'Can you supply a link or part number to this NWSL worm gear set?'
Scott, after a long technical conversation via email with NWSL (this was years ago), they suggested their set for the G scale 'Delton Doozie' would do the job. Their part # is 2119-6. It contains the worm and axle worm gear. The worm is a single lead.
Getting the OEM worm off the motor shaft was a major undertaking. I tried a gear/wheel puller. Nope. Then heat. No good either. I was very concerned about ruining the motor with too much effort or heat. I finally used a cutting wheel to slice the worm lengthwise.
The axle gear was a perfect friction fit. The worm needed Loctite to stay on the shaft snugly. The operational result was pleasing. However I declined to do three more trucks for the A-A set I was working on.
I believe the worm is highly heated at the factory, then press fit onto the motor shaft. You'd be best to start with a motor without a worm installed.
I'm with Jim. We have been asking for single lead worm vertical drives for years. It's one small change that has a significant impact.
As an aside. I've changed most of my road units to vertical drives. They last longer at the club for open house running, which lasts hours. With proper lubrication, truck/frame interface mount mods, and decoder adjustment. I get very good starts and slow speed operation.
