AB Atlas-Polar was a Swedish marine and stationary diesel engine builder formed through the consolidation of several Stockholm-area engineering firms, with the principal lineage tracing to the Atlas Diesel works founded in 1907 and the Polar Diesel works that became the company’s flagship marine product. Atlas-Polar was a significant European marine engine builder through the mid twentieth century, producing two-stroke crosshead diesels for cargo vessels, tankers, and naval auxiliaries. The marine engine business was acquired by Nydqvist & Holm AB (NOHAB) in 1948, becoming the NOHAB-Polar lineage, and was eventually consolidated into Wärtsilä through the late 1980s acquisition of NOHAB by the Finnish group.
Origins of Atlas Diesel
AB Atlas Diesel was founded in 1907 in Stockholm to produce the diesel engine technology that Rudolf Diesel had licensed to several international manufacturers in the early twentieth century. Atlas was the principal Swedish licensee of Diesel’s patents and developed in-house engineering capability for marine and stationary diesel applications. Through the inter-war period Atlas produced large stationary diesel engines for power generation and industrial applications, with marine engines a smaller fraction of output.
Atlas was a major employer in Stockholm and an important Swedish industrial company. Atlas Diesel was eventually acquired by Atlas Copco (the Swedish industrial machinery group), and the diesel engine business was subsequently divested.
Polar Diesel and the marine product line
The Polar marine engine line was Atlas’s principal marine product, a two-stroke crosshead diesel that competed with Burmeister & Wain, Sulzer, and other European marine engine makers through the inter-war and post-war periods. The Polar engines were widely deployed on Swedish-built cargo vessels, tankers, and selected naval auxiliaries, with export markets in Norwegian, German, Dutch, and selected Asian customers.
The Polar two-stroke was a respected product within the marine engineering community, though it never achieved the global market scale of the leading B&W or Sulzer designs. The engine line provided Sweden with sovereign marine engine capability through a period of intense national maritime industry development.
NOHAB acquisition and the NOHAB-Polar era
In 1948 the Polar marine engine business was acquired by Nydqvist & Holm AB (NOHAB), a Swedish engineering company based at Trollhättan. The combined business became known as NOHAB-Polar and continued to produce marine and locomotive diesel engines through the post-war decades.
NOHAB-Polar’s marine product range included the original Polar two-stroke crossheads, progressively updated through the 1950s and 1960s, plus medium-speed four-stroke engines for marine generator sets and smaller propulsion applications. The company also produced significant numbers of locomotive prime movers, with NOHAB-built diesel-electric locomotives operating on Swedish, Danish, Norwegian, and Hungarian railways.
NOHAB-Polar marine engines were particularly notable in:
- Swedish-built tankers and cargo vessels of the 1950s and 1960s.
- Norwegian-built cargo vessels of the same period.
- Selected naval auxiliaries and Coast Guard vessels.
Wärtsilä consolidation
Through the 1980s NOHAB-Polar faced the same intensifying competition that affected the broader European marine engine industry. Sulzer and B&W dominated the slow-speed segment, and the rise of Asian shipbuilding eroded the Scandinavian shipbuilding orderbook on which NOHAB-Polar depended.
In 1986 Wärtsilä (covered in a separate article) acquired NOHAB-Polar, integrating the Trollhättan engineering and manufacturing capability into the Finnish group’s broader marine engine business. Through the late 1980s and 1990s the NOHAB-Polar product range was progressively rationalised, with Wärtsilä’s own medium-speed four-stroke engines (the Vasa 22, Vasa 32, and successors) absorbing most marine main propulsion orders.
The Trollhättan site continued some manufacturing and service activities under Wärtsilä, but the standalone Polar marine engine product line was effectively retired by the late 1990s.
Engineering heritage
The Atlas-Polar lineage was significant for several reasons:
- Independent Swedish marine engine capability maintained through much of the twentieth century, supporting national shipbuilding and shipping industries.
- The Polar two-stroke as a viable European alternative to Burmeister & Wain and Sulzer through the inter-war and post-war periods.
- Continuity into Wärtsilä, where engineering and manufacturing experience contributed to the modern Wärtsilä product range.
The engineering archives are preserved in Swedish archives and within Wärtsilä’s corporate records.