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babuff
Little Six
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 Posted - March 26 2014 : 08:52:35 AM
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I recently got a Bachman F-7 unit that was not running. I striped it down and the motor was OK. The problem came down to the wheels and the wipers not making contact
I need some ideas on making a better contact wiper. There have been posts here on the forum regarding this problem, but I can't locate them. Can anyone help jog this old man's memory or tell me how you may have fixed the problem yourself?
leo
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Posted - March 26 2014 : 09:20:13 AM
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Hi Leo, I have always thought that that style of Bachmann loco ran pretty well. All I do when I get one like that is to take a polishing wheel in my Dremel tool and buff the large contact plates where the wipers on top of the trucks rub. I also polish the backs of the wheels and the actual brass wheel wipers, as well as the wipers on the top of the truck.
That has always done a good job for me. I have frequently found that a major culprit in causing troubles is that right at the point where the wiper touches the wheel, you will get a buildup of dust and crud. This just kills the engine. Sometimes just slipping a knifeblade into that connection will dislodge the "stuff" and restore operation.
I have no scientific proof but I still think that a little Wahl hair clipper oil on these contact points helps prevent oxidation and make them run better. Of course any oil can pick up some dirt but I think in the long run it is worth the speck of oil.
Randy
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Posted - March 26 2014 : 11:21:10 AM
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quote:I still think that a little Wahl hair clipper oil on these contact points helps prevent oxidation and make them run better. Of course any oil can pick up some dirt but I think in the long run it is worth the speck of oil.
Originally posted by rbturner - March 26 2014 : 09:20:13 AM
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I've also heard of people using automatic transmission fluid (ATF) that way. Any such oil should be used sparingly to minimize the dirt attracted. I've found that periodic cleaning is still necessary because, over time, any arcing that happens in the contact can cook the ATF into goo.
Carpe Manana!
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Posted - March 26 2014 : 9:05:55 PM
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Hi All,
I see it has a metal base. Is this how all of thier new engines are made or is this an older one?
Thanks
Mytyco
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babuff
Little Six
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Posted - March 27 2014 : 1:00:38 PM
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this is a Hong Kong unit and is an all metal unit. not sure of the date.
leo
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Posted - March 27 2014 : 8:59:51 PM
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Leo, the pickup on those units is excellent. In your photos the wipers appear to be well sprung against the wheels. The only issue I can see is that one of the wipers that rubs the chassis contact plates is bent downward. If you make sure that they all stick up at an angle and make good contact, there shouldn't be a problem.
One problem these do have is that the front edge of the contact plate that runs under the fuel tank comes too far forward and tends to catch the gearing on the front truck. I grind a rounded recess into the front of the plate to make it clear the gears.
I remotored one with a Mabuchi can and added lots of weight, and it can go toe-to-toe with an Athearn super weight F7.
The Tyco Depot
Edited by - NickelPlate759 on March 27 2014 9:00:54 PM
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Posted - March 29 2014 : 11:31:55 AM
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I believe that's known as a Kader chassis, that Bachmann used. I have a few of those myself, they are heavy and run well when working correctly. Generally, no problems with the contact design, they usually are just in need of clean-up and get all the crap off the finger-tips, which clog up and cause the problem with continuity. Sometimes you have to pull the truck apart so you can bend the contacts in some to put more tension on the wheels, but other than that, they seem to work well when maintained. No additional contacts should be needed.
Jerry
" When life throws you bananas...it's easy to slip up"
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Posted - March 29 2014 : 3:54:09 PM
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I clean the contacts and the back of the wheels with fine emery cloth. I also add contacts to the rest of the wheels without contacts. I use either small screws or gel ACC to attach them to the trucks. I scavenge them from units that have gone to the big layout in the sky. In the old days I use to take them to work and gold plate them... until I got caught. Four more wheels picking up current makes a huge difference.
Vince
We are born naked, wet and hungry. Then things get worse.
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babuff
Little Six
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Posted - April 01 2014 : 10:36:46 AM
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Sorry for the delay guys. spring is coming (finally!!!) and have been busy prepping the garden.
I cleaned the contacts and wheel faces and I still don't get any continuity reading from wheel to pickup. It seems someone stuck something in there to bend the contcts and made it worse.
I vaguely remember a detailed post on using KD coupler springs and one for direct wiring.
leo
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