Problem with FT-A/B consist

[wazmau]

Hi,

I have Bachmann FT-A and FT-B units and have run into a strange problem. I am still in the process of building my layout so to test run I used my son's layout. (The B unit was a present from my kids so only a recent arrival.) My son't layout has a fairly steep rise round a 22" curve. Normally I never have problems but while pulling 4 passenger cars, the B unit seemed to just jam at about 90% of the way up. I gave it a little push and it got going again till it got to about the same point on its way round again and the same thing happened.

I used just the B unit to pull the cars and it had no problems. Put the A unit back and got the lockup. I reversed them and had the B unit in front and this time the A unit locked!

Does anyone have any ideas why the 2nd unit in line seems to lock the drive when being pulled up a hill? Is there a grease I could use on the drive train that may help maybe?


Thanks


Warren

[Joe Satnik]

Dear Waz,

Sounds to me like the "vertical curve" at the top of your hill is too abrupt. 

I'm guessing that the first unit is lifting the second unit's wheels off the tracks. 

I suppose one way to test that theory would be to uncouple the two engines and temporarily "tow strap" them together.  (Bread tie?) 

If this corrects the problem, you will need to make a more gentle transition from slope to flat at the top of the hill. 

Do you still have lights when the lockup occurs?

Hope this helps.

Sincerely,

Joe Satnik 

[wazmau]

Hi,

All of the wheel are on the track and I can remove the front unit and then I have to rock the locked up one to get it to free up the wheels. When I tried with the units reversed (b-a) the light did stay on so I am sure it is a jam of some sort in the drive mechanism.

Warren

[rowdyjoe]

Wazmau,
  I run an A&B pair also but, have never had the problem you describe.  I run two identical decoders made by Digitrax and the only problem I've had was the B unit reprograming itself in various CVs occassionally (caused by OPS mode programming other locos I think).
   EXCEPT ... when I first got the decoders installed I programmed the A unit with it's road number and the B unit with the same road number plus 1 (eg.  A = 1500 and B = 1501).  I consisted them but, ran into "odd" behavior.  I reprogrammed both deocoders to the same road number (eg.  A&B = 1500) and the odd behavior stopped.  I can't explain it but, I haven't had a problem since except the above mentioned occassional self reprograming.   
  So, you might try programming them both to the same road number.  It works for me but, I'm a rookie at this game.

Good Luck,
RJ

[RAM]

RJ Do you have a programing track?  I use a yard track with dpdt switch.  One way for running, the other way for programing.

[wazmau]

Looks like I have a work round. Someone suggested I try running the B unit backwards and see if that helped and it works perfectly. There must be something in the drive of the B unit that doesn't like being pulled in the forward direction. The pull comes from the A unit when the load is greatest on the incline. Didn't fix it but so far has solved the problem. 

[nyoun]

I did not see in your original question any mention of DCC so I will not go there.  In trouble shooting I have learned that when a problem occurs at one place with one unit, car or engine it is a condition of compound problems.  If there is a switch or a crossing at the point of problem I would look to a low coupler trip pin.  If it is not a switch or crossing I would look for a track nail that has backed out above rail height, or a bad rail joint at the point of stopping, though this is far less likely.  Loading of an engine can cause the chassis to "motorboat" which is to say raise in front and squat to the rear.  Combining two units can have one pushing or pulling the other.  The Bachman truck suspension is very supple to allow the units to traverse really bad track, well.  It is a function of their trainset history.  However, the downside is that the high truck pivot point can exaserbate the "motorboating" problem with vertical curves, lack of curve easements, track irregularities caused by temp or humidity changes, or pulling steep grades or heavy loads.  It can cause one coupler to rise up on another, thus driving the coupler trip pin even further too low.
Of course, when you reverse the unit the offending trip pin curves in the other direction and rides right over what had been an obstruction.  So my advise is to check the coupler afixing clip to be sure it is holding the coupler in the correct alignment.  Then check to see if the coupler has too much vertical play.  Any is too much but excessive amounts cause real problems.  And then bend the coupler trip pins up just a little bit more than the manufacturers reccommend.  (use the Kadee special trip pin pliers if you have them or have a friend who does)  The precise location of the trip pin is only important if you are using magnetic uncouplers.  And so few of us do any more.  So I always make sure they have a little excessive curve to make the trip pin clearance greater, as a preventative measure.  Its simpler than improving my trackwork.

[wazmau]

Hi,

I do use a Powercab for DCC. The track is ez-track which is glued down so there are no track pins just a curve and a slope. 

The problem occurs at a point where all cars are on the curving slope, that is where the load hits the max. When the 2nd unit stops, the wheels are jamed and need to be rocked to release them so it is definitely a mechanism problem which may be a product of the removing and replacing of the motor during the decoder fitting. ie: the motor may not be in the exact same place which could be causing jamming.

At least that is the conclusion I have come too. When I get time I will try to investigate further so I understand the drive mechanism better. In the mean time I will just run it backwards  .

Warren