GS-4 re-motor project update

[strummer]

Now to continue the "how to screw up a loco for dummies" class...

Carl

... ...

Mark in Oregon

[peteski]

More than you (as a model railroader) ever wanted to know about gears: https://en.wikipedia.org/wiki/Gear . For pitch info look under the Nomenclature section.  Basically it is how fine the teeth are.  If you were to place the original GS-4 worm and the other  Kato worm next to each other you would notice that the GS-4 worm has finer spacing between the spirals than the other Kato worm. So the meshing between the incorrect work and the worm gear would be like trying to use a wrong pitch nut on a screw. Trying to mate a 10-24 nut and a 10-32 screw. If you force them together, there will be thread damage.

[victor miranda]

gear module is a standard way to reference gears.

it is a metric measurment in that it is used with the
module number to generate gear measurements.
the english measurement equivalent is called DP.

the smaller the module number the smaller the size of the teeth.

wiki...
https://en.wikipedia.org/wiki/Gear
look toward the bottom.

to go on to what I will call subtleties.

when worms and wormwheels do not fit...
usually the wormwheel is worn by the worm, some times quite quickly.
The more annoying part of that wear is that it is often free of noise.

noise at the worm is usually from the worm thrust slapping
the worm/shaft against the bearings.
as unhelpful as that is....

What you want is a way to reduce the noise.
if you can, adjust the worm and its wheel to the quietest place.
often that is too close for proper operation. Then you lift the worm off the wheel a tiny little bit.
think of it a clearance for the grease.

then....
make sure the power going in is even and that the output is free.
once that is done, what little noise left is from the worm wheel backlash.

which leads me to one last item.

with n-scale gears and bearings it is hard to remove all the noise.

victor

[mmagliaro]

Peteski and Victor gave good explanations of module.

In our N Scale locos, the most common module is 0.3 (from what I've seen).
Old stuff, like Rivarossi and Trix steam, has 0.4 (coarser teeth).
Your GS4 has 0.25.  I think that's the first one I've seen like that.

When I regear the Trix K4, I replace the worm and worm wheel with 0.3 module (replacing the 0.4).

There is a simple formula relating diameter, module, and gear teeth.

mod x n  +   2 x mod = diameter
n = number of teeth

Here's an example:

So a Trix 0.4 module gear with 15 teeth gives you:
0.4 x 15  +  2 x 0.4 =  6.8mm diameter

If I replace it with a module 0.3, 28 teeth:
0.3 x 28  + 2 x 0.3 = 9.0mm

So the replacement gear is 2.2mm larger, but it fits in that case.
It is only 1.1mm larger radius, so I only need 1.1mm more clearance in the frame to fit,
and as it happens, there is enough in the Trix K4.
And I get 28 teeth in almost the same space as the old gear had only 15, so
I get a big reduction.