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October 2000

Archangel's Sgt. Murphy

by Marc Horovitz

History
In 1968, small-scale steam in the garden didn't enjoy much by way of commercial suppliers. But in that year, Stewart Browne of Archangel Models (then of High Wycombe, England), began producing his line of engines. His first was a 16mm-scale model of a Vale of Rheidol Railway 2-4-0.

Stewart Browne went on to develop an engine that was to embody the steam locomotive at its most basic. This locomotive, known as Brick (it was loosely modeled after a brickworks engine) featured a pot boiler, one double-acting cylinder between the frames, a throttle (regulator), and little else by way of amenities. But Brick had one sterling quality. It ran exceedingly well and was both controllable and powerful. It was simple to run and could be turned loose in the garden without fear of mishap. It became, to my mind anyway, the quintessential garden-railway steam locomotive.

Archangel's engines ran well, but success was doubly assured when people like Jack Wheldon and D.G. Rowlands took notice and began to write in the mainstream British model press about the company's remarkable locomotives.

Over the years, Stewart Browne, working mostly alone, produced both an astonishing variety and quantity of engines. Each was essentially handmade and it is difficult to find two that are exactly alike. He made engines that ran on alcohol, gas, and coal. Not all of them are easy to run and a few are downright dogs. However, each has its own character and personality, which contributes to its charm and the fun of getting to know it.

Archangel production continues today, although intermittantly, after several lapses in the past. The owner (i.e., the company) is often difficult to track down and the waiting period for a locomotive extends interminably into the future.

Sgt. Murphy
Sgt. Murphy was introduced in the late 1970s. It is modeled after an industrial 0-6-0T, to which it bears a faint resemblance (Stewart Brown freely took liberties with proportions and details). It went on to become a staple at the low end of Archangel's lineup of locomotives. Mechanically, it is similar to the Brick, with a single, double acting, slide-valve cylinder between the frames. It is a pot boiler, running on a three-wick alcohol burner. The fuel tank resides under the footplate of the cab. Side tanks are simply solid slabs of aluminum. The 2"-diameter boiler is 8" long and its entire interior space is devoted to water, giving the engine extraordinary duration. I've heard tales of some of these engines running for as long as an hour before requiring a refill of water (though the fuel needs to be topped up periodically, a matter of a few seconds).

Controls amount to only a throttle, the stem of which protrudes through the back wall of the cab and ends in a small, knurled knob. Since it is difficult to adjust this knob while the loco is in motion, it is common to find these engines with handles soldered to the control knobs by their owners. Reversing is via slip eccentric, so the engine must be pushed in the desired direction of travel to reset the valve.

Sgt. Murphys came in different colors, but green was common. They were always hand lined by the maker. In later years they were offered in different variations, including gas firing; twin, working outside cylinders; and sometimes even Hackworth valve gear. Whistles could also be had, if required. (To see some photos of a 2004 Sgt. Murphy, click here.)

Performance
To get this engine going, the usual lighting-up ritual is followed: oil all round, fill the lubricator, fill the boiler, fill the fuel tank, and light the fire. It takes a while to heat up all that water. When the safety lifts (usually with a razzberry noise, characteristic of Archangel engines), the fuel tank is topped up. Then the throttle can be opened and the engine given a push. The cylinder is large and massive, so it takes some time to warm up enough to prevent condensation. Hydraulic lock is common at this point.

After a little, the engine shows signs of life. Then, all of a sudden, it wants to go. You might think that a locomotive with only one cylinder that directly drives the axle would be temperamental. Not so. The Sgt., once under way, is surprisingly docile. It will run light at slow speeds, but is powerful enough to easily pull 20-30 axles. When running at slowest speed, there is a definite lurch to its gait, this being from the two powerful piston strokes per revolution of the wheels.

Archangel engines get HOT, and it's not unknown for the overflow pipe on the fuel tank to catch fire on warm days. The overflow is near one of the the plastic buffers and it is easy to burn these up. (The plastic buffers allow you to lift a hot engine from the track without scorching your hands.) It's always a good idea to keep a squirt bottle filled with water handy.

And who was Sgt. Murphy? A famous racehorse!

Thanks to Mike Dockery for filling in some of the gaps in this article.

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Specifications
Builder Archangel Models (England)
Date built 1970s
Gauge 32mm
Scale 16mm
Boiler Pot boiler
Fittings Safety valve, blowdown
Fuel Alcohol
Working pressure 40 psi
Cylinders One, double acting between the frames (dummy outside cylinders)
Reversing gear Slip eccentric
Duration Up to 45 minutes (with refueling)
Minimum radius 3'
Dimensions Length over end beams, 10-7/8"; width, 3-3/8"; height, 6-3/8"
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Left: The loco is spartan in appearance. The smokebox door is a dummy. Side tanks are solid slabs of aluminum, while the buffers are plastic so that a hot engine can be handled.
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Above: The throttle (the engine's only control) protrudes through the back wall of the cab. As supplied, you have only a knurled knob to grasp, so many owners soldered a small handle to it, like this one, to improve controllability.

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Left: The burner is a simple tank connected to the three wick tubes via a feeder tube. The feeder tube is bent in the middle to avoid the crank axle. The unit locates in the frames and is held in place by a single screw in the footplate of the cab.

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Left: The inside of the cab. The displacement lubricator can just be seen on the footplate in the far door of the cab. The fitting on the backhead next to the throttle is a blowdown, useful for emptying the boiler of steam at the end of a run and preventing the resulting vacuum from drawing steam oil from the lubricator back into the boiler.

Right: The belly of the beast. The cylinder is the large, brass rectangle at the top, between the frames. The valve sits atop it. (The cylinders on the outside are dummies.) The main rod (left) drives a crank axle. Both the main rod and the eccentric rod are bent to keep them out of the way of the burner's wicks. When everything is in place,the space between the frames is crowded.

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