Spectrum 2-8-0 flywheel

[secondhandmodeler]

I have recently purchased a Bachmann spectrum 2-8-0 to use on my dc layout.  I know it says that it has a flywheel, but it runs like it dosen't.  It seems to start like my older steamer without a flywheel.  Do steam engines just run differently then a diesel?  My old athearn diesels start up nice and smooth with flywheels.  I have run the new engine for about an hour total. Do I just need to break it in a little more?  Sorry for the newbie question. Any wisdom on this question would be greatly appreciated. Thanks

[msowsun]

The Bachmann Spectrum's 2-8-0 flywheel is too small to have any noticable effect. Most steamers with flywheels also have very little effect.

[secondhandmodeler]

Thanks for the repy.  I guess that's a reason to use dcc instead of dc.

[Railphotog]

A flywheel has very little to do with how an engine starts.  It is mostly used to help in "coast" over bad spots in the track where electrical pickup may be a problem.  The momentum of the spinning flywheel is supposed to keep the motor turning if it cuts out due to electrical problems. 

 

 

[secondhandmodeler]

I was under the impression that flywheels were to help with not having "train set" start ups.  I guess you learn something new every day.

[loathar]

What type of DC controller are you using? IIRC that has more to do with eliminating jack rabbit starts.(along with motor quality)

I have 2 Bachman B 23's. One has large flywheels and the other has tiny ones. (same motors) There's a big difference between how they run and stop, but not how they start up.

[secondhandmodeler]

It's an oldie but a goodie.  An mrc 501 , I think.  It's old that's all I know!   The engine just seems to take more juice to get going.  It goes nice and slow in pulse mode though.

[selector]

I find that my locos will stop on a dime if they run out of power for more than half a second or so.  This happens virtually never, but I have had occasion to see my BLI steamers stop dead, and with a slight nudge come back to life and accelerate prototypically all over again.  Maybe if they all had 1kg of rotating mass it would make a big difference, but I don't see that the flywheels add much to the operation of them.  But, yes, I certainly agree that they should do very little on start-up.  The idea is that they are meant to help propel the loco over the "bad spot" once underway with a bit of speed.

[secondhandmodeler]

I really appreciate everybody's answers to my newbie questions. It's probably the controller I'm using.  I just thought if my twenty year old coffee grinders started so well, the bachmann would too.  I guess I can't ask for  too much with the old controller and brass track.  Yes yes I know, brass track is bad!  Thanks again.

[loathar]

I think the older motors take more juice to get them going. The newer ones don't. This could account for the difference. It might just need a break in period too. When you run it slow, does it run smoothly or does it tend to jerk a little?

[secondhandmodeler]

It seems to run fine once it's going.  Don't get me wrong, it doesn't jack rabbit start.  It just doesn't seem as smooth as I thought it would be.  Maybe I need to clean my track.  I suppose it's possible that the bachmann is geared a lot differently than the athearns.  That would make sense.

[BRAKIE]

I was under the impression that flywheels were to help with not having "train set" start ups.  I guess you learn something new every day.

 

Indeed thats the theory.Thats why we have smooth running locomotives.

Take a locomotive without a flywheel and you have a "zip" start.Even a small flywheel helps.

I suspect the quick start might be due to the drive belt the 2-8-0 has.

[secondhandmodeler]

I was a little confused when I bought it.  It said belt drive and fly wheel.  I thought that sounded a little different.  I believe David called it a cog drive?  Oh well, I like the engine,  I was just concerned that something was wrong.  I figure I'll beat it into submission(break it in better)!  Thanks everybody for the information.

[faraway]

I've experiance with a German engine (BR92 from Trix) that has fly wheel and belt transmission.

The belt transmission completly offsets the effect of the fly wheel. The belt need too much tension to work to give the fly wheel a chance to turn the mechanics.

Only a good DCC decoder can make the engine apear smooth. 

 

ps. I have two Spectrum 2-8-0 on order. I wonder if is was a good choice... we'll see:-) 

[Virginian]

As noted, small flywheels do more for the sales brochure than for jackrabbit starts.  If an engine will not start smoothly because the motor and/or drivetrain is at fault, DCC isn't going to do squat for it.  All DCC does is control where the motor gets the DC voltange from; directly from the rails vs. from a DCC controller.  You said that it starts smoothly in pulse mode, so what's the problem?  Why not use pulse mode?  That is what pulse mode is there for.  It will probably smooth up a little with more break in.  Start in pulse and then switch over. 

The belt drive does not have huge tension on it.  It is a miniature timing belt (i.e., it has teeth on the belt) so it doesn't rely on tension to maintain engagement.

[BillyDee53]

If you are sure you are never going to use DCC in the future, open the tender, rip out all the electronic junk, throw it away and re-wire the tender trucks to the motor.  This will lower your starting voltage by 3 volts and eliminate about 95% of the problems associated with Bachmann engines.  While you have the loco and tender apart, file the little latching lugs off the male connector plugs, and NEVER seperate the plugs by pulling the wires.

[secondhandmodeler]

I think I'll just deal with it for now.  I like the scenery more than operations anyway.  This is my first layout since I was twelve.  Now seventeen years late, here I am "playing with trains."  I bought the engine thnking some day I may switch to dcc.  That would probably come with the next layout though.  Thanks again to everybody who shared their wisdom with me!

[rrebell]

It's an oldie but a goodie.  An mrc 501 , I think.  It's old that's all I know!   The engine just seems to take more juice to get going.  It goes nice and slow in pulse mode though.

Thats your problem, get a newer pack or it will give you will continue to have problems, I like my 2500's from mrc, still inexpencive like 15 to 20 bucks on the right ebay auction but work almost as well as the newer ones. The 501's had a taper whond (spell cheak please) reostate and the one i mentionted as well as others from that time period are mostly electronic as I understand it, anyway I got three and they all work great

[Darth Santa Fe]

I was a little confused when I bought it.  It said belt drive and fly wheel.  I thought that sounded a little different.  I believe David called it a cog drive?  Oh well, I like the engine,  I was just concerned that something was wrong.  I figure I'll beat it into submission(break it in better)!  Thanks everybody for the information.

Incase you don't have the original diagram of the engine, here's a link to one showing how the whole cogged belt drive is built.
http://hoseeker.net/assemblyexplosionbachmann/bachmannspectra4-8-0.jpg

[secondhandmodeler]

HEY, THESE THINGS READ LIKE STEREO INSTRUCTIONS!  Just kidding, I actually understand stereo instructions.  Thanks for the help.  I think I might need some ungrading.  Just not sure how far to ungrade to.

[Idaho Trains]

I've experiance with a German engine (BR92 from Trix) that has fly wheel and belt transmission.

The belt transmission completly offsets the effect of the fly wheel. The belt need too much tension to work to give the fly wheel a chance to turn the mechanics.

Only a good DCC decoder can make the engine apear smooth. 

 

ps. I have two Spectrum 2-8-0 on order. I wonder if is was a good choice... we'll see:-) 

 Faraway,

I have my 2-8-0 spectrum now and have had it for about 2 weeks. I purchsed the one with the tsunami sound decoder in it and love everything about this locomotive. It is excellent running and great sound. It starts very smooth with low voltage. It surely beats my BLI 2-10-2 with QSI decoder. I will see how that one is this week when the sound chip upgrade for the QSI arrives. I was told that will take care of a lot of the running issues with the BLI 2-10-2.

 Jeff

[jeffers_mz]

Though it seems to be overlooked in this thread, Bachman locomotives, even Spectrums, have severe quality control issues from the factory.

That said, ALL my Spectrums run. perfectly.

 

That's because I KNOW they sell bad ones, to the point my LHS calls them "Botch-mans".

 

When I need one, it comes out of the box at the LHS, and goes onto their test track. When I SEE it running perfectly, forward, reverse, low spped, high speed, stopping, starting, and when I INSPECT it closely for fit, finish and detail, and everything meets my approval, it comes home with me.

 

Otherwise it goes BACK IN THE BOX and I do without, or , more often, the LHS orders some more and they usually order quite a few so that at least one will look and run right.

 

If you insist on quality, you will get it. Whatever Bachman's problem is, they do get it right, in my experience, about half the time. That's based on experience with exactly ten Spectrum steam locomotives. Not a huge statistical pool, and not a generalization based only on one good or bad experience either, somewhere in the middle, but my assumptions are bourne out by what others have to say about the breed too.

 

Pick and choose, and you'll get a beautiful locomotive that runs like a swiss watch.

 

Buy without testing, and you'll get a lemon, frequently.

 

Your money, your choice.

[doctorwayne]

I have to agree that your power pack could use an upgrade.  I have quite a few Bachmann 2-8-0s, and all start and run smoothly on straight DC.  I left the flywheels in mine, but I don't think that they do much good.  I did remove the flywheel and the circuit board from my Proto 0-8-0, and was able to add enough weight in their place to more than double its pulling abilities.  Even though it is an early version with no tender pick-up, I have had no problems with it stalling on turnouts.

 

Wayne

[Isambard]

My Grizzly Northern has eleven Spectrum steam loco's ie four 2-8-0's, four  2-10-0's, one  2-10-2, a 2-6-6-2 and a three-truck Shay. All are now very smooth runners, some straight out of the box, others after a bit of tinkering, and in one case an exchange with Bachmann. I believe the Spectrums are very good value for money considering the level of details provided, comparing favourably with many brass models. 

Regarding the cog belt drive, I've been told that the belt design is borrowed from satellite servo-mechanisms and is very robust. The cog design, like a timing belt or chain drive, allows no slip in response to sudden stops or starts, unlike conventional flat or vee type belt drives, which means that if the motor stops or starts suddenly so does the drive system, despite the flywheel. This can result in jerky behavior if electrical power is lost momentarily e.g. faulty track or switches, DCC glitches etc. In the case of DCC this can be compensated for, if a problem, by building in a bit of momemtum to CV3 and CV4.

 

[ereimer]

My Grizzly Northern has eleven Spectrum steam loco's ie four 2-8-0's, four  2-10-0's, one  2-10-2, a 2-6-6-2 and a three-truck Shay. All are now very smooth runners, some straight out of the box, others after a bit of tinkering, and in one case an exchange with Bachmann. I believe the Spectrums are very good value for money considering the level of details provided, comparing favourably with many brass models. 

Regarding the cog belt drive, I've been told that the belt design is borrowed from satellite servo-mechanisms and is very robust. The cog design, like a timing belt or chain drive, allows no slip in response to sudden stops or starts, unlike conventional flat or vee type belt drives, which means that if the motor stops or starts suddenly so does the drive system, despite the flywheel. This can result in jerky behavior if electrical power is lost momentarily e.g. faulty track or switches, DCC glitches etc. In the case of DCC this can be compensated for, if a problem, by building in a bit of momemtum to CV3 and CV4.

(bold added by me)

you're right , the whole point of adding a flywheel is to stop the motor from stopping or starting suddenly , if , for example , the engine passes over a turnout and momentarily drops  electrical contact . the problem we're seeing here is that the flywheel isn't heavy enough to keep the motor spinning long enough to have a noticeable momentum effect . your DCC fix for the problem works well , unfortunately the original poster is running DC . i think the only fix for DC would be to add a heavier flywheel and i don't know if that's possible in the bachmann

[fwright]

....This can result in jerky behavior if electrical power is lost momentarily e.g. faulty track or switches, DCC glitches etc. In the case of DCC this can be compensated for, if a problem, by building in a bit of momemtum to CV3 and CV4.

Sorry to disappoint.  Setting all the momentum in the world won't help a DC or DCC-powered motor keep turning when power is lost, even momentarily.  Good decoders have "keep-alive" circuits that keep the decoder from resetting during a momentary power loss.  But unless you have a special add-in circuit like the Lenz designed to keep the motor going for a second or two (involves adding fairly large capacitor(s)), the flywheel is the only defense to carry you through the track power loss.  As has been pointed out, flywheels tend to be less effective on steamers due to extra friction from  from side rods, valve gear, longer rigid wheel bases, and tender drag.  And flywheels on steamers are usually smaller than on diesels to begin with.  For a flywheel, adding diameter is the quickest way to build rotational inertia.  Adding length and total mass don't increase inertia as much as moving the mass away from the axis of rotation does.

my thoughts and experiences

Fred W

[boxcar_jim]

I think Fred W is right. The Bachmann 2-8-0 I kitbashed to better represent a B&M K8c ran beautifully on DC. When I initially put a (budget) DCC decoder in it, it started mis-behaving - stopping and starting with a jerk, hesitating at the slightest bit of dirt on the rails, etc. The flywheel just isn't big enough in diameter, no matter how much momentum you program in ....

.... I switched the budget decoder for a Lenz Gold with the UP1 module and now its my best running steam loco.

[SteamFreak]

Yes, it has a flywheel, not 2 of them like even the smallest diesel does. Diesels benefit from this, as well as not being encumbered by the additional friction of running gear. The more flywheels and the larger their diameter, the greater the momentum. That's why the old Athearn BB FP45's and the Proto 2K PA's will coast into next week.