Chapter Twenty One - MaK (Caterpillar Marine Power Systems)

Abstract

The German designer and enginebuilder MaK, formerly a member of the Krupp group, came under the umbrella of Caterpillar Inc. in 1997 as MaK Motoren, adding a valuable medium-speed portfolio to the US-based high-speed engine specialist's program. At the time of the takeover, the MaK range embraced five designs with bore sizes from 200 mm to 580 mm offering outputs up to 10 000 kW: the “new generation” M20, M25, and M32 and the longer-established M552C and M601C models. V-cylinder versions of this 430 mm bore design were launched in 2002, extending the power range of the MaK portfolio to 16 000 kW. The new generation of long-stroke medium-speed engines was headed in 1992 by the 200 mm bore/300 mm stroke M20 design for small ship propulsion and genset drive duties. A power range from 1020 kW to 1710 kW at 900/1000 rev/min is covered by six-, eight- and nine-cylinder models. The M20 was joined in 1994 by the 320 mm bore/480 mm stroke M32 (detailed from p. 551). The power gap between the M20 and M32 models was bridged in 1996 by a 255 mm bore/400 mm stroke M25 derivative, which covers an output band from 1800 kW to 2700 kW with six-, eight- and nine-cylinder models running at 720/750 rev/min. All three engines shared common development goals: robustness, high reliability, low overall operating costs, simple maintenance and extended intervals between overhauls. Operational reliability was sought by avoiding corrosion, reducing mechanical wear and tear, increasing component strengths, and reducing the number of interfaces. Low operating costs were addressed by low fuel and lube oil consumptions, and low-grade heavy fuel-burning capability. The in-line six-, eight- and nine-cylinder M32 models have a 480 mm stroke and originally yielded an output of 440 kW/cylinder at 600 rev/min, covering an output band from 2400 kW to 3960 kW at the economic continuous rating (ECR).