Replacement gear Hallmark M-190

[Sdynamo]

Hi All,

I'm trying to replace a cracked nylon gear on a Hallmark M-190.  I found the discussion and chart on this https://www.therailwire.net/forum/index.php?topic=51338.msg697300#msg697300 for the gear I need, but I don't have a way of getting in touch with @genemaddox - he has not been online since 2021.

My worm gear is roughly .165", so it looks like I have the regular, non-high speed M-190.  My broken gear is about .221" using my cheap calipers, so it looks like I need the "14T, .222" OD, Tower Double Spur Large Gear."

Does anyone know what MOD this equates to for NWSL gears?

[spookshow]

Assuming it's still valid, Gene's email address can be found here - http://www.spookshow.net/brass.html

-Mark

[u18b]

I had to replace one on this loco last year.
Back then, Gene still had replacements.

[mmagliaro]

14T, .222" OD works out to mod 0.35.

mod x (number of teeth + 2) = outer diam   (all in millimeters)
So .222 x 25.4 = 5.6388 mm

5.6388 / (14+2) = .3524, so I'm calling it mod 0.35.

HOWEVER, the gear may not be a metric module size.   It might be specified as diametral pitch.
P = (number of teeth + 2)/diam = 72.072    (16) / .222 = 72.072

Mod 0.35 and Dp 72 are  equivalent and in fact, NWSL's page lists them as "the same".  When looking for gears,
you will probably find that gears listed as "Mod 0.35" are rarer than Dp72.

[Sdynamo]

Thanks Max!  Going through the NWSL site I figured it was a .35mod/72 dp gear. I ordered the gear that was close but it turns out I need to ream out the ID on it.

Fortunately I hit ahold of Gene Maddox and he has the gears. Thanks all!

[atsf_arizona]

Great to hear that Gene Maddox is still around.   He is a gift to us all, for having parts for those old but valuable Bobby Hall Hallmark models.