Sold March 2020 Back to Archive

The design was serialised in "Engineering in Miniature" magazine starting in 1984. By the time he wrote the articles, Ken had virtually finished his own model, proving the drawings in the process. It was an epic undertaking - many O&K drawings had been lost, believed destroyed after the war, so he worked the entire design up from photographs.

The prototype selected, works number 7000 was a 30hp engine supplied to Chiron Ferres at Chambery in 1914 - importantly it combined rack and adhesion working; a dog clutch allowing the engine to be run independently of the chassis and Walshaert's valve gear rather than O&K's own patent system, all features he wanted to incorporate in a model.

It produced a very attractive, technically interesting engine which is at home on the level working by adhesion as on the hills using the rack. Possibly the quirkiness of design (although more likely the daunting task of building such a complex piece of machinery) has meant there have been few completed - the late designer estimated 20 sets of castings had been supplied, I suspect only half of those have ever been completed.

This locomotive was completed in 2015. Built over ten years by a retired toolmaker, the man served his apprenticeship just after the war at a company in Cambridge making scientific intruments. He worked the rest of his life as a tool and instrument maker before retiring.

The silver soldered copper boiler was supplied new in 2009 - it is commercially built and CE-marked, complete with maker's paperwork and stress calculations.

I won't dilate at length on this one, the pictures opposite show the quality and quantity of work involved. It was constructed entirely in the builder's home workshop - where there's not an inch of bench or wall space unused around the Myford lathe and Swiss Mikron mill - with the exception of the 3DP steel rack gears which were cut over a period of several weeks at the local technical college before being hardened.

Machining, fit and finish is excellent throughout, as you might expect from a man with nearly fifty years experience in industry. No trouble was spared to make parts exactly as he wanted them - as one example, have a look at the steel press tool opposite - "a few weekends work" - simply to press the firehole door baffle plate (a part only ever seen when the door's open!).

Once finished the engine was run on air to check valve timing then set to one side whilst attention turned to the tender. Running on roller bearings, it has a steam connection to the locomotive to operate a brake on the rack cog beneath.

We've hydraulic tested the boiler in recent days and run the engine on air in the workshop (who could resist!) - there's some video of it here.

Complete with club documentation for the boiler's hydraulic test and a quantity of spares including gears, spectacle glasses and sundry small parts.