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Author Topic: K-27 locks up when changing direction.  (Read 2968 times)
tommygunner

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« on: January 17, 2008, 08:24:43 PM »

My DRGW 455 K runs sweet and quiet but it has this little anoying quirk after a few loops around my indoor layout I will stop the loco and try to reverse it,some times it reverses some times not.  When it does not reverse I noticed the  2nd axle lifts up and the siderod jambs. If I pull rod down loco runs ok.Siderod has a joint between 2nd and 3rd axle to allow the rod to flex as drivers negotiate rough track, however rr track is perfectly flat. This also will happen if loco is run a few laps in reverse then stopped and I try to run it forward . I'm starting to think that problem is related to prior post about loose counterweights. There is a lot of play in the siderod /counterweight part of the mechanism and I wonder if that is causing lock up problem as motor /gearbox runs smooth as glass. Anyone else having this problem???, Any help would be appreciated.
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glennk28

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« Reply #1 on: January 17, 2008, 09:24:07 PM »

The lockup soundl like a crank out of quarter--which could be the result of something loose. Time to check everything.  gj
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the Bach-man
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« Reply #2 on: January 17, 2008, 11:57:39 PM »

Dear All,
I am looking into the counterweight issue, and will report back.
Thanks!
the Bach-man
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Doug.Oaks

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« Reply #3 on: January 18, 2008, 10:21:41 AM »

My K does the same thing. I have to give it a bit of a small shake to get it to go forward after reverse. But what a beautiful engine!
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bobgrosh

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« Reply #4 on: January 19, 2008, 11:43:03 PM »

My DRGW 455 K runs sweet and quiet but it has this little anoying quirk after a few loops around my indoor layout I will stop the loco and try to reverse it,some times it reverses some times not.  When it does not reverse I noticed the  2nd axle lifts up and the siderod jambs. If I pull rod down loco runs ok.Siderod has a joint between 2nd and 3rd axle to allow the rod to flex as drivers negotiate rough track, however rr track is perfectly flat. This also will happen if loco is run a few laps in reverse then stopped and I try to run it forward . I'm starting to think that problem is related to prior post about loose counterweights. There is a lot of play in the siderod /counterweight part of the mechanism and I wonder if that is causing lock up problem as motor /gearbox runs smooth as glass. Anyone else having this problem???, Any help would be appreciated.

The exact same symptoms you discribe happened on mine.
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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tommygunner

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« Reply #5 on: January 20, 2008, 09:36:26 AM »

Bob,  Thanks for input but the valvegear is all assembled correctly and runs smooth.
On my K it is the main rod that is the one binds up. The bind is at the 2nd axle. There is a articulating joint on the main rod.What happens with mine is the main rod lifts up unevenly as the excessive slack in the entire mainrod /counterweight assembly begins to move when you change direction.  The main rod lifts and binds at joint on 2nd axle. The bind is severe enough to lock up mechanism, the motor cannot overcome bind. The only way to clear it is to reach in and straighten mainrod.  Tongue  I think the weak  suspension springs are allowing to axle to move up and it takes the mainrod with it. 
DOES R-T-R STAND FOR READY TO RUN OR READY TO REPAIR?Huh?
Why do I keep getting the BETA version of these locomotives.
I'm better now, my rant is over!!!
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bobgrosh

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« Reply #6 on: January 20, 2008, 06:55:33 PM »

Tommy.
Thanks for the additional information.

Like I said, That is only ONE off the things that causes the Kay to lock up.

I have not run mine other than on rollers and a short straight test track.

After your reply, I ran it back and forth trying to replicate your symptoms.
NADA, Mine does not lock up after changing direction, (short runs of 10 feet, pulling no cars, on Analog DC.)

As to the loose counterweights:
I checked mine, all eight. The screws are tight.
If I grasp both counterweights and gently rotate them by hand, they spin FREELY  ABOUT 20 to 30 degrees with respect to each other and then stop. The angle is pretty consistent from pair to pair as I compare each axle.

Looking closer at the screw head in the center of the counterweights I notice that all of the counterweights are allowed to rotate freely ABOUT 10 to 15 degrees with respect to the axle. Since each counterweight is allowed to rotate on the axle, the difference in the quartering between any two counterweights on an axle is twice the angle on one counterweight in relation to the axle.

When I first noticed this I thought it strange and decided that there must be something very different about the way the Kay is designed. I wondered if perhaps this was intentional and might make the Kay perform smoother on curves than other locos with rigidly attached drive-rods that must be "in Quarter"

The consistency of the angle of movement and the very freeness of movement made me also think that this was an intentional design. (Along with a statement from someone that there is noting wrong with the counterweights.)

Now keep in mind that I just got my Kay yesterday, and I am going through my checklist for new locos prior to installing DCC. I have reached the step where I need to make sure the loco runs smooth and is free of binds.

This is the check I was performing:
 I set the loco on OILED Nickle silver rail, attached an amp meter and applied 5 volts DC. I attached several rubber bands between the rear coupler and a track tie to provide a "springy" sort of stall on slippery rail. The loco should stretch the rubber bands and at some point begin slipping. Binds, or tights spots in the valve gear will show up as variation in current or oscillations back and forth of the loco.


I've gone  through the lubrication routine.

On the oiled track test, the Kay has a LOT of oscillations. About 2" back and forth. Not good but not as bad as some first attempts. I also notice a clunking sound once per wheel revolution and sudden jerks of some of the counterweights. I dropped the voltage a little till the loco stopped and raised it again slowly. The wheels did  move a little and then stalled. More voltage and the the motor started to hum. Back up to 5 volts and it is locked in a dead stall.

I repeated this several times and each time the locos locked, sure enough, the articulated drive rod is trying to push one counterweight backward. Moving the counterweight or lifting up on the drive rod at the offending axle frees the bind.

I removed the front counterweights. and examined them closely. The hole in the center of the counterweight is "D" shaped so it would be keyed to the axle which has a matching flat spot. If  the hole was the same size as the shaft, the counterweight would be held exactly 45 degrees from the counterweight on the other end of the shaft. Unfortunately, the hole in the counterweight is too large. The counterweight is not only free to rotate, but can wobble. Further, the flat on the axle extends further along the shaft than the thickness of the inner mating surface of the counterweight. No amount of tightening of the screw or adding washers will secure the counterweight to the axle because the length of the "D" shaped  end of the axle extends beyond the thickness of the counterweight at the hole. The counterweight will always be free to slide along the axle a very slight amount and the washers under the screw will always be bottomed out on the end of the shaft before any pressure is applied to grip the counterweight.

There are AT LEAST three options for a field repair.
    • 1 Install stainless shim stock on the flat side of the "D". Brass might also work, but being softer, it might not hold up long term.
    • 2 Drill and tap a hole in the hub in the counterweight and install a set screw so it engages with the flat on the axle.
    • 3 Drill out the counterweight and press fit a new hub with a proper size "D"

    I don't have the facilities to accomplish any of these here at my office so will have to wait till I return home next weekend to try effecting a repair. Unless of course, someone comes up with some other working solution.

    I continued looking for the cause of the oscillations by removing all the drive-rods and checking for binds. I found none.

    When I re-assembled the Kay, I decided to experiment with a temporary fix. Not having any shim stock handy, I sanded down some plastic cable ties to the needed thickness and pressed the counterweights with the pieces of cable ties back onto the shafts. This removed some of the wobble but the plastic is too soft to really do an effective job. This did make the Kay stop binding and reduce the oscillations of the Kay back and forth on the oiled track to about 1/2 inch. not perfect but OK for a while. This at least give me hope that the Kay can be made to start up smoothly.
    B0B[/list]
    « Last Edit: January 20, 2008, 07:00:41 PM by bobgrosh » Logged
    Curmudgeon
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    « Reply #7 on: January 20, 2008, 08:23:24 PM »

    Bob.
    This has been known for some time.
    I have not been authorized to discuss it in print.
    I am glad you have.

    I am, however, sharing it privately, even tho Stanley stated the problem does not exist.
    There is more to it, the axles being too long for one, but easily fixed.
    Brass is fine, trust me, I've been running with brass shims for 3 weeks.
    Ideally, in MOST situations, .008" is perfect.
    Be advised, the oillite bearings in the rods are brass, and they work.
    The die-cast counterweights are softer with the hammering than the brass that will prevent it from hammering.

    The "fix" (and to hell with "procedure") has been in for 3 weeks, but he who cannot keep his mouth shut let slip that Bachmann may have a fix coming.

    If you would like to e-mail me, I'll share the entire bit with you.

    The reverse gear locking issue is two-fold.
    One, make sure your eccentric is on right.
    Easy to change.
    Two, all LS Bachmann locos with adjustable valve gear seem to have a specific "sweet spot" for position, Climaxes being the most sensitive.
    Find what works for yours and leave it there.

    Thanks for getting me to log in here again.

    Now I'm logging out.

    TOC
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    jsmvmd

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    « Reply #8 on: January 20, 2008, 08:28:38 PM »

    I thought it had been rather quiet on the west coast. Glad to see you back.

    Best Wishes,

    Jack
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    Tony Walsham

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    « Reply #9 on: January 20, 2008, 08:54:26 PM »

    To be fair to Mr Ames.

    Yes, in front of at least 6 witnesses he did say categorically that the counterweight problem did not exist.
    It was then pointed out to him politely that there was irrefutable proof that it did exist.
    Two minutes later in front of the same witnesses he stated he had known about the problem all along.

    Make what you will of all that.
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    Tony Walsham
    Founding member of the battery Mafia.


    (Remote Control Systems).
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