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MaK (Maschinenbau Kiel) Marine Diesel Engines

MaK (Maschinenbau Kiel) is the historical brand for medium-speed marine diesel engines manufactured at Kiel, Germany, since 1948. Caterpillar Inc. acquired MaK’s marine diesel engine division in 1997 from the Krupp Group, renaming the operating entity Caterpillar Motoren GmbH & Co. KG while retaining the MaK trade name. The MaK product family — M20C, M25C, M32C, M32E, M34DF, M43C, M46DF — covered bore sizes from 200 mm to 460 mm and powers from approximately 1 MW to 18 MW per engine. In October 2021 Caterpillar announced the end of MaK medium-speed marine engine production, exiting the medium-speed market entirely while continuing service support for the existing installed base. This article covers MaK history, engine portfolio, Caterpillar’s acquisition, and the 2021 production exit. Visit the home page or browse the calculator catalogue for related propulsion engineering tools.

Contents

Background

MaK is one of several historic European marine engine brands now in legacy/service-only status. Like Doxford, Götaverken, Stork-Werkspoor, GMT, NOHAB, and Polar, MaK was once a competitive medium-speed engine builder that has either been absorbed into a larger competitor or has exited the new-build market. Unlike most of those defunct brands, MaK’s engines remain widely distributed in current service, with Caterpillar continuing service support through its Marine division.

MaK’s commercial trajectory:

  • 1948: founding as Maschinenbau Kiel under Krupp ownership
  • 1990: Krupp restructuring; military vehicles spun off to Rheinmetall
  • 1992: Rail/locomotive division spun off (later became Vossloh)
  • 1997: Caterpillar Inc. acquired the marine diesel engine division from Krupp
  • 1997-2021: continued production as Caterpillar Motoren GmbH & Co. KG, retaining MaK brand
  • October 2021: Caterpillar announced end of MaK medium-speed marine engine production

This article covers the MaK history, engine portfolio, and the strategic significance of the 2021 production exit.

Founding and pre-1997 history

1948: Maschinenbau Kiel

Maschinenbau Kiel GmbH (MaK) was founded in 1948 in Kiel, on Germany’s Baltic Sea coast. The post-war German industrial reconstruction context shaped MaK’s founding: West Germany was rebuilding industrial capability across multiple sectors, and Kiel had historic shipbuilding and engineering expertise.

Initial MaK products included rail locomotives, military vehicles, and marine engines. The company was a typical multi-product German industrial firm of the era.

Krupp ownership

Through subsequent decades MaK was owned by various Krupp Group entities. The Krupp ownership provided MaK with corporate stability and access to Krupp’s broader industrial resources. The Krupp Group itself underwent multiple restructurings during this period, with MaK consistently part of the Krupp portfolio.

Diversified product mix

MaK produced:

  • Marine diesel engines (medium-speed): the focus of this article
  • Locomotives (diesel, mostly for European railways)
  • Military vehicles (armoured personnel carriers, tanks)
  • General industrial machinery

This diversified mix was typical of post-war German industrial firms but became increasingly difficult to manage as each segment required substantial R&D investment.

Krupp restructuring (1990-1997)

1990: Military vehicles spun off

In 1990 Krupp’s restructuring spun off MaK’s military vehicle division to Rheinmetall AG. This sale focused MaK on civilian industrial products.

1992: Rail/locomotive spun off

In 1992 the rail and locomotive manufacturing division was sold to Siemens (later transferred to Vossloh AG). The Krupp Group was progressively divesting MaK’s various businesses to focus the remaining entity on marine diesel engines.

1997: Caterpillar acquires marine diesel

In 1997 Caterpillar Inc. acquired the marine diesel engine division of MaK from the Krupp Group. The transaction completed Krupp’s breakup of MaK as an integrated firm and gave Caterpillar a strong position in the European medium-speed marine engine market.

The acquisition reflected Caterpillar’s broader strategy of expanding from heavy-equipment focus into marine and stationary diesel engines. MaK provided:

  • An established medium-speed engine product line
  • European customer relationships and service network
  • Complementary product to Caterpillar’s smaller bore engines
  • Manufacturing presence in Kiel

Specific transaction details (price, terms) were not publicly disclosed in available records.

Caterpillar Motoren GmbH

Following acquisition, the operating entity was renamed Caterpillar Motoren GmbH & Co. KG, retaining the MaK brand name for engine designations. Engines continued to be marketed as “MaK M-series” or “Cat-MaK” alongside Caterpillar’s other marine engine products.

Engine portfolio (1997-2021)

Through the Caterpillar ownership period, the MaK product family included:

M20C

  • Bore: 200 mm
  • Stroke: 300 mm (approximately)
  • Speed: 900-1,000 rpm
  • Power: 1,020-1,710 kW (6-9 cylinders)
  • Application: smaller propulsion, specialty applications

M25C

  • Bore: 255 mm
  • Stroke: ~400 mm
  • Speed: 720-750 rpm
  • Power: ~2-3 MW
  • Application: mid-size propulsion, gensets

M32C

  • Bore: 320 mm
  • Stroke: 480 mm
  • Speed: 600 rpm
  • Power: up to ~7.5 MW (9-cylinder)
  • Application: main propulsion, larger gensets

M32E

  • Bore: 320 mm
  • Stroke: 460 mm
  • Speed: 720-750 rpm
  • Power: 3,300-4,950 kW (6L-9L)
  • Application: main propulsion, refined M32C variant

M34DF

  • Bore: 340 mm
  • Stroke: 460 mm
  • Speed: 720-750 rpm
  • Power: 3,000-4,500 kW (6M-9M)
  • DF capability: LNG dual-fuel
  • Application: main propulsion for ships requiring LNG capability

M43C

  • Bore: 430 mm
  • Stroke: 610 mm
  • Speed: 500-514 rpm
  • Power: up to ~16,800 kW (16V variant)
  • Application: main propulsion for cruise ships, large OSV, ferries

M46DF

  • Bore: 460 mm
  • Stroke: 610 mm
  • Speed: 500-514 rpm
  • Power: 5,400 kW (6L) up to 18,000 kW (20V)
  • DF capability: LNG dual-fuel
  • Application: main propulsion, large vessels, cruise ships

Applications

MaK engines through the Caterpillar period equipped:

  • Cruise ships: M43C and M46DF for diesel-electric propulsion plants (Mein Schiff, AIDA, others)
  • Ferries: across the bore range, particularly for European ferry operators
  • OSVs: M32 and M43 for Norwegian and other OSV operators
  • Tugs: M20 and M32 for various tug operators
  • Specialty vessels: dredgers, fishing, research, coast guard

The customer mix was particularly strong in European waters and in specialty applications globally.

October 2021 production exit

Strategic decision

In October 2021 Caterpillar announced the end of MaK medium-speed marine engine production. The decision reflected:

  • Increasing R&D investment requirements for alternative-fuel and emissions compliance
  • Caterpillar’s strategic refocus on smaller-bore high-speed engines (3500 series, C-series) and automation/digital products
  • Competition from Wartsila, MAN, HiMSEN, and others in the medium-speed space
  • Difficult market dynamics for medium-speed marine engines

Continued service support

The 2021 exit was specifically of new-build production. Service support for the existing installed base continues through:

  • Caterpillar Marine organisation worldwide
  • Caterpillar’s spare parts and component supply chains
  • Authorised Cat Marine dealers
  • Continued engineering support for in-service engines

The MaK installed base is large enough to make service support a substantial business for many years.

Industry significance

The 2021 MaK exit was significant for the medium-speed marine engine market:

  • Reduced the number of medium-speed marine engine OEMs by one (Wartsila, MAN, Caterpillar, HiMSEN, Daihatsu, Niigata, ABC, J-ENG remain; MaK departed)
  • Concentrated remaining production further among the surviving OEMs
  • Eliminated the Cat-MaK competitive offering for new-build orders

Strategic context

Cat marine business

Caterpillar’s marine business continues, but focused on:

  • Cat 3500 series (bore 170 × 190 mm): high-speed range up to ~2.7 MW
  • Cat C-series (smaller bores, 100-1500 kW range): high-speed for various commercial and leisure applications
  • Solar Turbines subsidiary: industrial gas turbines
  • Cat Marine integrated solutions: combining engines with controls and ancillary systems

The MaK exit narrows Caterpillar’s marine offering to high-speed engines and gas turbines.

Why exit?

Multiple factors likely contributed to Caterpillar’s MaK exit:

  • Capex requirements for alternative-fuel medium-speed development (LNG, methanol, ammonia)
  • R&D scale required to maintain competitive product line
  • Market position never reaching Wartsila/MAN scale economics
  • Focus reallocation toward higher-margin and less capital-intensive products

Service business value

Despite ending new-build, Caterpillar retains substantial value in MaK:

  • Large installed base requiring continued service
  • Long service life of marine engines (20-30 years)
  • Substantial spare parts revenue stream
  • Service revenue typically higher margin than new-build engine sales

Historical legacy

MaK brand significance

The MaK brand was significant in European medium-speed marine engineering for over 70 years. The brand’s eventual absorption into Caterpillar (1997) and then exit from new-build (2021) represents the broader European retreat from medium-speed marine engine manufacturing.

Other defunct medium-speed brands

MaK joins other defunct or absorbed European medium-speed brands:

The remaining European medium-speed competitors are Wartsila, MAN/Everllence, and the smaller niche players like ABC.

Asian competition

The European retreat reflects intensifying Asian competition. Korean (HiMSEN), Japanese (Niigata, Daihatsu, Mitsui E&S DU), and Chinese (CSSC subsidiaries’ medium-speed offerings) competition has progressively eroded European medium-speed market share.

Service today

For ships powered by MaK / Cat-MaK engines, service flows through:

  • Caterpillar Marine worldwide service network
  • Cat Marine dealer organisations in major maritime regions
  • Caterpillar’s spare parts supply chains for engine components
  • Authorised service contractors for major overhauls

The service network is comprehensive and likely to remain so for decades, given the large installed base.

Future outlook

No new-build production

Caterpillar has not signalled any intention to resume MaK new-build production. The 2021 exit appears permanent.

Service continuity

Service support is committed and likely to remain so. Caterpillar’s broader marine and engine service organisation can absorb MaK service continuity.

Installed-base attrition

Over the next 20-30 years, the MaK installed base will gradually retire as ships are replaced. New ships will use Wartsila, MAN, HiMSEN, or other engines. The MaK installed base will eventually wind down, but very slowly given the long service life of marine engines.

See also

Additional calculators:

Additional related wiki articles:

References