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January 2010

Mac Muckley's de Winton

by Marc Horovitz
History
The history of de Winton locomotives is discussed here. These tiny locomotives were used primarily in the slate quarries of Wales.

The model
This locomotive was scratchbuilt by Mac Muckley of Britain. I don't know when it was built but I believe it was in the mid-to-late 1990s. I acquired it in 2001.

It's a beautifully made engine, with a vertical, single-flue boiler lagged in wood. The boiler has cross tubes in the flue, low, near the fire. Fittings on this tiny boiler include just about everything: a throttle, pressure gauge, water glass, Goodall filler valve; blower, and safety valve. The steam line runs from the throttle to a displacement lubricator (with a drain!), thence to the cylinders.

The steam motor is a pair of double-acting oscillators. The steam motor is geared to one axle in what appears to be around a 3:1 ratio. The other axle is powered by the side rods. A rotary reversing valve, controlled by a nicely made reversing lever, is built into the cylinders' port block.

This locomotive is gas fired. The storage tank is at one end and the gas-control valve is at the other. The burner amounts to a tiny poker-type unit built into a pan (a copper plumbing fitting) below the boiler. This engine is unusual among gas-fired locomotives in that it requires a draft to get steam up. The fire must be started with a suction fan, after which the blower takes over to keep it going.

The run
I oiled the engine all around, drained the lubricator, and fed the engine its various fluids. Before lighting the fire, I popped a fan into the stack and turned it on. I then turned on the gas and struck a match. As soon as I did this, trouble lurked. The fire would not stay lit. After multiple attempts I disassembled the burner and blew out its components with compressed air to clear any blockage, imagined or real.

With the parts back together again I gave it another go. Things seemed a little better this time. The engine raised enough pressure for one lap before the fire was gone again. After many more attempts, trying different things all the while, I finally had to call it a day -- hence, no video this time.

I'm wondering if Denver's altitude might have something to do with the problem. I know that it has affected other engines. Perhaps a different type of burner would be better. This engine will have to go into the backshop, where it will find plenty of company.
Specifications
Builder Mac Muckley (UK)
Date built Unknown -- mid 1990s?
Gauge 0 gauge
Scale 16mm
Boiler Vertical, single flue with cross tubes
Fittings Safety valve, pressure gauge, throttle, water glass, blower, Goodall valve
Fuel Butane
Blow-off pressure 45 psi
Cylinders Two, double-acting oscillators
Reversing gear Rotary valve
Lubricator Displacement
Weight 3 pounds, 0 ounces
Dimensions Length over end beams, 7-1/2"; width, 2-5/8"; height, 6-1/8"
This tiny locomotive has a lot stuffed into a small space. The boiler is fully fitted. Note the curved frames, distinctive of de Winton locomotives. Construction is neat and workmanlike. Because of its openness, access to controls is a dream.
Atop the boiler, on one side, is the safety valve, throttle, and pressure gauge. The stack is removable, slipping off with a tug.
On the other side is the Goodall valve, the blower valve (left) and the displacement lubricator. The water glass can be seen at the right. Attractive brass bands hold the wood lagging in place.
Left: The gas-control valve is at one end of the locomotive.

Right: The gas filler valve is concealed by a pop-off brass cap on top of the tank at the other end.
Above: The delightful, working, reversing lever in its quadrant. Right: The burner (removed from the engine) is a tiny unit of the same sort that lives inside single flue, horizontal boilers. Here it is housed inside a copper pipe cap.
The rotary reversing valve is conveniently mounted to the cylinders' port block. Below it, the two, double-acting oscillators are kept in place with an external spring.
The underside of the locomotive. At the left can be seen the square bottom of the gas tank. To the right of it is the drive gear on the axle. The burner in the center is surrounded by a screen firebox. At the top of the circular firebox you can just make out the blower pipe entering the firebox. From there it goes up the flue to provide draft.
The fan in place on the stack in an abortive attempt to raise steam.
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