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Author Topic: 10 wheeler won't run forward direction  (Read 2591 times)
amflyer1

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« on: June 01, 2011, 01:38:39 AM »

I have a hardly used 10 wheeler that runs like a champ in reverse but will not run in the forward direction. The motor just hums and the drivers creep. Two different transformers yield the same results. There does not appear to be any binding in the drivetrain. Any ideas on how to fix the problem would be welcomed.    Huh?

Thanks,
Rich
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Loco Bill Canelos

Model railroading since 1947


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« Reply #1 on: June 01, 2011, 08:05:16 AM »

Rich,
From what you say it may be an electrical pickup problem at least in part.  Try using electrically conductive grease at all points which are part of the electrical pickup .  Use a spray electrical contact cleaner first.   There is a polarity change switch behind the boiler front try switching that back and forth several times to clean the contacts.  Check the electrical contacts to the front truck and clean it too.

I am assuming the track is very clean if not clean it as well. 

Let us know how it works out or if there is a change in symptoms.

Hopefully some of the guys will have additional ideas. 

Bill
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Loco Bill,  Roundhouse Foreman
Colorado & Kansas Railway Missouri Western Railway
Semi Official Historian; Bachmann Large Scale
There are no dumb or stupid questions, just questions!
Joe Satnik


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« Reply #2 on: June 01, 2011, 12:05:00 PM »

Just curious as to what version chassis you have.

http://www.bachmanntrains.com/home-usa/board/index.php/topic,17178.0.html

Cradle your loco upside down (careful not to bust off the decorative whistle) and touch power pack leads to each of the pick up wheels, one axle at a time.  (One lead to the left wheel, one lead to the right wheel of an axle.)  Switch the leads to the opposite wheel (reverse power).  Any change in symptoms/action from when it was on the track?

Four axles should pick up (2 front pony truck axles, plus front and rear driver axles.)  

Arrow on pony truck should point forward.  

I don't think the blind drivers (wheels with no flanges) pick up.

Make sure that the polarity is the same for all 4 axles.  In other words + power pack lead to left wheel, and - power pack lead to right wheel should cause the driver wheels to spin in the same direction, no matter which pickup axle wheels are being touched with the leads.    

Let us know.

Sincerely,

Joe Satnik

edit: grammar
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If your loco is too heavy to lift, you'd better be able to ride in, on or behind it.
amflyer1

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« Reply #3 on: June 01, 2011, 02:04:36 PM »

I admit, this is a strange one.

I have performed bench testing with leads connected to pilot trucks, arrow forward. No improvement.
Touched leads to all four drivers. No improvement.
Removed bottom cover and attached leads to motor plugs. No improvement.

Motor in the forward rotation will not turn the worm gear enough to move the armature shaft from one end of the motor to the other.

I think I have revision 5 drive. Gear bulge is offset.
I remain puzzled.

Thanks,
Rich
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Joe Satnik


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« Reply #4 on: June 01, 2011, 04:30:01 PM »

Dear AF1,

How much end-play in the motor shaft /worm gear ? 

Is it possible that the motor shaft has so much end-play that the commutator moves out from under the brushes in the forward direction rotation ?

What happens if you force the worm/motor shaft  to operate in the same position while in forward that it was in reverse? 

Sincerely,

Joe Satnik 

   
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If your loco is too heavy to lift, you'd better be able to ride in, on or behind it.
amflyer1

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« Reply #5 on: June 02, 2011, 01:37:32 PM »

I have found the problem and it is quite an embarrassment. I have installed 2 wirewound resistors to lower the voltage going to the motor to make the MTH smoke unit I installed smoke adequately. These are located just in front of the weight. Additionally, I mounted a 15 volt voltage regulator to the weight to use it as a heat sink. This made the weight electrically active with a negative charge. Apparently the weight would shift slightly and touch the resistor wire. It only came into play with the DC polarity was right. In this case the forward running condition. Grinding the weight slightly corrected the problem.

Thanks for all your attempts to help.

Rich
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on30gn15


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« Reply #6 on: June 05, 2011, 08:55:16 PM »

I have installed 2 wirewound resistors to lower the voltage going to the motor to make the MTH smoke unit I installed smoke adequately. These are located just in front of the weight. Additionally, I mounted a 15 volt voltage regulator to the weight to use it as a heat sink. This made the weight electrically active with a negative charge.

Ya know, without having that information to start with, was there any way on God's green earth we would have, could have, made any headway figuring this out?
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When all esle fials, go run trains
Screw the Rivets, I'm building for Atmosphere!
later, Forrest
NarrowMinded


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« Reply #7 on: June 05, 2011, 10:15:35 PM »

I second that, On30gn15... since my Crystal Ball broke that one would be a tough one Tongue

NM
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