Coincidence or correlation?

[WGL]

 Recently, the F7A unit of my Intermountain F7A-B DCC with sound consist began losing electrical contact.  I cleaned the underside of lint & fuzz, but that didn't seem to help.

Meanwhile, last night, I tired of my Bachmann 4-8-4 continually derailing at the same turnout.  I'd twice added weight to the front truck.  Sometimes, it would run a dozen laps before derailing, but lately, it has derailed after 1 or 2.  So, I retired it to the train yard.

I had both trains on the same oval of track.  The F7A-B never derails on the turnout.  Without the 4-8-4, the F7A resumed normal running.  I tried it again tonight, & it ran fine.  With 5 amps of power, it can't be that I had too many trains running.  Is there a possible connection between the presence or absence of the 4-8-4 & the F7A's operation?

[rustyrails]

With regard to the 4-8-4 derailing problem:  Check the gauge of the pilot truck wheels.  Run the loco slowly through the turnout repeatedly until you can see what is happening.  A flashlight may help.  You shouldn't have to weigh that leading truck down.  By doing so, you can upset the balance of the engine, possibly affecting pick-up and/or pulling power.
Rusty

[Jim Banner]

Recently, the F7A unit ... began losing electrical contact.

Without the 4-8-4, the F7A resumed normal running.  ...  Is there a possible connection between the presence or absence of the 4-8-4 & the F7A's operation?

Running or not running your 4-8-4 could not cause or prevent your F7A from making or losing electrical contact.  But it very definitely could cause the same symptoms as loss of contact.  If the 4-8-4 is intermittently shorting the track, then both it and the F7A could be intermittently losing electrical power.  But not through loss of contact.

With short duration short circuits, your command station may not have a chance to react and the locomotive causing the shorts may show nothing out of the ordinary except a flicker in its headlight.  Meanwhile another locomotive may show jerkiness or hesitation with the brief losses of power, either because it has no flywheels or because it is reacting to the loss of DCC signal.  Normally a decoder has to receive a valid data packet every 20 seconds or so, otherwise it is supposed to stop.  This is controlled in CV11.  So if the F7A is missing some key data packets, it could be shutting down.  This might be exacerbated by the value in CV11.

Then again, some decoders seem very anxious to switch to dc operation if they do not see a DCC signal, valid or not.  I cannot tell you that one or the other of these IS happening, only that it IS POSSIBLE for one locomotive to adversely affect another.

Jim 

[WGL]

 Thanks, Rusty.  I followed advice by some on this forum to add weight to the leading trucks.

Thanks, Jim, for explaining the feasibility of a correlation between the activity of my 4-8-4 affecting my F7A.  Why the A unit is affected but seemingly not the B unit, both DCC with sound, is another piece of the puzzle.

[mf5117]

I had that problem with my 4-8-4 . I found that one of my Bachmann EZ Track #5 switches , was twisted . right when it would get to the frog , de-rail and short . I checked the wheel gauge weighted the front trucks  like was suggested . but to my avail , I had 2 switches that were twisted and humped . the ties were coming loose from the grey road bed , I replaced them . Now she runs well around the layout . I only run the 4-8-4 on the 22" rad . I still think the engineer has to wear a neck brace from whip-lash . Mine also wobbles a little , I believe it was Rustyrails said " you might check the drive wheels " . I found the 2nd set from the front were off . It was like they were bent , never took one apart , but I did  yesterday . really seemed to help . I thought you had to have big kahoneys to tear into one .mine are bout as big as bird seeds . I got it back together .  I wish i had a bigger rad than 22" .but oh well someday    peace to all .

[WGL]

mf5117, thanks for your contribution.  My widest curves are also 22", & I run my 4-8-4 on them.  How did you adust the drive wheels?

[mf5117]

It was quit a task . Sorry I haven't got back . I used an nmra gauge I bought at our LCH . You should have a diagram , that came with your 4-8-4 .
I began with removing the the 2 floating trucks, for clearance .You will see 3 screws remove them . Then the black cover plate will come off . If your not sure I wouldn't attempt it . There will be another plate with the brass contact that go to the driver wheels . You must take extream care when removing this part from the driver wheels . It is connected by the rear floating truck .Where it screws in . you will see the 4 sets of driver wheels .The second to the last has the plastic gear .I did not remove the linkage from the driver wheels .But they will come up from there seats . The 2nd set from the front  was not seated to the axle . I checked all of them per the gauge . and reversed the process . ...

If your not careful .You can ruin your loco . I got lucky when i put it back together . 6 hrs I spent on her .
good luck  peace to all

[WGL]

mf5117, thanks for the details.  I shall heed your warning.  I once took my spinning reel apart to repair it, but it never quite recovered from the operation.   

[boomertom]

WGL,

I've had that problem also, especially with spin cast reels, one reason trains have taken more importance than fishing.

Tom

[rustyrails]

A good backlash on a bait casting reel can keep you busy all winter.  LOL
Rusty

[mf5117]

Especially if you get a nice Walleye , from 40 ft deep !!!!!