2-8-0 Slight Surging

[herbyguitar]

Hi. I may be too picky but I just received a Bachmann 2-8-0 a few days ago and while running it for back and forth while playing with CVs I noticed it doesn't want to run very smooth at very low speeds. It seems to surge slightly. It's also noticeable at slightly faster speeds also but not as noticeable. You have to look hard to see it. It seems to conform with the rotation of the motor shaft. Like I said, I may be too picky but after reading through some posts here I thought that I may have a small problem.

I managed to force it to smooth out almost totally but had to add "way" more BEMF than I would like to. I have "CV 209, Kp Coefficient" set to 200 to get it to smooth out. This seems a bit severe to me.

Thinking there may be a problem in the belt system, I pulled the running gear and boiler off to see what could be causing this and found nothing out of the ordinary. The belt had slight slack in it and everything seemed to be in order but I'm not too sure I would know what to look for.

Any help would be appreciated.

Herb Watson

[toyman]

From another board on which I am a member, it was suggested to check the frame halves around the area of the belt to see if there was any contact. It was also suggested to clearance the frame a little and add a very small amount of lube to the belt.

HTH,

Joe

[Yampa Bob]

Unless there is something really wrong out of the box, I don't adjust anything until running the loco for about an hour, forward and back, at varying speeds.  They all need a break in period.

My motto is, if it ain't broke, don't fix it.

Bob

[James Hail]

If it surges once per revolution (timed with the wheels) then its a driver quarter issue and it will not Break in.

Jim

[herbyguitar]

It seems to surge with motor revolution. I had it apart to look. There's nothing kanging up. The only thing I can think of is that the belt drive system has very slight fluxuations in the alignment and there's really nothing to do to fix it. It looks like it's just an inherent issue with loose belt drives. If the belt was smooth and had a slight friction fit it would probably run smoother although the starting voltage would be higher.

[James Hail]

Could be a stiff spot from sitting in the belt.

Run it till it pukes .......maybe it will loosen up.

It took me 3 tries to get a good 2-8-0.And it required work too.

Jim

[Jim Banner]

I doubt if the problem is with the belt if the surge occurs once per revolution of the motor.  Belt problems usually occur when a belt takes a set from sitting in one position for too long and the surge occurs twice per revolution of the belt.  It is possible that one of the belt sprockets is mal formed.  Slipping off the belt and checking the insides of the sprockets with a good magnifying glass may reveal something out of the ordinary.  And while the belt is off, spin the worm gently with a finger to see if you can feel any binding in its shaft or bearings.  Use the magnifying glass in this area too, just to make sure that no flash is impinging on the worm once per revolution.

[WoundedBear]

My new Spectrum 4-6-0 had a bit of a surge once per revolution as well. A close external inspection showed a bit of flash on one crank-pin and the link rod wouldn't pivot over top of it smoothly. I touched the face with a file and things are improving. I also gave it a light external lube.

I only received this loco last Friday in the mail, so there is not a lot of run time on it yet. I believe these belts do take a "set" when the locos are sitting and some running should loosen this up. If it's not silky smooth with a bit more run time, I will open the gear train.

Sid

[herbyguitar]

So Sid? How's the break in going? Any improvements?

Herb

[#94]

Besides the 2-8-0, are there other Bachmann steam that use this belt drive? Overall is this a good system compared to the worm gear? Herb, has this surging become less now that you have had more time to break in?

[WoundedBear]

To #94....as I stated....the 4-6-0 Ten Wheeler uses the belt.....not sure which others do. Maybe Gene can chime in here.

Charvell.....The loco is smoothing out. I put a Lenz BEMF decoder in it and she runs beautifully at slow speeds. The tender has the same derail troubles as the 2-8-0, and with the tender jammed full of decoder, I'm not sure where or how I'm going to add weight.

At the moment, I'm still tweaking the wires and I think the forward tender truck is mounted too tight. I want to open the tender again and give a little more play to the truck pivot.

But, yes......the surging is going away....everyday it runs, it gets better.

Sid

[James Hail]

The belts are the first stage of the gear reduction......it then drives a worm shaft to the drive wheel gear.

Once lubed (bushings) and broken in they are ok.

[Yampa Bob]

Jim,

"Run it till it pukes"

May I quote you at times?  I like that, maybe Bachmann should put that in the instruction manual  LOL

Bob

[James Hail]

Shure Bob.........quote away 8o)

Warning Rant ahead.....One madmans view of the cosmos....In response to reading posts that suggest we just fix things
and accept defects and lack of quality.

I decided i am going to let it(motive power) run next time i get a "bad" one and then send in the remains to be replaced.

I can fix alot of stuff...And i enjoy it...And have fixed alot of "B's" Stuff.I own mostly Bachmann,due to price and replacement policy....and im comfortable fixing/tuning  them.But i like knowing i can get another if all else fails.

Id rather fix than return........I love the challenge......But some things like out of round wheels....off center gears and axles ect .......are Un-fixable without major tools and parts.And such parts should never leave a modern factory in this day and age.

One off center gear or wheel ruins even the best $3000 detailed loco,Or $50 trainset.

I once built a MDC Roundhouse kit that included a herald Sagami motor from the factory.........Great until i found the wheels to be round as eggs and the axle gear was off center...Sagami or not this loco was crap and it was their fault.And they wanted to blow me flack about it........Fine ....I never purchased nor will purchase a MDC product again.....as much as i liked kit locos.

Avoid MDC kit locos........Unless you have a lathe and don't mind lowering the ride height of the loco after you true the wheels up.


ISO 2 billion point 45 and yet our factory cannot machine a wheel on center.

My son has $3.00 toys with wheels truer than most Steam engines.Its a shame.

Hes got a micro aaa cell powered toy train with switches that work properly and wheels that roll true.....and the entire "layout" was less than $40.And a 6 year old can run it and it works fine (he has no tools to tweek things).


........sorry guys.....But we really should not accept crap products from anyone.

Do you pay a roofer hard earned cash if your roof still leaks?And figure you will just get the ladder out and "tweek it" yourself as usual.

many edits later I quit........

Jim