Bachmann 2-4-2 Driving Wheel Set - Gear Split

[Paul M]

Gentlemen:
Is this a common problem with ALL the Bachmann loco's? - Or is it if they are 'of an age'?
This seems to come up again, and again??

Which Bachmann loco's will this gear fit? - Sorry, I am not a Bachmann officiando.

Just thinking:
I could possibly buy a bunch, and hold stock here in the UK?

PhilP.

Sounds a plan

 

[Greg Elmassian]

Gentlemen:
Is this a common problem with ALL the Bachmann loco's? - Or is it if they are 'of an age'?
This seems to come up again, and again??

Which Bachmann loco's will this gear fit? - Sorry, I am not a Bachmann officiando.

Just thinking:
I could possibly buy a bunch, and hold stock here in the UK?

PhilP.

yes common on many

 

[Fred2179G]

Gentlemen:
Is this a common problem with ALL the Bachmann loco's? - Or is it if they are 'of an age'?
This seems to come up again, and again??

Yes this is a common problem for the 2-4-2, the Spectrum 2-6-0/4-4-0 and the Connie 2-8-0. Not so much the 4-6-0 as they sell a new chassis which gives you a decent upgrade. I think some of the geared locos had gear problems too. The gear seems to shrink over time and split.

Which Bachmann loco's will this gear fit? - Sorry, I am not a Bachmann officiando.
Just thinking:
I could possibly buy a bunch, and hold stock here in the UK?
PhilP.

Great idea Phil, but not practical. This gear only fits the 2-4-2 "Columbia" [tho it might fit the later 2-6-0 Industrial?] That loco is pretty flaky at the best of times, so why fix it - just buy another.

Bachmann now sells a replacement axle for the 2-6-0/4-4-0 and an axle with brass gear for the 2-8-0 in their parts store. NWSL offered gears, and I think the 2-8-0 gear will still work on the old axle, as will their 2-6-0/4-4-0 gear, but the new axles from Bachmann are different and won't take the NWSL gears. I suspect most people will buy the new Bachmann axles.
BTW - the Parts Store has reopened.

 

[PhilP]

BTW - the Parts Store has reopened.

In which case, the replacement axle with brass gear, is the way to go.. If you can get them form Bachmann Europe, so much the better..

 

[Fred2179G]

In which case, the replacement axle with brass gear, is the way to go.. If you can get them form Bachmann Europe, so much the better..

Sorry. The axle with the brass gear only fits the 2-8-0 - and it is extended to mount the outside cranks. The delrin gear from Jerry is really the only option I know for the 2-4-2 "Columbia".

 

[PhilP]

Sorry. The axle with the brass gear only fits the 2-8-0 - and it is extended to mount the outside cranks. The delrin gear from Jerry is really the only option I know for the 2-4-2 "Columbia".

There is the bodge-repair of pressing a piece of brass/copper tube onto the boss of the split gear, to hold it together

For extra security, you can cross-drill through the boss and axle to pin it in place.. - If you try this at home.. The broken drill-bit makes an effective 'pin'.
Whether I could ever get it apart, again, I do not know?

 

[Greg Elmassian]

Back to the beginning of the thread... reference picture of gear....

no room for a tube on this gear... too small to drill... you are SOL without a replacement gear...

just not enough "extra meat" to work with .....

 

[G Too]

Gear repair update …

I measured the split gear and determined that it was
Pitch: 0.8 MOD;
Number of teeth: 16
Pitch Circle Dia. (PCD): 12.8mm

I then ordered one from Buy 0.8 MOD - 16 Teeth - 5mm Face Width, B1-Type Precision Spur Gears - Brass | Save 13% | 500,000+ Components | Accu®

This gear has a grub screw for fixing to the shaft and has a bore diameter of 4mm.

Here's the replacement gear and the old one together.



The axle diameter was roughly 6mm. To fit the gear to the axle …

• The ridges that keyed the original plastic gear in place were removed from the axle
• The bore of the brass gear was opened to 15/64th
• A recess was cut in the brass gear between the grub screw and the teeth to allow clearance for the intermediate gear (which mates with the motor worm)
• The axle was lightly sanded in the lathe to reduce the diameter to obtain a good fit
• A flat was filed on the axle to assist keying of the grub screw

I was very happy with that and I had expected that would resolve the issue, since in previous testing without the wheelsets in place the motor worm turned the intermediate gear.

However, with the additional friction when re-assembled with a working axle gear present, I found that the mating of the motor worm gear with the intermediate plastic gear is very poor and that the gear tooth definition is too poor to carry load. This model had little use, so I can only assume that this was age related deterioration of the plastic.

At least the brass gear was cheap!

The intermediate gear can readily be removed by drifting out its axle. I can now give up, or try to measure the intermediate plastic gears ...

 

[Paul M]

A bit of a dilemma, but as you've gone this far. .........
It may be the camera angle, but is that wire in any danger of catching on the grub screw?

 

[G Too]

Indeed, but it's quite fun trying to find a solution.
The wire is below the level of the screw; on a final re-assembly I'd probably stick it to the chassis to ensure that it's out of the way.

 

[Greg Elmassian]

Unfortunately, the stock gearbox is pretty poor, strengthen one part, another part fails...

The worm gear is just too small, and poor plastic quality. The worm will eat the worm gear... but your brass gear sure looks nice!

Greg

 

[PreDreadNut]

I wish I would have read this before I purchased my Columbia Loco today:-(

 

[Fred2179G]

I wish I would have read this before I purchased my Columbia Loco today:-(

They aren't all dead on arrival. I got one a few weeks ago for a friend who wanted the wheels, and it worked fine.