A.F. #303 Engine Stopping over 90 Degree Crossovers only

[Dr. Robison]

Hey all! This is my first post on here.

I'm fixing up my grandfather's S-Gauge A.F. track/cars/engines,ect.  Running an 8B transformer that puts out a max of 16 volts (not as much as I'd like but what can I do).  Cleaned all the track up nice and shiney and replaced some pins with new ones (they make good contact don't worry).

I measured with a muilti-meter and from what it tells me anyway, every piece of track over the whole layout is getting the same voltage..aka no voltage loss...supposedly.

My problem is: The engine is fine over turnouts..it's just when it goes over 90 degree crossovers the engine stops on the other side. Now if I go over FULL SPEED, its momentum will carry it over, but I don't always want to do that! The engine sounds like it's still getting power because the tender is humming, and when I cycle through neutral, to reverse, to neutral, to forward again, it'll go again.. It's JUST when it losses power to the wheels of the tender for that SPLIT second over the 90 degree crossover does it do something that the tender/engine doesn't like at all.

I've cleaned the wheels on the tender and on the engine..including the black plastic ones..with Goo Be Gone and I cleaned the copper pieces under the tender and there is no rust on those parts and they make good contact with the axles of the tender. I cleaned the track and all that just to eliminate more possibilities and that didn't work either..  It just seems to FREAK out when the front wheels on the tender go over the center plastic part of the crossover and are "seperated" for a second from the rear wheels of the tender.  

Anyway, thanks in advance for any help.

--Steve Robison    Saline, MI--

[stebbycentral]

#1) 16 volts is the correct value for a transformer of that vintage. 

#2)  On an AF locomotive, similar to HO scale trains, each wheelset of the tender constitutes one side of the electrical circuit.  If one set of wheels is completely out of contact with the metal track, you have no power.   It sounds to me like this split-second loss of electrical power is causing your reverse unit to cycle into neutral.  Ordinarily reverse units shouldn't be that sensitive.  What happens if you disengage the reverse mechanism using the lever on the bottom?  I would assume the locomotive would power right through.

 

 

 

[Major]

What stebbycentral said is accurate. The locomotive tender is not making contact continously through the crossing.  I think that is one reason why A.C.Gilbert removed the crossing on their large display layout.

What I would do to improve operation first is insure that all the tender pickup wheels are clean.  Second clean the bronze wipers and the axles and ensure that the wipers are making contact on both axles.  You may have to remove the wheels to do this to bend them down slightly so they have more pressure on the axles.  You may have only one wheel actually providing power.  Third check the bronze wiper and insure that it is tight. A loose fitting wiper could loose electrical contact when the truck bounces through gaps in the crossing.

One other option is to lock the reverse unit in forward so even if there is a momentary loss of power the locomotive will continue to move.

[lionelsoni]

There is a way to slow down the reversing unit's response:  Put a small bridge rectifier (http://www.radioshack.com/product/index.jsp?productId=2062581&filterName=Type&filterValue=Rectifiers) just upstream of the coil.  If that's not enough, add capacitance in parallel with the coil.

I think it's clear that the problem is with the crossing (not "crossover").  But measuring around a layout with a voltmeter would not have revealed a voltage-drop problem anyway, since the current drawn by such a meter is tiny compared to the current that a train draws and would not have created any significant drop even in rather high-resistance track joints.

[AF53]

Steve - Sounds like you've gotten real good advice, and BTY to the forum. It's great that you have your grandfathers train and are working on it, nice to be able to keep it in the family and handing it down. Thats part of the marvel of these "toys".

Please keep us informed as to your progress and post som pics or video if you can.

Good luck,

Ray

[Dr. Robison]

Whaaaaaat's shakin',

           Gonna be short because t's bed time BUT, I checked the wheels: clean. I checked the copper wipers: clean and have tension. I checked the axles: clean. 

I took the shell off the tender and watched several times as it went over the middle of the crossing and YES, yall were right, it was cycling SUPER fast down to neutral...then it sits there and hums and buzzes and waits for further instructions. 

Locking it into place DID make it power all the way through and keep going though it would hiccup a LITTLE bit, but at least it kept going.  I AM going to try the bridge rectifier though because I would like it to be able to back into my A.F. Stockyard with its car. I'll have to read up on how to attach it as I see the bridge rectifier has 4 prongs.

Oh also amazingly for some reason, before I locked it, the #303 would only really want to pull about 5 cars maximum, and after I locked it I got it to pull about 14 so not bad I guess.  Also now I have a reason to buy more rolling stock.

THANKS AGAIN for all the help. I really want to nail down the basics of S gauge and its relative simplicity before I tackle O gauge big stuff and TMCC and DCC and Cab-2...whatever that means. :)

 

[Major]

In a obtuse way you can be thankful that your reverse unit works as well as it does.  Most of us have to "tender tap" to have the reverse unit drop down so it can cycle and that can be a problem when the locomotive is out of arms reach! 

Welcome to the forum.  You will find a rich and diverse knowledge base here and all are very helpful.