I’ve been impressed with the Union Mills locos since my first purchase a few years ago. So reliable and such great pulling power. Being unimpressed at the prices being paid for second hand ones, I set up the Facebook group - Union Mills N Gauge Model Railway Appreciation group to raise awareness. 

Colin has kindly sent me all the A5 loco sheets. I’ve scanned them, pasted the text into Word and then corrected all the scanning and format errors caused by the software. Whilst the document has been run through Microsoft Word’s spelling and grammar checker, if you do find a section that doesn’t make sense then please do let me know. I know that the software lost a few words along the way. I hope you enjoy these A4 documents, that Colin took the time to create. 

Mark Ellis 

by Colin Heard 

Production of the range of Union Mills 'N' gauge model locomotives began in the autumn of 1994 with the first version of the J39. This was fitted with my first design of tender drive in which a can motor drove a longitudinal shaft via a spur gear step down, the shaft having a worm at each end which drove the front and rear axles. This proved noisy due to the initial stage of spur gears and was not fitted with traction tyres. 

In 1995 a new tender drive was designed in which an initial worm reduction via a steel worm drove a series of nylon spur gears to all three axles which had traction tyres. This continued in use until around 2002 when a new design of tender drive was created using a double shaft motor with a worm on each end driving via an idler shaft to a spur gear on the front and rear axles. The centre axle was not driven. 

In the first instance Japanese motors were used, but then I went on to custom made Korean Samhongsa motors. Initial experiments were made with carbon brushes but in the end, I settled on the metal brush motor that has proved very reliable if used with an electronic controller like Gaugemaster. Brass worms were used with the initial lot of double shaft tender drives, followed by nylon worms. 

At the end of 2014 another tender drive was designed, this took advantage of modern developments in motor technology in China and used a smaller motor with excellent characteristics for slow running and I reverted to brass worms. This new motor is lower and mounted in an offset position and has enabled the lower GWR tenders to be modelled although it has also been adopted for all the other tender drives. 

Below is a list of all the models I have made over the years, but not in the order in which they were made. Some of the older models like the J39, D20 and B 12 have either been partly or wholly re-tooled to bring them up to the latest standards.; All models were made in both B.R. and Grouped liveries apart from the City of Truro which only had one livery. 

When the D20 and B12 were introduced, they used bogies with a slot that slid from side to side under a rubbing block. This was fine but called for precise adjustment to give good results. Both bogies were later changed to the pivoted type with a phosphor bronze spring to give downward pressure. When first made the D20 came out 2mm too high! The last to be made in that form was in 2003. The chassis was then modified in 2007 and lowered and fitted with the new type front bogie. The later model is correct and a better model.

In 1997 125 D20s were painted in North Eastern green and sold under their original designation of R Class. They represented a 'special edition' the only one I have ever issued and each had a numbered certificate. In 2009 I was persuaded by an N Gauge Society member, Jeremy Burrows, to make him another 50 R Class with the new improved chassis, these he sold himself. In 2018 some spare bodies were used to make several more.

The PDF list of Loco release dates, and colours and numbers used can be downloaded here

Union Mills loco production list 2022