Last Updated: 16 June 2025

This guide covers the following models:

  • Union Mills Class J39 64736 in BR Black

Union Mills Tender Drive Conversion

This later version uses a dual shaft motor, powering only the outer tender axles - the middle axle is unpowered. A small decoder can be fitted inside the tender without milling, for detailed instructions on how to do this, follow the Union Mills Class T9 guide.

The older tender drive can be identified by several visible cogs on the underside of the tender rather than just two. If you have this model, refer to the Union Mills J39 (old tender drive) page.

You can see a comparison between the versions of this model in the photo below:

Convert Union Mills Class J39 loco to DCC Convert Union Mills Class J39 loco to DCC