I installed a second pickup shoe on my E40 (39140) to improve its running over dirty track. Here are the three steps I took to do this:

1) Tap threads into existing hole in bogie.

2) Fabricate a pickup shoe contact plate for bogie frame.

3) Run additional red wire to PCB.


First of all, some threads need to be created for the pickup shoe fastener. I used the same thread size as the existing pickup shoe uses, which is a 2mm thread: M2 x 0.4. You will need both a starting tap, as well as a bottoming tap to create threads the entire depth of the hole. Also, a racheting tap handle is a big help, because you won't have to loosen your grip on the handle while tapping. Although the "right" way to put these threads into the bogie would be to remove the bogie from the locomotive frame and put it in a vise, I took a shortcut, and did it with the bogie in place. I didn't want to remove the PCB and disconnect the drive shaft, potentially creating other problems... .

To to cut the threads with the bogie in place means you will somehow have to ensure that none of the metal chips created drop into the gearbox. At first I was just going to tape off the gearbox, but I found the tape didn't stick everywhere. Even a small crack in the tape is enough for a small sliver of metal to fall into the gearbox.



Instead, I used a product sold in toy stores here in the USA called "Silly Putty". It is very soft and pliable, but is easily removed from metal surfaces. It seems to have a silicone grease-like feel, but doesn't leave a residue.








I gently pressed the putty over the opening of the gearbox, making sure all openings were covered, and then proceeded to tap the threads.






Once the threads were finished and the hole thoroughly cleaned of metal chips, and the threads tested with a fastener, I carefully peeled away the putty. I had no problem removing the putty, or any residual putty left on the gears, but I recommend you carefully check before moving on.






The next step is to fabricate a contact plate for the pickup shoe. I was lazy, and just used a piece of strip brass stock about the same size as the slots on the bogie frame. This is not as wide as the contact plate that Märklin supplies, but it is sufficient when using a long pickup shoe (which is the shoe the locomotive is supplied with). I can always go back and sculpt a piece of brass stock to fit precisely in the square recess, or order the exact part from Märklin.

You want to make sure the contact plate fits perfectly through the slots in the plastic bogie frame before soldering on the red wire. And, obviously, you want to solder on the wire before you slip the contact plate through the bogie frame; you don't want to melt the bogie frame!

After you've bent the contact plate tabs over the bogie frame, check to make sure the wire and soldered joint doesn't create a short circuit by touching the metal bogie. I didn't have a problem with this, and the cavity in the bogie seems large enough, but double-check anyways.






Next is running the red wire through the existing hole in the bogie and up to the PCB. Because the plastic bogie frames will be essentially tethered to the PCB, I left a generous length. The extra length will let you pull the plastic bogie frame fully away from the bogie when you want to lubricate and clean the gears. The green shrink tubing you see is just used to bundle the extra cable.

To hook up the new red wire you now have a choice: You can splice into the red wire serving the front bogie, and not have to touch the PCB with your soldering iron. Or, you can unsolder the front bogie wire from the PCB, and solder it your new wire from the rear bogie. Then, add an additional length of wire to the PCB. This is the choice I made. It gives me a little more wire to the front bogie - I found the existing length to be a little short for my taste.



I have found a second pickup shoe to be a big improvement in running characteristics. Especially for slow-speed running; my locomotive has not stalled since.

A final bit of advice: If you do not have any experience tapping (threading) holes, I would advise against doing this. A 2mm thread is very small, and it is easy to cross-thread the hole, or break the tap itself, if you don't know what you're doing. I would otherwise recommend you remove the bogie from the locomotive and take it to an experienced professional. A third option would be to order a replacement threaded bogie from Märklin.

Marty,

I'm not completely convinced what you are trying to do ?

When you talk about dirty tracks, it is usually refered to as the outer tracks.
When you talk about the midlle contact, it does'nt get dirty but could oxidise and a nailfail or fine wet & dry sandpaper does the job.
In my years since I've been involved with Märklin locos I have never heard or exoperienced your saga regfarding this particular pickup shoe.
The BR 44 has 2 pickup shoes which are relatively shorter in lenght.

A bad contact is, as you've described it, from dirty tracks, inferior contact between bogy & chassy or lack of ground wire and with older locos dirty wheels.
To overcome these problems, a pickup shoe will do nothing to improve it.

to solve your problem, which is a new loco, have a look at the contact between bogy and chassy, have a look at the 2 axles of the bogy.
Get a multimeter and test the contacts and this will give you a 100 % proof what is going on regarding "bad contact".

It could be your brushes not being pushed in correctly or the tension spring is loose.
check all your wire contacts.

John

Edited by user 08 September 2010 12:10:22(UTC)  | Reason: Not specified

Hi John,
The Soft Drive Sine motor as implemented in the E10/E40 has very little inertia. It is a small motor turning two driveshafts with worm gears. At slow speeds it seems the slightest interruption to the current will cause the locomotive to stutter or stop altogether. After cleaning my rails and the wheels of the locomotive, I would still notice the problem. I determined that it was the k-track pukos that must be slightly oxidized; I live within 1.5 miles of the ocean, so the climate here I'm sure is to blame. Also, I don't run my trains every day, so there is a lack of cleaning that the pickup shoes naturally provide. No other locomotive I have seems to be so sensitive to this, and I believe this is because all of the other loks I have will coast a bit if power is lost. I got into a routine of burnishing the pukos at every location the locomotive stuttered or stopped, but I got tired of that and installed a second pickup shoe instead. Problem solved.

Kimball,
I can understand your feelings completely; I'm not too thrilled modifying expensive locomotives either, but I want something that performs to my expectations. I sometimes feel that it is Märklin's job to do this, not mine, but that's the way it goes...

Marty - Nice pictures and interesting solution. Since you recommend against tapping a hole, another option may be to form threads with epoxy. It worked to add a pick up on a E44 I converted to three rail. -thanks.

Marty,

really interesting "fix", I like the silly putty touch. I'm guessing but you are still running a single transformer with analog correct? As Mike C mentions, for someone with multiple power districts and boosters having this double slider setup would not be a good idea I think.


Looking forward to your next project, you've done some interesting stuff.




r/Thomas

Sorry for the OT post.

Eric,

I use http://tinypic.com/ as this site automatically creates url's for inserting on the forum. You can also try www.smugmug.com which uses Amazons server network, Google's http://picasaweb.google.com/home also flickr at www.yahoo.com and others.


Back on topic, once you have that sorted please post the new thread.


Regards,


Thomas

Mike: You bring up some valid points that I should have mentioned; yes that could be a problem with multiple circuits, or upon entering a stop section. My layout doesn't have either configuration, so for me that's no problem. My problem seems to be oxidation of the pukos due to my proximity to the ocean. So adding a redundant pickup shoe for me makes sense, and it is within my skill set. I finished the task in an afternoon. Also, I haven't fundamentally changed anything about the locomotive or decoder. I can simply unscrew the second pickup shoe, and I'm back to the original setup. I thought about installing a capacitor, and talked with Eric about this, but I thought installing a second pickup shoe would be within my skills; whereas installing a capacitor and soldering multiple connections to the PCB may be more risky for me.

I don't want to give anyone the impression that my modification is right for everyone and all situations; I just wanted to share what I did.


Thomas: Yes, I'm just running a single analog circuit. My layout doesn't do alot, but what is does do, it does it well.

You are perfectly right, thank you.
I myself added a shoe to the tender of a br18.4 with locksound decoder, and alzheimer behavior vanished.
I must say that modification was quite easy (just some bakelit and glue).
I have also tested the addition of a memory cap to the ls decoder.
Both solutions work well.

fred

Two pickup shoe makes sure disturb,if you are using for an exemple Marklins brake module!

Thanks, John. Is this just a K-track problem, or does this affect m- and c-track as well? The K-track pukos are much wider than the m- or c-track's, and the pickup shoe would therefore exert slightly less pressure on the pukos because of the greater surface area. I seem to remember a thread awhile back about a rotating abrasive drum that was mounted to freight car, and could be pulled along to clean the pukos.