Sisu K-Series History

After wartime production of utility vehicles, Sisu restarted civilian lorry manufacturing with the K-23 in 1949 — a conventional-cab truck that established the postwar K-series family. The range grew steadily through the 1950s and 1960s with models including the K-36 heavy dumper, the K-32, and the K-44 with its distinctively Scandinavian 4×4+2 'tri-drive' layout suited to soft Finnish terrain.

Sisu organised the K-series into distinct sub-brands to communicate payload class: Jyry-Sisu ('Thunder Sisu') denoted heavy haulage models, Kontio-Sisu ('Bear Sisu') the medium range, and Nalle-Sisu ('Teddy Bear Sisu') the lighter city-delivery KB-24. A landmark came in 1961 with the K-50SS ballast tractor — at the time reportedly the largest automobile ever built in the Nordic countries.

The K-series also pioneered European cab engineering: the KB-112 of 1962 was claimed to be the first serially produced European lorry with a hydraulically tiltable cab, a feature that became industry standard. Production of the K-family continued until the M-series replaced it in 1970.