622 NW-2 Losing Power

[IDM1991]

I have a Lionel 622 NW-2 switching locomotive that I run rather frequently.  Of late, it has completely shut down upon throwing it into reverse via a KW transformer, and occasionally, it will will shut down after only a few laps.  On other occasions, it will run fine.  It usually pulls a train of about five or six loaded (but otherwise lightweight) postwar freight cars.

Now, it should be noted that my layout consists of an independent outer loop of tubular track, and an inner loop of tubular track that includes two stub-ended spur tracks and a passing siding.  The turnouts are all of the 042 manual variety.  I first encountered this problem after attempting (rather foolishly, in retrospect) to double-head the NW-2 with a 2343 F3 on the inner track.  The former has not been behaving since.  The old cab unit runs fine, and a track-cleaning and bus-wire installation is planned.

The KW, I should point out, was repaired by a retired electrician at a train show in April of this year.  Would there be something amiss with the "B" throttle, which I use to control the inner track?  I don't believe the locomotive is the issue, because it will run fine on the outer track, and I don't think that a defective e-unit will simply shut down the whole machine, either.  Moreover, the red light on the KW does not go on when the 622 grinds to a halt after even a few successful laps around the layout, so a short-circuit may not be the issue.

Any suggestions as to how this problem may be fixed?  We are going to a train show next weekend and the aforementioned retired electrician will also be there with his group's Lionel layout and has said to bring down my problem locomotive. 

[ADCX Rob]

How does the 2343 run on the "B" side of the KW?

[IDM1991]

It runs fine on either track. What's puzzling about it all, though, is that the "B" throttle will run the inner track rather well one day, but not the next. One might have to wait a day or two before resuming operations. Sometimes the locomotive on the inner track will just shut down entirely with no obvious reason for doing so. Here's what I can determine thus far: a) this problem usually occurs after the reverse unit has been engaged, although this is not always the case; and b) I only began to notice this problem after I tried to double-head the two locomotives on the inner track, which is, as I say, completely independent from the outer loop. I did remove a rusting 0-31 curve from this inner loop, and while I have stored two small illuminated passenger cars on the passing siding, it seems a bit of a stretch to connect them with a faulty locomotive and/or transformer.

[Plate Rail]

If the lighted switches dim and brighten with the throttle on your transformer you can pretty much eliminate the KW as the problem.  You'll find having a cheap multimeter handy for troubleshooting.

Time to take the shells off your engines and check for loose wiring that could cause intermittent shorts or continuity issues.

Last but not least, check for worn out motor brushes. 

Bruce

[Hap]

Seem to remember reading in CTT about worn thrust bearings on the motor armature that only cause a problem during reverse operation, causing binding or interference on the gears or in the bearings as the thrust axis offsets slightly with the bearing wear.

A close look at the motor with the shell off may reveal more if the shaft rises or binds up when going into reverse.

[IDM1991]

Whenever this problem occurs, nothing will turn on.  The locomotive is quiet (no lights, no movement); the switch lights do not illuminate; and an illuminated Marx switch tower connected to the track fails to glow, even with the "B" throttle turned to its highest voltage output, as labelled on the transformer casing.  The transformer hums, of course, and nothing seems to be overheated therein.

Again, I might go down to the basement tomorrow night or two days from now, and have no problem.  Indeed, the locomotive sometimes buzzes to life and sits on the track in neutral before either shutting down or shooting forward (or reverse). 

[TrainLarry]

Take the cover off the transformer and check the 'B' and 'U' terminal posts inside on the terminal plate assembly. You may find that they are loose, and breaking the connection to the track. Replacement posts are available that bolt in, so you do not have to rivet them in like the originals. It sounds like the doubleheaded locomotives draw enough current to overheat the bad connections and cause them to open the circuit.

Another possibility may be an intermittent reverse switch for the 'B' throttle. If the terminal posts check OK, operate the reverse switch a number of times to see if power returns.

Larry

[IDM1991]

Today, I took the KW down to a train show and had one of the aforementioned retired electrician at the O Gauge exhibit look at it. He tested the 'B' and 'U' terminal posts on the exterior of the transformer and found nothing wrong with them. He did suggest, however, that there may have been something wrong with my track. Late this afternoon, I tried a few things he recommended in the way of detecting faulty track, including: a) pushing an illuminated van (caboose) along the track to see if any current was getting through at all; b) using a test light to detect the same (I used a rotary beacon connected to the centre and outer rails via alligator clips); and c) running my palm along the track to detect heat. I tried all three methods to no avail. I did, however, try pressing the direction button on the 'B' side of the KW throttle several times in rapid succession. This succeeded in restoring power, but I'm concerned about how - if this is indeed the underlying issue - to go about repairing this. Is it simply a case of tightening something inside the transformer? We plan to go back to the show tomorrow, and I'll ask if this is a possibility.

[TrainLarry]

The direction switch is definitely your problem. Take off the cover and look underneath the bearing plate assembly, and you will see the contacts of the direction switch that are opened when you press the direction button. You may need to clean and burnish the contacts a bit to get off any dirt or oxidation. Check to make sure the contacts are completely closed and making good contact afterwards.

Larry