Need Help with PS2 Roller Modification

I understand specific models that had issues, and also the manufacture mistakes during assembly.

You shouldn't apply an isolated issue to the overall design.  Though that happens on this forum all the time.

A premier Hudson I just upgraded has all 2 right side drivers connected buy wire.  Same with 2 left.  The trailing truck had double axle wiper via wire directly to drawbar.

Tender chassis had each truck with double wipers wired into the board.  So lots of redundancy.

But if that was not on early or certain models, or blacken non conducting screws were used there certainly could be issues.

There also is the track/switch issues.  Some track only has one rail grounded, others have issues with their switch continuity.  Most operators for example apply jumpers around any atlas switch.  After that mod they don't seem to have issues.

I got it that if your 3R only you would rather simplify the engine to maximize it for your operations.

But the 2R guys/gals and those that swing both way with different clubs get one engine that can work in any environment.  With PS-3 you now have the ultimate 2R/3R DC/AC DCS/DCC/Conv capability.  And they don't have to make 5 versions of the same engine.   G

George,

Very nice summation!

Sam, that is what I was thinking and is where I'm currently stuck. There just doesn't seem to be an easy way to shift the rollers. Only thought that comes to mind is to fabricate a custom roller pair with different leg lengths. Not something I'm enthusiastic about.

Scott there's a lot of good advice on this thread, I'm saving it!  Two thoughts:

(1) Did you thoroughly investigate that the ground side isn't the cause of the problem?  The notion of touching a grounded wire to one or more of the wheels when the loco is stalled seems like a convenient, safe way to check this.

(2) Some years ago MTH diesels had only one roller per truck.  I'm not sure when the change to double rollers occurred.  Normally two rollers are better than one.  But...IF the bracket length of the single roller assembly is different from either of the existing brackets on the double roller, then substituting the single roller assembly on one truck will change the spacing and solve your problem.

As far as whether any single roller assembly is a bolt-in replacement to your current-production truck block, perhaps George (GGG) or one of the other MTH techs could say, and also provide a part number.  A more expensive fix would be to exchange the whole truck block with one from an older diesel.  Again this will only work if the bracket length or angle is different.  Don't give up!!  -Ted

Ted, I'd take that one step farther and using an insulated probe, poke the center rail power over to a roller and see if that wakes it up.  It should be easy to determine where the issue lies.

These rollers came from my MTH Premier 2R SD70ace. It looks like they can be squeezed into your truck with minor work and will increase the spacing...I think.

You really can't modify the roller inside the truck opening.  Your confined and have to account for the roller to move vertically.  Also, you don't know what your drilling into to add a second screw hole.

As far testing for continuity, I would avoid probing under the engine.  Remove the shell and run the test.  When it stops, turn off track power and touch a probe to the 7 pin connector black wire to out side rail and the red to center rail.  One of them will be an open.

But I think Scott already has determined the pickups are on dead spots based on length between rollers.  G

You shouldn't apply an isolated issue to the overall design.  Though that happens on this forum all the time.

I agree, GGG, but in this case I think it was a design error, or at least a fabrication error.  It would only show up if one runs a loco slowly (<5smph), and over a non-derailing switch where uneveness in the trackwork would cause a front driver to lift off the powered rail. Most operators will not encounter it.  It happened on only one of my 50+/- switches.

The center drivers won't contact the rail when this happens and the rear drivers are insulated from the frame for some reason (wheel rims are insulated from the axle; maybe the Chinese mfr used 2-rail wheels there).  While the front tender truck has a wiper, it was not wired to anything.  BB pooh-poohed my problem until he encountered it it, and his trackwork is far better than mine.  My solution had been to run a wire from that tender wiper to the loco frame.  BB refined the solution to running a wire from the wiper to the tender frame.  I switched to his solution, and have had no problems since.

Ted may have a valid point, about trying single rollers.  My BL2 has singles.  But my btruck may be different.  I's post a photo but I'm away from home today.

Do you have a picture when it is stalled with the engine rolled over part way?

It would allow us to see the trackage in the area of your issue.

7 ohms is not a good connection FYI.

John and Lima,

Here is a quick update. I did find a way to add a roller to the forward truck by replacing the electro coupler with a standard coupler and adding the roller under the standard coupler. And it worked! . . . well, sort of. It did get through the roller spacing section without trouble but got hung up other places it should not have where rollers are clearly in good contact with a hot rail. I had removed the silver metal spring bars from both trucks while I was installing the roller so maybe that's the problem. Will replace those and try again.

One thing to note about this engine is that it appears to have been sitting for a LONG time. There are little bits of rust here and there and other evidence of age although it appears not to have been run very much.

To John's comment, the 7 ohms didn't strike me as very good either. So I keep coming back to that mess of wires connected to the 2R/3R and DCS Polarity switches. I honestly can't see anything wrong with the switches unless it's internal. Corrosion or oxidation maybe?

Will report back later. Will also re-read all of the other posts on this thread a second time and trouble shoot the possibility of bad contact at the wheels.

One way or another I'm gonna fix this d@mn thing! Thanks to all for the help.

S

Make sure you have a good fluke that can read 0 ohms.  Start at red wire on 7 pin connector. Or jump the nickel screw at the roller to the red wire in 7 pin.  Should be 0 ohms.

I have seen rollers that look good with heavy corrosion inside the roller at pin.  Kills DCS signal and can cause continuity issues.

Just move from point to point and see if you get a high resistance area.  G

Success.

As shown in the photos below I added a forward roller under the forward coupler shaft and swapped out the electro coupler for a standard coupler without the thumbtack section. This solved the rail spacing problem but I still had stalls where I should not have. Per some of the advice above I verified that I did indeed have a bad common connection. After the engine stalled where it should not have I connected a wire to a section of outer rail and touched the other end to one of the ground wheels and boom, the engine came back to life. At the time I did this check I had removed the silver 2R/3R metal springs bars and pins under both trucks so I replaced them just the way they were before I removed them. Still had the problem. So I removed them again and replaced this time installed the little pins under the spring the way you see in the second photo. Note that the little button pins are installed to bridge the connection from wheel to wheel. That just seemed like a smart thing to do. So, GGG and GRJ . . . what does this say about the 2R/3R switch? Is it bad??

FYI, engine runs like a dream now except for an oscillating squeal in reverse??

And thanks again for the help!

Scott,

I'm glad you are up and running.  I think all too often we assume that the ground must be good due to the fact that there are so many connections on a loco.  I has become the first thing I check.  Especially with the newer engines.

Dave

Well, you can assume that there is some issue with the 2-rail/3-rail switching circuitry or the wipers on the second set of wheels. 

Scott, Sounds like the truck ground assembly was not assembled correctly.

To test the switch check the switch pin in 3R position for 0 ohms.  Then check left wheel to right wheel.  Sounds like the wheels were not conducting to the ground wires because of the brush/spring contact on the axle bearings.  G

GGG,

Could this have been an engine repaired or rebuilt at some time? When I added the engine to DCS, no information (name, type, number) came up on the display. I had to add it manually. Also, the engine sound is identical to a PS2 GP9 that I have. I would have expected a different and unique sound for a BL2. And then there's the smoke output. Good grief I've never seen anything like it from a twin stack engine. It almost blows the shell off! It's something of a mysterious engine. As I said, if you search eBay for MTH BL2's you'll find plenty of PS1's but no PS2's. So it's rare in my book.

S

This was cataloged in 2006 and Imperial Trains, PA is still on shown on the locator as having one.  Rarity... 

Wow, that's amazing! I called and they said only two of these were ever made. They have one and I have the other one. What are the odds!?

http://mckeencar.com.340elmp01...2&docsearch=true

I find it hard to believe only 2 made, but...  The above link is MTH BL2 offerings page.  The shot is from 2006.

Yes some one could have changed the board.  Does it have a production sticker with engine name on it?   Usually on PS-2 relay.  G

Just having some fun with Charly  To her point though, the jokes on me if I spent 3 years on and off waiting to find a used engine and some shop back east has a mint item in stock . But hey, but mine is the only one existence with 5 rollers.

Glad to hear it was only a ground/common issue. Is the squeal from a pick up roller?