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NOHAB and Polar Marine Diesel Engines

NOHAB (Nydqvist & Holm AB) of Trollhättan, Sweden, was a major industrial firm from 1847 through bankruptcy in 1979. NOHAB’s marine diesel engine business — branded Polar — descended from AB Atlas Diesel’s pre-WWI marine engine programme that had begun with the world’s first reversible marine diesel in 1908. NOHAB acquired Atlas’s marine engine works in 1948, consolidating Polar production at Trollhättan. The Polar two-stroke and four-stroke medium-speed engines were licensed to British Polar Engines (Glasgow) from 1928 onwards, creating a parallel UK production line that survives today as the service custodian for Polar engines globally. NOHAB’s diesel operations were sold to Wartsila in 1978-1984, becoming Wartsila Nohab; British Polar Engines remained independent in Glasgow. This article covers the NOHAB/Polar lineage. Visit the home page or browse the calculator catalogue for related propulsion engineering tools.

Contents

Background

NOHAB and the Polar marine engine line illustrate two distinctive features of Swedish industrial history: deep specialisation in mechanical engineering combined with strong international licensing relationships. From the 1847 founding to the 1979 bankruptcy, NOHAB was a multi-product industrial firm — locomotives, marine diesels, hydraulic turbines, industrial machinery — with the Polar marine diesel line as one important segment.

The Polar lineage is interesting because:

  1. Polar engines pioneered marine diesel reversibility through Jonas Hesselman’s 1908 design at AB Diesel (which became part of Atlas, then NOHAB)
  2. British Polar Engines (Glasgow) has held the UK licence since 1928 and survives today as the service custodian for the global Polar fleet
  3. The 1978-1984 Wartsila absorption was part of broader European medium-speed marine engine consolidation alongside Stork-Werkspoor, GMT, and others

This article covers the NOHAB and Polar history.

Founding (1847)

Trollhättan founders

The original company was founded in 1847 in Trollhättan, Sweden, as Trollhättans Mekaniska Verkstad (“Trollhättan Mechanical Works”). The three founders were:

  • Antenor Nydqvist
  • Johan Magnus Lidström
  • Carl Olof Holm

Trollhättan’s location, on the Göta älv river with hydroelectric potential, was strategic for industrial development. The firm initially focused on hydraulic turbines — water-powered industrial equipment that suited the river-rich Swedish geography.

1865: First locomotive

In 1865 the firm built its first steam locomotive, marking the start of a major NOHAB business line that would continue for over a century. By 1912 NOHAB had built its 1,000th locomotive — making it one of Europe’s significant locomotive manufacturers.

1916: NOHAB reorganisation

In 1916 the firm was reorganised as a limited company NOHAB (Nydqvist & Holm AB) — the name acronym preserving the founders’ names (Nydqvist and Holm; Lidström had departed earlier). This reorganisation positioned NOHAB for the substantial 20th-century industrial role it would play.

Atlas Diesel marine engine programme (pre-1948)

AB Diesels Motorer (1898)

Separately from NOHAB, the Wallenberg family had founded AB Diesels Motorer in 1898 — only two years after Rudolf Diesel patented his engine. This Swedish firm acquired licence rights and built early Diesel engines for industrial and marine use.

1908: First reversible marine Polar diesel

In 1908 AB Diesels Motorer delivered the first commercial reversible marine “Polar” diesel engine, designed by Jonas Hesselman. The Polar 1908 engine was one of the first two reversible marine diesels worldwide, and is credited with being the first Swedish-designed marine diesel.

Reversibility was the critical engineering challenge for marine diesel adoption — ships had to operate astern as well as ahead. AB Diesels Motorer’s solution involved a mechanical camshaft shift mechanism similar to other early marine diesel approaches.

1917: Atlas Diesel formation

In 1917 Nya Atlas (formed from earlier Atlas industrial activities) merged with AB Diesels Motorer to form AB Atlas Diesel. The combined entity continued producing diesel engines including the Polar marine line.

Atlas Diesel marine works

Through the 1920s, 1930s, and 1940s, AB Atlas Diesel built marine Polar engines at the Sickla works (Stockholm). The Polar engines covered:

  • Small to medium marine applications
  • Stationary power generation
  • Some specialty industrial uses

1948: NOHAB acquires Atlas marine

The acquisition

In 1948 NOHAB acquired Atlas Diesel’s marine engine works (Sickla, Stockholm), transferring Polar marine engine production capability to NOHAB. The acquisition expanded NOHAB into marine medium-speed diesel engines, complementing its existing locomotive and hydraulic turbine work.

Production was progressively centralised at NOHAB’s Trollhättan facilities. The Atlas Sickla works wound down its marine activity over subsequent years.

Atlas → Atlas Copco

The remainder of Atlas Diesel (compressors and other industrial equipment) became Atlas Copco in 1956 — today one of the world’s leading compressor manufacturers. Atlas Copco’s marine engine ancestry is largely forgotten but historically significant.

NOHAB Polar engine line

Two-stroke marine engines

NOHAB Polar two-stroke engines after the 1948 Atlas acquisition included various medium-bore designs:

  • Bore range: typically 250-400 mm
  • Port-scavenged (loop or cross scavenging in early variants)
  • Direct injection
  • Constant-pressure or pulse turbocharging in later variants
  • Power: ~500-3,000 kW per engine
  • Application: medium-sized cargo ships, fishing vessels, tugs, naval auxiliaries

Four-stroke marine engines

NOHAB also produced Polar four-stroke medium-speed engines:

  • Bore: 250-400 mm
  • Speeds 500-720 rpm
  • Power: ~500-2,500 kW
  • Application: gensets, smaller propulsion, coastal vessels

Locomotive diesel work

In addition to marine engines, NOHAB held an EMD (Electro-Motive Division, GM) licence to build EMD-derived diesel locomotive engines from the 1950s onwards. NOHAB-built locomotives equipped with EMD diesels served Swedish, Danish, Norwegian, and other European railways.

The locomotive business was a major NOHAB activity through the 1960s and 1970s, complementing marine diesel work.

British Polar Engines (Glasgow)

1928 licence

In 1928 the Polar marine engine line was licensed to a British firm in Glasgow, Scotland. British Polar Engines (BPE) was established to build Polar engines under licence for the UK market and Commonwealth/export customers.

The licensing relationship reflected the international scope of marine diesel engine manufacturing in the inter-war period. Major OEMs licensed their designs to multiple national manufacturers, providing local production capability while extending design reach.

Production

British Polar Engines built airless-injection two-stroke crosshead designs under the Polar licence. BPE engines equipped:

  • UK Royal Navy auxiliary vessels and patrol craft
  • British merchant marine ships
  • Commonwealth navies (some applications)
  • Export customers in various markets

Survival as service custodian

After NOHAB’s 1979 bankruptcy and subsequent Wartsila absorption, the British Polar Engines site in Glasgow continued operating independently. BPE has positioned itself as the service custodian for Polar engines globally, supplying spares and overhauls for engines built by:

  • AB Atlas Diesel (1908-1948)
  • NOHAB (1948-1978)
  • BPE itself (1928-)
  • Wartsila Nohab (1978+)

BPE remains a going concern as of recent reporting, with its website (https://britishpolarengines.com/) listing service offerings for E, I, M, N, T-range Polar engines and various ex-NOHAB and Wartsila variants.

1978-1984: Wartsila acquisition

1978: Wartsila takes 51%

In 1978 Wartsila acquired 51% of NOHAB’s diesel operations from parent Bofors. The majority acquisition gave Wartsila operational control of NOHAB’s marine diesel and locomotive diesel businesses.

The 1978 timing reflected Wartsila’s broader European expansion strategy through the late 1970s and 1980s. Wartsila was building its medium-speed marine engine business through acquisitions of struggling European builders.

1979: NOHAB bankruptcy

Despite Wartsila’s majority stake, NOHAB declared bankruptcy in 1979 after the final Rc-class locomotive order. The bankruptcy reflected the broader Swedish industrial contraction of the late 1970s and difficulties in NOHAB’s locomotive business specifically.

1984: Wartsila full acquisition

In 1984 Wartsila acquired the remaining 49% of NOHAB, completing 100% ownership. The combined entity was renamed Wartsila Nohab and continued operations at Trollhättan under Wartsila branding.

Continued operations

Wartsila Nohab continued building marine and stationary diesels at Trollhättan through the 1980s, 1990s, and into the 2000s. The Trollhättan site remains a Wartsila facility today, though product mix has evolved.

Engineering distinctives

Hesselman 1908 design

Jonas Hesselman’s 1908 reversible marine diesel design — built by AB Diesels Motorer (Polar’s earliest predecessor) — is credited as one of the first practical reversible marine diesel mechanisms in series production. Hesselman led construction at Diesels Motorer 1901-1916 and was a major figure in early marine diesel engineering.

Polar two-stroke architecture

The Polar two-stroke marine engines were medium-bore, port-scavenged, single-piston designs. A. Ekelund’s 1960 paper documents the Polar series’ development at NOHAB Trollhättan, providing engineering documentation that remains useful for service technicians today.

Airless solid injection

Polar engines used airless solid injection — pumping fuel directly to the injector at high pressure, no compressed air assist. This was Hesselman’s contribution and represented a significant simplification over earlier compressed-air injection systems.

Legacy

Operational engines

Polar-branded engines remain in service worldwide, though the installed base is contracting as ships are scrapped. Maintenance support flows primarily through British Polar Engines (Glasgow) for legacy spares and overhauls, with some support from Wartsila for engines built during the Wartsila Nohab era.

Industrial heritage

The Trollhättan site has substantial Swedish industrial heritage value. NOHAB-built locomotives are preserved across Northern Europe; some are operated as historical equipment. The Polar marine engine work is less publicly visible but historically important.

Engineering influence

Hesselman’s reversible marine diesel and airless injection contributions influenced subsequent marine diesel engineering. The Polar design philosophy of robust medium-bore engines for general marine duty influenced the broader medium-speed marine engine industry.

See also

References