- Current models-

Class 31b (NSB)

New 2005

The prototype:

Class 31b is a classic Norwegian mountain locomotive. During many years it was in use on the famous Bergen railway with its long, severe grades and hard climate.

Forerunners to Class 31b were four Class 31a engines, delivered in 1916-1919. These had four high pressure cylinders, but were in all other respects identical with the compound engines of Class 31b. However, the simple expansion engines were considered somewhat inferior to the compounds.

The Class 31b was then delivered during the years 1920-1926 in 23 examples from builders in Norway, Sweden and Italy. Some of the engines were delivered to the Dovre, Gjövik and Sörland lines. When the Bergen line was electrified some engines were transferred to the Hamar district in the beginning of the 1960ies.

Class 31b is one of the most well known and successful Norwegian steam locomotive designs. Its four cylinder compound machinery and four coupled axles give the engines a high and even pulling power in combination with smooth running characteristics. The boiler has an excellent steaming capacity, especially after raising of the working pressure from 13 to 16 kp/cm2. In spite of its smaller boiler Class 31b is considered the equal of the “Great Germans” Class 63b (ex German Class 52 Austerity) and were second only to the “Dovregubben” Class 49 in power.

The last Class 31b engines were in use until the end of the 1960ies. Nr 452 is preserved at the Railway Museum in Hamar.

Some technical data:


Builders Thune, Hamar, Nohab och Breda
Driving wheel diam. 1350 mm
Cylinders 420/630 x 600 mm
Boiler pressure 16,0 kp (originally 13,0)
Grate area 3,0 m2
Permitted speed 70 km/h
Adhesion weight 57,6 tons
Total weight with tender 123,2 tons
Lengths over buffers 18660 mm



The model:

Type 31b is a very useful allround engine in model as well as in full scale. It´s compact and powerful and has a speed register which fits the fairly short running distances on most model railways very well. Our model, which is hand built in brass is produced in no less than seven different versions which represent different examples as running after WW II. The model has its Swiss precision motor placed in the tender. From there the power is transmitted to the engine by means of a cardan shaft and a gear box equipped with ball bearings. The drive is on the third coupled axle from where the power is transmitted to the other coupled axles by the coupling rods. The rods are linked in precisely the same way as on the real locomotive in order to allow upward and downward movement of the sprung axles. The gear ratio is so chosen that the engine runs very smoothly up to the prototypical top scale speed of 70 km/h.

The model is characterized by

  • Exact scale 1:87 (H0)
  • 2-rail DC with current collection through 6 axles
  • Working main headlight in front and back
  • Prepared for digital control system / decoder
  • Simulated outside and inside compound machinery with a forged crank axle
  • Cab with detailed interior
  • Detailed smokebox interior and smokebox door which can be opened
  • Glazed windows
  • Sprung driving wheel axles with ball bearings
  • Wheel tires in stainless steel with RP 25-profile
  • Minimum curve radius 600 mm
  • Sprung couplers and buffers
  • Heavy lead weight in the boiler for high traction
  • NEM coupling holder at the back of the tender
  • Signs and decals with all prototype engine numbers enclosed
  • Realistic running characteristics 0-70 kph
  • Original Brimalm spare parts kept in stock Five year technical warranty.



The model is built in the following versions (25 examples of each version):
Nr 430, “Bergen” version with high mountain tender and no smoke deflectors. Red wheel tires and blue coupling rods.
Nr 430, “Hamar” version with some deflectors as on the photo above and “regular” tender.
Nr 447, Standing smoke deflectors,cylinder dome, “ordinary” tender.
Nr448, Newer version. Standing smoke deflectors, cylinder dome, “ordinary” tender.
Nr448, Older version with big dome, red wheel rims and blue coupling rods.
Nr 451, Standing smoke screens, big dome, special tender top.
Nr 452, Museum version as preserved today.

Please click on “drawings” below to watch drawings of the different versions.

Drawings