how likely is it for the work gear on this ebay motor to be compatible with gears on our locos? is there that much variation in gearing at this size?
Did you mean “worm”?
Chances are the worm isn’t going to be in the right place on the shaft, IF indeed it would be on the shaft at all. Many brass diesels and steam locos have a universal joint or sometimes a silicone tube coupling.
PRR_N1_sam by Edmund, on Flickr
IMG_6626_fix (2016_08_17 08_08_12 UTC) by Edmund, on Flickr
Often the flywheel is pressed onto the motor shaft and the universal socket pressed into the bore of the flywheel.
I’ve seen a few cases where the worm is directly on the motor shaft but usually these are on small wheel base locomotives.
What locomotive are you planning to put this motor in?
NorthWest Short Line has some good information on their site about repowering, gearing and wheel sets for equipment:
Some worm (or spiral/helical gear) info here:
Cheers, Ed
i assume the worm(!) can be repositioned for a drive where the worm is on the shaft of the motor. I have a Gem 2-8-0 like below
I’d be a bit more concerned about the quality of the motor. If it’s a typical 3 pole straight armature, it isn’t going to run very well at all at slow speeds. At minimum, you’d want a 5 pole motor and preferrably a skewed armature for good slow speed operation.
Mark.
Also, a metal worm on metal worm gear is going to be a lot noiser than the plastic worm on the metal worm gear.
There was a really good article on chosing gearing in one of the old MRs - 50’s or maybe even earlier, but I think it was 50’s because plastic was an option for the gear material. Pretty much the tail end of the period when you pretty much HAD to DIY if you wanted it. Maybe it even was one of those “blue books” that was stuck in the back of the magazine. Very good read.
–Randy
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here’s a replacement motor from Bachmann which I assume meets those requirements.
But I’m still uncertain whether the worm will mesh properly with the axle gear on a non-Bachmann loco.
i have a brass boxcab and 0-6-0 with vertically mounted motors with metal worm and gear. The boxcab is quiet while the 0-6-0 growls. Still trying to understand why.
Dear Greg,
The most important factor that is crucial for (your) decision if the worm shown on your picture fits your locomotive is gear module. Module is designated as the unit representing gear tooth-sizes. If gear(s) in your locomotive do not have exactly the same module as worm on the picture, they will not mesh properly. Consequence is noise and premature wear and shortened service life of both worm and worm gear.
Here you can find very nice article about gear module:
https://khkgears.net/new/gear_knowledge/abcs_of_gears-b/basic_gear_terminology_calculation.html
From my experience here in Europe, at least two modules are used in model trains I have: 0,4 and 0,5. Roco uses mostly 0,4, while e.g. Fleischmann uses 0,5. So, gears from both manufacturers are not compatible.
I do not know which module are used by Athearn, Bachmann, Broadway etc. Maybe some other modelers can help.
I am not sure I understand why you want to buy this motor, but assume you want to replace open frame motor on the picture with new motor? If that is so, then it would be nice if you can use old worm, because if it is intact, it can be used again with new motor. In lot of cases a motor replacement will give very nice running, under condition all gears are ok and exactly positioned to mesh properly.
You can use old worm under condition that shaft diameter of old and new motor are the same. If not, and e.g. shaft of new motor is smaller, you cold maybe find a sleeve tubing to
Some parallel thoughts with Hrvoje:
In the US, the tooth spacing is called “pitch”, as opposed to “module”. Hence there’s 48 pitch and 72 pitch…
Another element is the tooth angle. Real worm gears have teeth that are not 90 degrees to the gear face. This angle may vary.
It really seems like a sticky tricky thing to find a worm gear that will match a worm. Or the other direction.
Ed
At least when just randomly picking up something like that motor with the worm already attached. Companies like NWSL sell matched sets. Then you know they will mate properly.
–Randy
Of course, this is a good approach because there is no doubt if gears fill fit to each other, but it can be tricky to remove gear from axle, and install new one, and quarter wheels properly.
But, if worm is still good, it seems is plastic - so it should not be so hard to remove it? If removed, just motor should be replaced.
Hrvoje
Thanks Ed - I did not know for “pitch”. I learned something new[:D]
Hrvoje
I ran into a similar issue some years ago and bought the gear planning documents from NWSL when they were in Washington. Now free on the Internet.
I bought the worm and worm gears and spur gear for the drivers.
They also sell reverse worms and worm gears.
The Puller made it easier. I used a drill press to put the gears in place.
I used the intermediate gear setup like the MDC locos used so the Sagami motor and flywheel was horizontal in the loco. You can see how MDC did this at HO Seeker page. The gear planning page shows this MDC gear setup.
I also have some MDC Roundhouse locos.
Worm driving a worm gear on an intermediate shaft. A spur gear next to it it drives the spur gear on the driver. I also had a Quartering tool.
Two locos. 45 to 1 and 72 to 1. Motors mounted in bath caulk. Very quiet.
I would recommend looking closely at the NWSL page for gears and motors, couplings.
Rich
i have.
the older Pittman motor shaft diameter appears larger than most newer motors. So either sims or replace the worm and gear.
so is noise due to metal worm on metal gear or isolating the motor from the frame?
NWSL sells adapter sleeves for shafts.
Ed
yes, not sims, adapter sleeves
Yes, adapter sleeves called bushings, shaft adapter, reducer. Download the gear planning documents and read carefully. I have used them many years ago. I also mounted motors in bath caulk like I said before and carfully adjusted for minimum gear lash and left it alone for twenty four hours. Not tight, just the required space according to NWSL. Metal worm to plastic worm gear.
Nothing touching the motor after the shell was in place.
NWSL had evrything I needed. A cheap dial caliper did evrything. No guessing.
Rich
are adapter sleeves for gears or worms?
Yes.
They’re for fitting things with bigger holes onto smaller shafts.
I’ve use them once. Because of the very slight slop in fit, they can’t run dead-concentric. For each use, then, it’s a matter of judgement. Is it concentric ENOUGH to work. Usually, you have no choice.
For my use, I was fitting a universal joint onto a motor shaft, so running a bit eccentric was no problem at all.
Ed
not asking about diameter, asking about length, the length of a hole and presumably the sleeves in a worm vs a gear
I was able make some sleeves with layers of aluminum and paper that make a tight enough fit.