cables
Motor Current In-rush Resistors
Kadee Centerset Coupler & Box Choices
Installing CamPac BoxesTM
Installing Datum Precision Metal Boxes
Installing CamPac Pilot Plugs
Installing Detail Parts & Railings
Installing Extra Weight
Comparison of USAT SD40-2 & Aristo SD45
Battery & “Wet Noodle” SD40-2 Chassis Fix!
Videos

I hope the vignette is useful to somebody, it took weeks to compile - comprising of 70+ illustrations, most populated with 4+ images, totaling more than 300 pictures.

-Ted

#2

Ted Doskaris said:

I hope the vignette is useful to somebody, it took weeks to compile - comprising of 70+ illustrations, most populated with 4+ images, totaling more than 300 pictures.

-Ted

Ted,

I personally enjoy ALL your documentations and totally respect the TIME you and many others have put into making them !

#3

While some of the things you do probably i will never try, I have learned a lot from all your articles and genuinely appreciate all the time and effort you put into these.

#4

Thanks for a lot of information on the SD40-2’s.,Ted D.

I been wanting to get back on doing some minor checks and cleaning on my three SD40-2’s and do some investigating on drives.

I’m using D/C power to our layout. I see you show using a inline Wire wound Resistors to each the motor blocks and I would like to be able to run them with my GP38’s and GP-9’s.

Ted D. have you done any trial and error on this? Was thinking a 2 or 3 ohm @ 10 watts but not sure on this do to the difference size wheels.

I know we may lose a little bit of pulling power on each SD-40-2’s but can make it up with adding the Geep’s. Noel

#5

Thank you Noel and every one else.

Noel,

I don’t think you will have a problem running your SD40-2 with Geeps just they way they come from the factory.

I use DC track power, too, but often use it in PWM mode and do with the SD40-2. Because of using PWM, I added one ohm resistors (as done and described by George Schreyer on his website) to prevent wheel pitting on my USA Trains Geeps, F3s as well as well as the SD40-2.

The Geeps tend to run a little fast in my opinion, but not a big difference that would prevent them from working with the SD40-2 -with or without them having resistors installed.

The tests I did with the SD-40-2 with resistors that still run faster than the real slow Aristo SD45 operated Okay when MUed. The reason is when the locos are MU together along with pulling the weight of a train they tend to equalize in that the slower loco may draw slightly less current with the faster loco drawing slightly more current. As an added fail safe, I replace axles having traction tires with ones having solid wheels. This has 2 benefits:
Wheels are allowed to slip so back emf is generated for less current draw of the “faster loco”,
(and for track power users) additional electrical pickup area from the railhead is afforded. If needed, “MUing” another loco makes up for the pulling ability.

All that said, I can try a specific, run together, test to see how a Geep/s or F3/s (that use the same 2 axle motor blocks) run with a SD40-2 with its 3 axle motor blocks.

-Ted

#6

Thanks Ted. I can’t use the PWM on my throttles do to, i use my signals off of track power and need them to show bright signal going in the right directions on low start up voltage. Its for some guy to see when that block are turned on in block area.

We are using three and four throttles sometimes.

I did use the PWM for switching task at low real low speed and it worked well, but then came the signals for block and to save a lot of wiring I just taped off the rails for them.

Ok on the SD40-2’s, They do ok with long trains but kind of buck a little with just a few cars so may still mess around with some Sand Wire wound resis. Just to see if i can slow it down a bit.

Course… i have two darn U.P.'s and only one S.F. warbonnet. I like to get all S.F stuff so may trade off the U.P.'s before i take them apart yet.

Thanks for the comeback Ted and you every have a chance Like to meet you up here sometime when all of the virus crap is over. Noel.

#7

Hi Noel,

Thanks for the invite to see you and layout. From pictures of it I had seen over time, it looks to be really impressive.

As to your SD40-2 “bucking”, I don’t think adding resistors will help. The motor blocks each run independently from one another (no interconnecting drive shaft like on smaller scales) so if one is somewhat “out of tune”, that’s the reason for bucking. As to using the resistors for better matching different loco speeds, the GP38 runs slightly faster than the SD40-2, so the resistors in series with its motors may help in this loco to slow it bit if you want, but I don’t think it necessary.

To see how “Geeps” operate with the SD40-2, I ran my 25 car train (previously shown in a video) but now with the USA Trains SD40-2 coupled to 2 USA Trains GP7/9s.(These Geeps use the same motor blocks as the GP38, GP30, and F3s)

All 3 of my locos have the one ohm resistor in series with each of their motors, my intent being to mitigate wheel pitting when operating PWM track power. Since all 3 of these locos have the resistors, then one can deduce, if they all did not have the resistors, performance would be similar except for the slight speed difference.

A new video (better seen on YouTube for setting resolution to 1080P and description) shows the successful operation of the 3 locos pulling the train on the layout.

-Ted

#8

Nice work Ted and great video…

#9

Thanks Ted for the video…Sure helps … Very interesting.

So looks like I see here around 10 USA Eng to install 1 ohm @10watt Resis. Boy…That a total of 40 Resis.'s to put in-line for the motor blocks.

Willl give it a try and we may not have to re-program the Sierra Sound cards with only 1 ohm lost.

Guess we are still kind a the old ways here…lol.

Kind of wish we started out with Kadees and R/C Receiver for each Eng. unit but started out 1998 using 5 Aristo R/C units. . With all of the guys in our Group, most only had D/C track power Eng. to Trains to run here. But a few did have a few Batt guys tho. Also,most of us use USA or Bachmann rebuilt Couples here.

Nice layout to watch, Ted and thanks for taking time to make the video to see how your s run. Noel.

#10

Noel,

The resistors are in the motor path, not the power pickup path, so when properly installed, they will not affect other things like your sound system.

I am not convinced that you need to use the resistors in your Geeps with the intent to more exactly speed match with the SD40-2, but if you are going to do this, see vignette, “GP38, USA Trains GP38 … and various mods”, Appendix A - Motor current in-rush resistors.

Shown there will be two ways to add the resistors: One with a toggle switch so in one position the loco operates as factory intended and the other position so they are engaged. I only did one loco with the switch, so it’s simpler to just wire in the resistors with no switch, and that arrangement is also shown by scrolling down to see it.

-Ted

#11

How does PWM cause pitting on USA GP/SD wheels?

#12

Bill Sakalaucks said:

How does PWM cause pitting on USA GP/SD wheels?

Wait, I know this. I just watched a video this morning that mentioned that.

http://www.girr.org/girr/tips/tips11/wheel_pitting.html

#13

Thanks Ted. Ya… I met to say just ahead of the motor blocks. Should not be any change in anything else. I have most USA’s with DP/DT Sw. for running in Rev. when adding Eng’s for the sound cards only. And yes one SD40-2 have 3 Ohm @10 W…Sand Wire Resis. for to work with Geep’s and F unit now and seems are working fine now with our T/M’s Throttles ok. So far a good match in all speeds with load on no load.

I didn’t read all of the Appendix A. but we have like shown… changed out all lamps to LED’,s and whats nice is when climbing our 2 % grade, I have to add more power to keep up with the speed to keep up and sound card goes to next notch and really sound great. Same as coming down grade by going over Mag the Reeds kick in Dym Brakes and notches down.

Pitted wheels…Don’t seem to see any but we do use WD-40 to help clean the Pine sap off the rails and Wheel get lub I guess. Most wheels on Eng and Rolling stock look like new on most. but on Bachmann stuff is a difference story… I thing they come pitted… lol.

Guess you have to see our operation here when can …Lot difference using reeds and block that we have to go the with the trains or some times trains just gets lost and have to use the intercom’s with others to find out where they are or routed/wait 10 min and hope it show back up. lol

Course do the the weather and things with Jane, Layout is in a need of minor repairs and clean up. Darn layout grew to much over time.

Anyway …this is very interesting talking to you and seeing the other side. Noel

#14

It’s all good pap!

(https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)

#15

Noel Wilson said:

SNIP"…one SD40-2 have 3 Ohm @10 W…Sand Wire Resis. for to work with Geep’s and F unit now and seems are working fine now with our T/M’s Throttles ok. …" SNIP

Noel, Please correct me if I misunderstand, but from what is described above, resistors were used in the SD40-2 to slow it down to run with your, or other folk’s, Geeps & F units.

To clarify, the way the USAT SD40-2 and Geeps & F units come from the factory, the SD-40-2 is the slower of the locos when running them separated on a track. If resistors had been put in the SD40-2 to slow it even more when run with the Geeps & F units, this is backwards to what factory units do! In this regard, something else must have been done to alter all or some of those locos.

Thank you,

-Ted

#16

Ted Doskaris said:

Noel Wilson said:

SNIP"…one SD40-2 have 3 Ohm @10 W…Sand Wire Resis. for to work with Geep’s and F unit now and seems are working fine now with our T/M’s Throttles ok. …" SNIP

Noel, Please correct me if I misunderstand, but from what is described above, resistors were used in the SD40-2 to slow it down to run with your, or other folk’s, Geeps & F units.

Ted…This is correct… our SD40-2’s have larger wheels , approx…1- 5/16" and is a faster unit that our GP’s and F units with smaller wheels. 1-1/8" on the rails.

The SD40-2 will walk away from the GP’s with out the Resis.

Sorry if i was confusing on what i said on ours posts. Noel

To clarify, the way the USAT SD40-2 and Geeps & F units come from the factory, the SD-40-2 is the slower of the locos when running them separated on a track. If resistors had been put in the SD40-2 to slow it even more when run with the Geeps & F units, this is backwards to what factory units do! In this regard, something else must have been done to alter all or some of those locos.

Thank you,

Ted

TED. Not sure on your statement of SD40-2 running slower. Ours run faster than Geeps and F units…

Is it something to do with PWM and Remote Rec. installed in your units and maybe the difference gear set up that changes when not using Straight D/C track power like ours? You are showing it the other way around?

Our SD40-2’s has the floppy front wheel drive and maybe older verson?

"Other problem may be… we are Santa fe warbonets with one SD and with two other U.P’s (YELLOWS SD’s that don’t match our SF. ) that should don’t belong on our R.R."LoL

SORRY on S.F. HAD TO PUT THAT IN THERE. LoL. Noel

#17

Noel, thanks for the feedback, and I do believe your experiences. Why we differ is puzzling. I did do a speed test and video recorded it yesterday using two GP38-2s and one SD40-2.

Illustrated below is the setup where I ran the locos in different operational modes on a track circle that will be shown in the video.

Based on the tests done using the example locos, the video with descriptions demonstrates that the GP38-2 runs faster than SD40-2 (unless that GP38-2 has the motor current in-rush resistors in series with its motors).

I think the video is best viewed on YouTube so you can set the resolution to 1080P and see the written description in “show more”.
Video: “USA Trains GP38-2 & SD40-2 Speed Differences”

-Ted

#18

Hey Ted. Great Video and love the tech information…I’ll have to get my scope out to and do some tests. The way your test works on any way you run them, they seem to be ok usable together with any difference medications. We only have a few Gp’s and F units and all three Sd-40-2’s with still have rubber tires on them. So will do some more test at our set up bay and see if can make a video of what ours is doing. I have one SD40 that will walk away from the Geeps and now a have a resis in it to run with others

Kind of wish we could go with the PWM but have Sierra sound that operate off the track voltage for the difference sounds on most of our USA Eng’s.

Again, Thanks for making the video and chasing it in circles for us…laf.

As …old K6WGZ-6, it nice to see the tech side with you. Now have to later on when I have more time, get my scope out and trace out my problems and see what’s going on. .

Good test, Ted.

Noel