JNR B20-3 0-4-0T
a review by Nick Wantiez
Aster Hobby Corporation has recently introduced a beautiful 1/24 scale 0-4-0 shunting locomotive known as the Japanese National Railways, (JNR), B20. Configured in late 1943, when shunting locomotives were desperately needed to support the war effort, the B20 was envisioned to be a simple, low cost, yet rugged design, which was to be produced under time and tooling restraints which most nations would have considered impossible. Undaunted by the difficulty of the assignment, the locomotive design committee set to work and soon developed a viable prototype.
The 0-4-0 B20 had a simple coal fired non-superheated boiler. Its plate
frames supported two conventionally mounted outside cylinders with piston valves
driven by Walschaert valve gear. Side
tanks provide an ample water supply while coal was carried in the rear bunker.
The first B20 went into operation in 1944 - it lived up to all of its
requirements and the design was so successful that production continued into
1947 almost two years after the war’s end.
Aster B20 is a 1/24-scale model of the third production locomotive.
It is a faithful representation of the original and was scaled from the
B20-3, which is currently on display in Japan.
It operates on gauge 1 track and is size compatible with G scale
equipment – I am currently hauling two Bachmann passenger cars fitted with
knuckle couplers, which match up perfectly with the B20’s couplers.
of the Aster B20-3 are as follows:
Gauge: 1 (45 MM)
(1 ¾ in)
Length: 302 MM over couplers
Width: 106 MM
Height: 148 MM
Weight: 2.8 KG
Arrangement: 0-4-0 35 MM drivers
(also called an 0-2-0 Four Wheeler B)
Cylinders: 12 MM bore x 20 MM stroke with Walschaerts Valve
Boiler: Center flue
butane fired 120 cc water capacity 80% full
Pressure: 2 kg/sq cm
(approximately 30 psi)
Fittings: Two safety valves, pressure gauge, water gauge, regulator,
check valve filler plug.
Lubricator: Roscoe displacement type
Radius: 0.55 M
The kit is typical of previous Aster products. Parts are neatly packed and identified. All hardware is provided, as are some special tools, however it will be necessary to have some other tools, such as nut drivers and pliers, at hand to successfully assemble the kit. These are identified in the instructions.
Aster’s Ms. Chihiro Kawasaki, who once lived in the United Kingdom and has excellent English language skills, is responsible for customer service and assuring that the drawings and instructions are satisfactory for English speaking builders. I found them to be clear and easy to understand.
kit went together in about fifteen hours without any difficulties.
There were a few tricky assemblies but the instructions gave sufficient
guidance to make them seem routine. Being
a senior citizen whose eyes have seen better days, I found it necessary to use 1
½ power reading glasses during most of the assembly.
While locomotive building is fun, my first love is operations so even
though the Seattle weather was dark and gloomy at the time, I cleaned off my
track and steamed her up. Photos 1
through 8 show various shots of the B20 - it is a handsome little engine with
the B20 is easy. First the chassis
is oiled with a light machine oil and the lubricator, which is located in the
right hand side tank, is filled with steam cylinder oil.
Next the boiler is filled to 80 % full using 120 CC of distilled water.
I fill through the upper fitting, which is located in the sand dome,
although a check valve fitting is located on the lower left hand side beneath
the cab, which will accommodate a trackside pump.
The butane tank is located in the cab and is filled through the top using a removable fitting which screws into the tank. The burner is easily lit. While photo 5 does not clearly show this, to light the burner one merely opens the smoke box door, inserts a flame source and cracks open the burner valve. The burner quickly lights, the door is closed and the valve adjusted to provide a flame with a “mild” roar. Steam is up in a few minutes.
will be a bit stiff for the first few hours but soon loosens up and runs like a
dream. I have only been able to put a few hours on my locomotive and
have found it to be user friendly and very powerful. You will note in the photos that the cab roof is not in
place. Aster provides hinges for
the roof but I decided to leave it unhinged since it is much easier to refill
the fuel tank and there is less chance of damaging the cab.
When these photos were taken, the cab roof was resting safely on my
is also in the process of designing a butane utility car, which will carry a
large supply of butane and water. The
car will contain a battery driven water pump.
The butane supply will be attached to an existing lower fitting in the
B20’s butane tank. Aster expects
that the new car will be available later on this year. While there are no specific instructions provided, the B20
can be radio controlled if desired.
In summing things up, I found the Aster B20 to be an excellent small-scale locomotive, which is easy to assemble and operate. It is rugged and reliable - much like its full size prototype several of which continued in service as late as 1972. I believe that it will be a good first project for newcomers to the hobby as well as an interesting addition to the collections of experienced builders and I recommend it without qualification.
This article originally appeared in (Vol. 36.
No. 4) (July / August 2002) issue of Live Steam. Appreciation for permission to reproduce it on SouthernSteamTrains.com
is expressed to Nick Wantiez, author, and to Clover McKinley, Editor of Live