Lister 5/1 Diesel

Marine Engines

Doxford - Page 1

William Doxford & Sons (Engineers) Ltd., were one of the stalwarts of British shipbuilding, having a ship repair and construction yard as well as the engine business with which they built a reputation amongst ship owners that was to last over 70 years.

Doxfords built vertical, opposed-piston two-stroke diesel engines for ships, up to 8000 bhp, and their design became a standard unit for British flag-carriers until the licence-built Sulzer and B&W engines challenged their position in the early 1960's. The single-crankshaft engines had connecting rods for both the lower and upper pistons, with two rods for the upper piston. It is completely different to the Junkers opposed-piston design, as the upper pistons are connected to the single crankshaft by connecting rods each side of the main cylinder. Doxford Layout This system had inherent advantages over the standard four-stroke engine, as the two-stroke running enabled a low operating speed (115 rpm), thus eliminating the requirement for a reduction gearbox between the engine and propeller, and as the engine was reversible, no reverse gear was required.

Their works were situated in Sunderland, and they either supplied engines (or they were built under licence) to all the major shipbuilders in the United Kingdom. Overseas they had major licencees like Sun-Doxford in the USA and there were other joint companies in the Middle and Far east.

Doxford Opposed-Piston Main Propulsion Marine Engine
Side Sectional view of engine, showing Cylinder and Connecting Rods


Doxford Opposed-Piston Main Propulsion Marine Engine
End view of engine, showing Cylinder in section


Doxford Opposed-Piston Main Propulsion Marine Engine
View of opposite end.


Doxford Opposed-Piston Main Propulsion Marine Engine
End view showing Scavenging Pump


Doxford single-cylinder demonstration engine



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