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Aristo GP40 problems - Smoking motors & Dehabilitated wheels!
Ted Doskaris
January 19, 2010

I currently have 8 Aristo-Craft GP40 locos. I got most of them in 2008. I did get an additional Rock Island GP40, road number 395, late in 2009.

I like the GP40s as they are nicely detailed locomotives, and when I first operated them they ran well, were very quiet, and drew little current.

For an overall description, see "Aristo-Craft GP40 4 axle locomotive vignette" .

However, as time progressed problems started to arise. One of them developed total motor failures - which makes one wonder if and when some of the others may eventually do the same.

Since I currently have about 50 various locos (48 Aristo), many are not run that much until some passing in time. Also, being distracted for the last few years on house construction projects has delayed train running some, too.

For those GP40s I have with enough run time, they suffered from degraded wheel surfaces adversely affecting track power operation. But run time on these was only within about 100 laps on my under house layout - having then noticed wheel problems.

The following is a description of the problems:


Motor block shorted power pickup wires:

Rock Island GP40, road no. 392

The GP40 motor block has four wires with two black wires dedicated for power pickup originating from the wheels that contact the rails. The motor block wires pass through a rectangular slot in the loco's chassis. The chassis is plastic, but the interior upper part includes a long metal channel.


When the truck pivots, the motor block wires can rub on the metal edge of the slot within the upper part of the loco as shown below:


This resulted in smoke and melted insulation as the conductors within the two black wires apparently made contact with the metal that shorted the power picked up from the wheels.


Ultimately the 10 amp fuse was blown in the track side Train Engineer receiver.


(By happenstance, the loco's poly fuses were of no protection as the truck with the shorted wires was not in their electrical path for this circumstance.)

Though the slot in the metal section is larger than the plastic slot - a good thing - it became evident that this is inadequate to prevent the wires from abrading as I found the metal edge to be rough to the touch.
When the wires move back and forth against the edge as the loco truck pivots it's only a matter of time that they are sawed through. Depending on how the wires may be dressed, it would seem other locos would be similarly jeopardized.




To prevent the wires from abrading again, I used duct tape wrapped over the edges of the slot as shown below:
A more professional fix may be to use something like "cat track" to surround the edges.



Failed motors:

I typically run two or three locos coupled together to pull a train on my layout.

In the case of two relatively new Aristo Rock Island GP40s, I had two of them running together pulling a train from time to time.

Since I have about 50 locos, the run time on many of them is not particularly much even though I may have had some for a long time.

Anyway, the Rock Island loco previously described with the shorted power pickup wires eventually suffered from two failed motors in rapid succession. The motor blocks actually emitted smoke as they drew excessive current!

At first impression one would think it had to do with the shorted power pick up wires, but this was not the case. If anything, shorting the power pickups would somewhat emulate what the over voltage protector IC provides in the way of protection by shunting current across the motors.

In this regard, the GP 40 includes a "surface mount" IC device (SMA33JC Transient Voltage Suppressor) in each motor block on the underside of a little circuit board. See below picture.

The SMA33 TVS device specs. include a nominal breakdown voltage of 33vdc and maximum surge current of about 8.5 amps. See below link for download of example Ltie-On Semiconductor company data sheet.
http://www.datasheetarchive.com/pdf/Datasheet-018/DSA00314743.pdf

Having electrically isolated the trucks from the rest of the loco, it became evident the motors had failed in of themselves.
Shown below is the truck all by itself resting on a wood block with power connected along with oscilloscope probes on each of two electrical leads.


Shown below is an Aristo-Craft Train Controller with Pulse Width Control (PWC) that I purposely limited in its voltage output at about 10 volts.


The oscilloscope display below shows the PWC voltage peak to peak value, pulse duration and rate of occurrence.


The analog ammeter shown below can't follow the PWC waveform as seen on the 'scope - so it "smooths" its reading to steady amount of lesser value than what would be a peak current draw during the pulse time. Even so, the current reads an excessive 2.4 amps with the truck wheels suspended in air and slowly turning!

If left in this condition for very long, the motor would become hot and start to smoke.
I later isolated the motor all by itself, and it made no difference in its ill performance.


As to why the motors failed, it seems the windings likely shorted, but what would have caused this to happen is undetermined at this time. The shorted power pick up leads previously described cannot cause the motors to fail.
It's possible to speculate that the motors suffered from a manufacturing quality issue, were the wrong ones installed by the factory, or not made to the proper specifications. In any event, an incoming inspection process common to many companies would be expected to catch these issues before product reaches its customers.

To Aristo's credit, they sent a "call tag" for the motor blocks and returned motor blocks with working motors. Aristo indicated they had to order 2000 motors, so understandably it did take some waiting, but given a commitment to such quantities I must not be alone with failed motors.


Wheel problems:

GP40s within a 100 laps around my layout

The plating wears off the wheel treads very rapidly resulting in excessive electrical arcing and black carbon and / or copper oxide deposits on both the rail head and wheel tread surfaces.





The below picture shows a close up example of the back deposits imbedded in the area of the wheel tread's pealed-off plating!


It got so bad that the loco operated in a jerky fashion and finally stalled as it became insulated from any power pickup from the rails!

To illustrate, I placed a machinist scale touching against the stalled loco's wheel and rail in an attempt to provide a current path ....

... and sparks resulted (shown below) as the loco jerked into operation for a split second.



Removing wheels from an Aristo "prime mover" diesel type motor block.


If you have a set of replacement wheels, the following describes an example method for properly removing the wheels.

For the GP40, the truck / motor block can be left in place as there is no need to remove it; however, the side frames must be removed. They are held in place by 3 small vertically located screws for each side frame. The tops of screws that attach to the motor block "fingers" can be seen in the below picture.

With the loco securely placed upside down, remove the 2 small screws in the lower part of the side frame. The upper most screw only needs to be backed out so it can be left in place. The side frames can then be withdrawn away from the motor block.

WARNING! When removing the wheel/s do not attempt to pry them away from the motor block as you will certainly damage the gear box half shaft retaining mechanism.[/b]
The wheels are held in place on a tapered axle hub with a small screw and external tooth lock washer.

A wheel puller should be used to remove the wheel/s. In so doing, do not completely remove the screw that retains the wheel but back it out some so as to leave somewhat of a gap.


Though there are various small wheel pullers made or self made ones, I use a Craftsman brand automotive battery terminal puller having spring loaded jaws that just happens to be ideal in size and shape for pulling the wheels.

By opening up the jaws just a little, the puller can be slid over the upper part of wheel then downward until it is about even with its center.
(If you try to open the jaws all the way and approach the wheel head on, there is not enough room to do it this way.)

The Craftsman puller happens to have a conical like recess on the end of its rod / shank that is ideal for enveloping the head of the wheel hub's screw so when tightened down it won't slide off.


Once the wheels are removed, you can see how the axle hubs have a taper to them.



Replacement Wheels

Not all Aristo-Craft diesel wheels are the same. The example shown below on the left is the ART-29130 replacement wheel meant for the motor blocks used in the likes of the FA1, RS3, U25B, RDC, Eggeliner, etc. locos that have ball bearing axles.
If you attempt to use this wheel on the GP40 or any other diesel "prime mover" era gear box loco (e.g. SD 45, Dash-9, E8/E9) it will wobble (along with changed back to back spacing) as the wheel differs in its hub taper and, also, does not include the ridge on its backside hub area.

The intended Aristo brand replacement wheel to use on the GP40 appears to be part number P29355-22. The GP40 wheel is shown on the right in the below picture.


The Aristo "On-Line Store" link for the P29355-22 is shown below at the price of $12.00 for a single wheel for the diesel prime mover type locos.
https://www.aristocrafttrainstore.com/scripts/cgiip.exe/WService=takestock/itemdet.html?itemnum=P29355-22&conum=001
On the other hand, the "On-Line Store" link for the ART-29135 shown below is at price of $17.00 for a pair of wheels, and these are assumed to be the wheels for the diesel prime mover type locos. So the pair is the better value.
https://www.aristocrafttrainstore.com/scripts/cgiip.exe/WService=takestock/itemdet.html?itemnum=ART29135&conum=001

Aristo has yet to publish an "Exploded Parts Diagram" for the GP40 that would show definitive part numbers, but the diagram for the SD45 that uses the same wheel (at $10.00 each) identifies it as ART-29355 - or is it P29355-22? What adds to the confusion is the Aristo parts diagram for the Dash-9 (that also uses the same wheel) describes part number ART-29355 for the entire 3 axle motor block assembly at $95.00.
Moreover, the "ARISTO- CRAFT TRAINS ON HAND AS OF 12-15-09" includes
"ART29355 MOTOR BLOCK 3 AXLE DIESEL (EA) 153.00".
See below link.
http://www.aristocraft.com/instock/instock.pdf

So the ART-29355 must be the entire 3 axle motor block.

See below link for Aristo Technical Support, Exploded Parts Diagrams of Aristo locos.
http://www.aristocraft.com/techinfo/pdf/index.html
Note the disclaimer statement at the bottom of the "Technical Support" web page may explain all!
- Caveat Emptor.


Comments:

Since the wheels used on the Aristo GP40 two axle motor blocks are shared with Aristo's 3 axle motor block locos (SD45, Dash-9, E8/E9), one would expect them to share the same problems as previously described, too!

To wit, my SP SD45 has the plating significantly worn off some of its wheels - mostly on the rigid axle of each of its motor blocks. In this case the center axle's wheels.

Note that subsequent production runs of SD45s have the rigid axle moved to either end of the motor block with it finally being placed at the location nearest the pilot ends of the loco.


However, since the 3 axle motor blocks have more wheels available for power pickup from the track rails, these locos seem a bit more forgiving. That said, my SP SD45 has now become intermittent in operation, too.
Though it took a much longer time for this unit to become dehabilitated compared to the GP40 examples, it may be that the Aristo factory wheel quality has degraded, too, since the SD45 was made in prior times.

This has become a significant dilemma to confront. Though Aristo may be able to supply replacement wheels, it seems using them would likely be no different in quality than what is on the GP40s as previously described!
Moreover, at the present time aftermarket wheel suppliers such as NWSL and Gary Raymond no longer make / choose not to make / or don't make a diesel SD45 / GP 40 loco wheel.

I know that some folks will suggest using battery power as an alternative, but I don't choose to do this for operating multiple locos pulling long heavy trains; aside which, battery power is not germane to this discussion other than to ascertain if loco wheels have their plating worn off when not being used to conduct power from the track rails.

More to the point, it is a reasonable expectation that good wheel quality be a given for any manufacture to provide to its customers - particularly since track power products are the typical standard offering. In this regard, Aristo-Craft had considered making stainless steel wheels awhile back but evidentially decided not to do so.

-Ted
 

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Houston. We have a problem. Better spike that Kool Aide with some consciousness suppressant.

Mr Polk is famous for saisfactorily fixing AC problems. Expect no less.
 

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Ted, thanks for the info and the heads up on the GP-40. I have two that I run on track and battery power. I'll be sure to correct the sharp edges when I have them open to install REVO and install by-pass wiring for battery MU operation. As far as the motors, if they go, they go back to AC. Thanks again Ted, that was alot of work for an excellent post. The GP-40 is a great little engine
 

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Thanks so much for your post, it seems to comfirm what Nick said in another thread about these locos. I was on the fence about buying one and now you made up my mind i will stick with the GP-38s as they seem not to have any issues. By the way what is a bypass wire and why doesnt Aristocraft install them? And what are Kool aiders?
Thank you.
Johnn
 

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Thanks Ted, that was a great article on fixing Aristo diesels. For the pitting of the wheels might I suggest that you start using Kerosene to clean your track. It is non toxic and leaves a thin protective film on the track after cleaning and aids electrical contact. I have used it to clean HO gauge track as well as gauge one. I learned this trick from an 'old timer' in the hobby. It is mostly a forgotten fix now days. Modern cleaners leave the track dry so that you get arcing between the wheel and rail which causes the pitting you see on your wheels.
 

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Discussion Starter #9
Johnn,

It's a shame that the Aristo GP40 has this poor quality wheel issue as the loco is a beautiful model.
As to the motors, Aristo has commendably stood by them and replaced them. So I think anyone buying one should be taken care of here.

That said, I believe the profound problem is the wheel quality for those of us that use track power. At the present time we don't really have any good options.


-Ted
 

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Ted

Great analysis of the issues with the GP40. Too bad as I was in the market and will wait awhile befor I make a purchase. With regard to the wheel plating it has been this way since I first purchased a FA1 back in the 90's with the Korean made locos. It seems that the plating makes no differance to the electrical pick-up but with the plating they tend to slip easier. I'm not sure what the metal compound the wheel is made of but I have hundreds of hours on the diesels and no dedgradation on electrical pick-up. I run 50 cars behind 2-3 of the old FAs and they are still runnen. I use a light oil on the track (Rail Zip)to keep thins moving and I have 1.5% grades with minimal slipping.

I wouldn't worry about the plating.

I wish they would just get rid of the plating altogether.

Howard
 

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Johnn: Nick was privy to some of the early results of this investigation, which I gave to him under the agreement that he did not divulge everything until Ted was finished. So Nick's decision was influenced by what you see here.

John and Jerry: clean track is great, but I do not believe that this would reduce or eliminate pitting, or loss of plating. This premature failure seems to be related to the quality of the plating.

Howard: Plating does make a difference on electrical pickup in this case because the base metal is steel, which has even more sparking! Also, this allows rust in at least my humid environment, and that most definitely affects electrical-pickup.

Regards, Greg
 

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I wonder if this is related to the problem George Schreyer described, with his USAT loco--very high current draw equals excessive wheel pitting?Haven't there been problems with high current draw with these?


Aside from that I agree, better plating/wheel material would be good
 

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Very well could be, the GP40 motors are unique to just this loco, and it is the first time Aristo used them.

I sure wish that the base metal for the wheels was brass, but, no malice intended, steel is the cheapest thing here, and that is the bottom line.

Regards, Greg
 

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Just to add my 2 cents worth, I've had plating problems on engine wheels made by several different manufacturers, it is not just an AristoCraft problem. The plating has worn off on several LGB, Bachmann, and USA Trains locomotives.


So far I haven't detected any wear on my Accucraft locomotives, they may or may not be plated, I don't know.


The wearing of the plating is a fact of life. If you run an engine a lot, you will wear through the plating. If the engine draws a lot of power there will be sparking and more pitting. I really noticed this on the original LGB Mallet (2085). It is also a problem with the Sumpter Valley Mallet. It seems to be more of a problem with two motored engines with smoke. The only single motor LGB engine that has this problem is the original Zillertal steam locomotive (2071).


Chuck
 

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As always Ted excellent write up. I will be taking a look at the truck wiring going through the frame to make sure no bare spots are showing up. Later RJD
 

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Nice review Ted!
I will be selling off my Aristo loco's because they are only suitable for battery power.
My thoughts are dont' waste your time and money converting these to DCC or DCC sound.
 

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This is way overstated. Aristo locos have issues, but I have three running very well on DCC--an RS-3, a Pacific, and a mikado converted to a consolidation. They are not perfect, but nothing is. They run fine with some tweaking. The RS-3 has run fine for me out of the box, using the PnP socket to install a QSI card. The socket is still in the Pacific, but was pulled out of the Mikado.
 

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Lownote, now I'm a little confused. Awhile back it seamed like the DCC guys were pushing the QSI for sound and DCC control of Aristo loco's. Seamed like it would be an easy install. I have nothing against DCC, I have some DCS loco's and like the concept. I would think that loco's without plug N play would be more difficult due to all the wiring I would have to perform..............Jim
 
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