Hi,
Since a month, I have a new Bachmann Spectrum 2-10-0 Russian Decapod with factory-installed Tsunami sound.
With good help from the forum I managed to take the superstructure off from the chassis and fix a rather bad bind in the mechanism (mainly, one of the pistons was too long, hitting the end of the cylinder, ok after filing it a little shorter), and it was running ok.
But recently it has started to be very hesitant on starting. The chuff rate increases as it should but the speed doesn’t. The wheels are not slipping. Much worse on grades or with a strin g of cars.
If I grabe the wheels and stop them the chuffing continues unaffected.
The back-emf is on, at the default settings.
My guess is that the belt drive, from the motor axle down to the worm axle, has begun to slip.
Does that seem probable?
And if it is, what can I do to fix it? Can it get looser with time and need replacerment?
Or has some grease crept on to it? If so, what would be the way to clean it?
When I had the superstructure off, it seemed to be more difficult to take that part apart to access the belt.
Thus I wish there’d be a way to fix the slip without doing that.
I don’t remember if one could get a glimpse of the belt from below.
One thing to keep in mind is that the Spectrum engines (unlike say BLI engines) don’t have any cam or other physical connection to the wheels that triggers the “chuffs”. All you can do is use the CV’s to program the decoder to get the chuffs as close as possible to be in synch. So the fact that you can hold the engine so the wheels aren’t turning and the “chuff-chuff-chuff” continues as normal doesn’t mean that something mechanical is wrong.
If you set the chuff rate to be correct when the engine is running light, it won’t be correct when the engine is pulling a train, as the drag of the cars will make the drivers turn a little more slowly, even though the chuffs will continue as normal. Best you can do is a compromise so the chuffs are slightly more than 4 per revolution when moving light, and slightly less with a train.
Also the Tsunami does have Back EMF, but there are several settings you have to adjust. It’s possible to in effect have BEMF turned on, but set so that it really doesn’t affect the engine.
But perhaps I didn’t describe the problem right.
It is not a matter of chuff sync (that’ll be a later chore to improve on that).
I just mentioned the chuffing as an indicator that the motor is running, quite normally.
The loco has lost most of it’s pulling power, wasn’t too great before, but now much worse.
When I stop the drivers with my hand I can also feel vibrations that suggest the motor is running, That’s why I suspect drive belt slip.
Don’t know about the 2-10-0 but the Bachmann 2-8-0 used a “toothed belt” so the belt is not slipping. If something is slipping it would be the pulley on the shaft.
One of the reasons I have given up on Bachmann locos I think is this problem. I sold a 2-10-0 to a friend which subsequently stripped its gear and have a 2-8-0 in bits because the main drive axle gear stripped and I thought similarly to yourself that the belt or a gear was slipping. I got a couple of NWSL gears and will get around to fixing the problem on both locos … when I feel a bit better disposed to the brand and I have the time.
The gears on mine basically chew in the middle and gives an erratic motion to boot. I hope the effort with the NWSL gears will be worth it… I love the look of the Bachmann engines but stories like yours and events like mine are not encouraging me to look at buying any others,
Bachmann supposedly uses a cogged belt so it is highly unlikely that the belt is slipping. The gears that the belt turns may be slipping or not properly meshed, or a gear on the motor shaft is slipping.
Send it back to Bachmann and have them repair it before you break something and void your warranty.
Yes, that’s right, on the exploded parts view I see that at least the pulley on the wormgear axle has a toothing. The pulley on the motor axle isn’t visible but most likely it is toothed the same way. So it isn’t a matter of belt slipping.
What remains would be that one of the pylleys is slipping on its axle, or the worm.
Or, it is the gear on the driver axle.
I’d be happy if the slip is on the driver axle because that one is the easiest to access.
Sending it back to Bachmann? Well, with an ocean between (Sweden), it is not the most attractive option.
So I’ll probably have a go at it myself, not today though.
Right, could be a bad gear too. Especially if it is plastic, maybe it got badly worn in the first phase when I thought the bind would be overcome by break-in running. As I recall though, the loco ran without the current slipping problem for a while after I fixed the bind.
The build of this loco is new to me (I’m recently back to MRR after almost 1/4 of a century), maybe it has become a standard nowadays,
I mean that the boiler and firebox is all one big clump of cast metal, well, two halves of it, with the motor set in it, and then all this sits inside a plastic skin with all the details on,
I don’t know yet if it is possible to get the skin off without first taking the whole top off from the chassis.
Hope it does. As you suggest, that would give a better view of the mechanism, perhaps even in running.
Thanks to all,
Sverker
More than likely it is the gear on the motor shaft that is slipping. I fixed a couple of my Spectrum locos by pulling the flywheel off and super glued the gear on the shaft and then pressed the flywheel back on. Unfortunately one only lasted a short time and I have not taken it apart to do it again. The other is still going strong though. Maybe I will do some measuring or maybe make my own gear someday.
Thanks Pete for sharing your experiences.
Makes sense. I’ll see what I find once I get in there, will be a while before I get time to sit down with it though.
I’ll report on it.
I seem to remember having heard about what to do when a press-fit gear-axle is slipping.
Should be a common old problem – with a standard solution, right?.
Super glue, yes, but isn’t it possible to rough up the axle a bit first. Axles are often shining smooth, killing the shine would allow the glue to get a better grip?
How? If the axle is hard steel a file might not do it, maybe emory paper, rubbing along the axle, or could a Dremel with a steel brush do it? It will be important of course to not reduce the already too small diameter of the axle.
Or what are the tricks of the trade?
Sverker
Swerk, on another thread just in the past day or two, Dr. Wayne has talked about rolling the shaft between two metal milll files to force some of the metal at the surface upward and some down. This roughing process, called ‘upsetting’ according to Dr. Wayne, works to increase the diameter of the shaft by just a fraction of a mm.
See “Gear slipping on metal rod” several threads below.
Thanks Crandell for the hint!
There they are, all the tricks of the trade I was figuring.
Now I just hope that once I get the mechanism opened up it will turn out to be just that, a gear/shaft slip.