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The finished A3.

Andrew MacPherson's A3

by Andrew MacPherson
Southern California

Photos by the author

October, 2010

This loco has a long history of interest to any enthusiast of British gauge-1 railways. It started life as a streamlined Aster A4 in the collection of the renowned English collector Bob Head.

The work to convert it to an A3 was begun by British loco builder David Baker, known to many in the USA through the locos he built for Richard Runyon. This work included converting it into a two-cylinder loco (instead of three) for prolonged and easy running.

The design brief was to make the engine run as strongly as Aster's super-reliable Southern Pacific Daylight. The first thing that was done was to remove the A4's troublesome middle cylinder, which caused most of its running problems. The loco's undercarriage was taken apart and work on the undercarriage was started. Unfortunately, ill health brought the project to a stand still.

Sadly, after a few difficult years Bob Head passed away. His famous collection was auctioned off at Christies in London, which is where I purchased the half-finished project. I then sent the loco back to David Baker to finish the work that he started, but with a slightly different visual brief. By this time Aster had announced its own A3 Pacific design, so I asked David to create an exact replica of No. 4472 as it appeared in its original guise for the World's Fair at Wembley in 1924.

Unfortunately, the loco has never been run. I don't have my own track but I'm hoping it will get it's christening this year on one of our Southern California tracks. I have a lovely seven-car train of J&M Pullmans to go with it.

Builder Aster / David Baker
Date built Period from 1984 to 2005
Gauge 45 mm (gauge 1)
Scale 1:32
Boiler David Baker three-flue design
Fittings Safety valve, pressure gauge, regulator, water glass, blower, check valve
Fuel Alcohol
Blow-off pressure 80 psi
Cylinders Outside twin with D-valves; bore, 12 mm x stroke 20 mm
Reversing gear Walschaerts valve gear with screw reverser
Lubricator Roscoe displacement
Weight Approximately 14 pounds, fully fueled
Dimensions Length, 691 mm (engine, 433 mm; tender, 127 mm); width, 86 mm; height ,127 mm
This LNER A3 Pacific started life as an Aster streamlined A4 with three cylinders.
British builder David Baker finished the model exactly as No. 4472 appeard at the 1924 World's Fair.
The backhead reveals the engines Aster lineage. Visible are the pressure gauge, water glass, regulator, blower, check valve, and, at the far right, the screw reverser.
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