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Bachmann K7 - Fix for Locking up when reversing.

6K views 33 replies 16 participants last post by  David Fletcher 
#1 ·
At least two other people have reported this symptom.
The loco runs fine in one direction. Stop loco and reverse direction, SOMETIMES the loco locks up and raises the second driver. A couple reversals and the loco heals itself. Can happen either when going forward and reversing or going backward and reversing.

The following is just ONE cause of this symptom.

I sketched in hidden parts of the reverser in the picture of the right (engineers) side of  the K27.


Look close at your loco, Make sure the screw is not missing on the engineers side.

ALSO!
Look close at BOTH sides and make sure the blue part goes through the center of the green part. If not, remove the screw. Once both sides are properly engaged, install the screw.


B0B
 
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#3 ·
TOC,
Are you saying this can't cause the problem?
- or - 
Are you saying that you have found another likely cause.

I hear rumblings about loose counterweights, but, so far I have not had them cause any problem. 

But then I only have one Kay and only 3 hours to look at it. So Please enlighten us mortals.

B0B
 
#5 ·
After 10 or so hours of running without a problem, my K has developed a hitch in its git-a-along.  If it runs at all it sort of hops down the track.  More likely than not it won't move in either direction.  It appears that I have the same problem the Greg photographed in the previous post.  There seems to be a lot more play in the wheels and counterweights.  There is a modification over in the Bachmann forum that I'm going to try as soon as I can get some .007'' brass.

Chuck N
 
#8 ·
Posted By chuck n on 01/21/2008 5:30 PM
Thanks, TOC

Sometime I'm going to learn not to buy a Beta.  I should wait for the rerelease, but it is one beautiful engine.

Chuck


Chuck,
Everybody gets a beta./DesktopModules/NTForums/themes/mls/emoticons/crying.gif
 
#10 ·
Tony:

I think that there are more Betas from some manufacturers that others. 

I have three Bachmanns that I run regularly, a climax, connie and the new K-27.  Only the climax has not had a significant problem.  After the Connie stopped, I used TOC's suggestions for the Connie gears, and I am in the process of trying to fix the K-27.  I also had trucks on the Connie tender break.  No replacement trucks were available from Bachmann.  I now have Accucraft trucks on the tender.  I also have LGB, USAT, Accucraft and Aristrocraft engines.  Of 30 plus LGBs I have had to return two, one for a failed sound unit, and one for design flaws in the motor block (the original red and green mogul).  Both of these were repaired and returned.  After many years of heavy use I've had to replace gears and motors in a couple other moguls.  LGB always had parts and getting them from LGB or the LHS was never a problem.  The only other engine I had to send back was the Aristocraft Mikado with a broken axle.  Aristo returned the engine in a timely fashion and I haven't had any further problems.  Unfortunately, Bachmann seems to lack a supply of parts and we are  the Beta  testers.   

Cheers,

Chuck N

PS I've been running my Accucraft K-27 for a number of  years without any significant problems.
 
#11 ·
Thanks to help from this thread and one over at Bachmann "Loose counterweights on K-27".   I now have my K back on the tracks and running.  I put in 0.008" shims as suggested by TOC.  If it weren't for all you helpful guys, I'd be getting more upset by the minute.  Thanks to Tommygunner who started the thead at Bachmann and Bob who started it here.  Special thanks go to Bill375 at Bachmann who suggested that shims were needed and TOC here who suggested going a little thicker on the shim.

I seriously doubt that I would have figured it out by myself.

One other thing.  Using the lid to the engine box to hold the upside down engine works great.  I'll have to try it with some of my other engines.

All's well that ends well, at least until the next problem.

Chuck N
 
#12 ·
Reading the above I'm glad I did not buy one of the first run Bachmann K27 - learnt my lesson with the Bachmann Three-Truck Shay (dcc sound version) which shut down when the voltage exceeds 22volts - and I run MTS/Massoth at 24volts.

Given that, I'm very happy with my Bachmann Two-Truck Shay and Heisler (both dcc'd and fitted with Phoenix Sound) - they sound just great winding their way up the garden!!)

Keith
 
#14 ·
Blackburn, if you don't have a use for that K-27 send it my way. I'll put it to work!!
 
#16 ·
I didn't.
Looked all over. Everyone was out

Got back home at 10:00 PM worn out from the driving.

Sat down, stared at the poor dead Kay and sipped on a can of Coke.

Then it hit me.

Couple hours later,  Kay is alive an rolling.

Coke cans are .004
Fold and then cut.
 
 
#21 ·
You will go blind trying to fit two thicknesses of shim into that gap.

I bought $41 worth of brass shimstock, in various sizes.
I have found on several that #3 axle takes about a .006" shim, but careful smoothing of the VERY rough machining of the axle flat with a file makes .008" work.
 
#22 ·
You will go blind trying to fit two thicknesses of shim into that gap.


 


Yep, nearly did go blind on the first few till I worked out a method.


Not saying aluminum is the way to go. Wait and see how this holds up, I may have to do it over with brass, but at least it got me going.


What I did:
Cut out a BIG piece of the coke can. Fold it in half so  the red is on the outside Makes it easier to see.) Starting at the fold, make cuts with scissors at 90 degrees from fold. Cut strips the exact width of the flats on the shaft. (well, as close as you can.)


Each strip is a couple inches long and contains two thickness of can with a fold on one end to hold the strips together.


I inserted a strip, fold end first into the counterweight. Push the strip through the counterweight until a tiny bit of the red paint appears sticking out the back side of the counterweight. Positioned the counterweight on the end of the shaft and slide the counterweight until the shim is captured between the inside flat of the counterweight and the flat on the shaft. wiggle the counterweight  by tilting it back and forth while applying light pressure to push the counterweight onto the shaft. It  takes a bit of work. Helps if you hold the other counterweight and not be pushing against the loco side-frames or journals. Work it on slowly with firm pressure.


Once the counterweight is pretty much seated, use an x-acto knife to trim the two layers of the aluminum flush with the bottom of the outer hole. Install the washes and screw. Tighten firmly.

Disclaimer:
I am a novice. It seems to be working for me, but if at all possible follow TOC's advice. I used this method because I do not have ready access to brass shim stock. I will probably replace these shims with brass as soon as I can locate the proper materials. Use my method at your own risk. You can not go wrong by following TOC's instructions. So, you might be better off waiting until you find the brass shim stock or even waiting for Bachmann to provide replacement parts. (I wouldn't hold my breath).

B0B
 


 
 
#26 ·
I don't think the vast majority of K-27 owners are going to want to fix this themselves. And though some are in denial, the problem will have to be fixed sooner rather than later.  I think that better fitting, replacement counterweights are by far the best solution.

John
 
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