Pielstick PC Series heavy-duty, four-cycle engines are among the most widely used marine diesels in world shipping service. A total of almost 3,000 have been built by all licensees; of this total, almost 2,400 engines have been for marine service.
Fairbanks Morse Engine Division, Colt Industries, has been the U.S. licensee for the PC-2 Series since 1970 and during that time has sold 124 of these engines, of which 56 were for marine service. In addition, the PC-4 Series is now being offered for marine applications.
PC2.5 engines have a rated speed of 520 rpm and are available in 12-, 14-, 16-, and 18-cylinder configurations. Maximum continuous output is 7,800, 9,100, 10,400, and 11,700 bhp, respectively. Bore is 400 mm, stroke is 460 mm, and displacement per cylinder is 3,528.3 cubic inches. Compression ratio is 11.5:1, and bmep is 280.6 psig.
The engine frame is a welded fabrication, providing maximum structural capability with minimum weight. Individual cylinders are replaceable. Individual water jackets prevent any contact and corrosion between the jacket cooling water and the fabricated crankcase. Caged exhaust valves can be removed and serviced without disturbing the cylinder head. The PC2.5 engines have low fuel consumption over a wide output range, and the ability to burn heavy fuel having high vanadium content. More than 50 percent of the engines in operation run on residual fuels.
Early in 1973, SEMT (Societe d'Etudes de Machines Thermiques) presented to its licensees its latest development — a new four-cycle, heavy-duty engine — the PC-4. This engine was conceived with the dominant thought of 100,000-bhp marine power plants with the economy and practical features of the medium-speed engine. To accomplish this goal, design engineers had to focus on a substantial increase in power per cylinder, low specific weight per horsepower, minimum operating costs, and extended time between overhauls.
Thus, the PC-4 was born. The bore and stroke were increased to 570 mm and 620 mm, which extended the horsepower range to 1,500 horsepower per cylinder. The configuration of the engine is a Vee design with 10, 12, 14, 16, or 18 cylinders. Whereas the PC-2 has an operating speed of 520 rpm, the PC-4 operates at 400 rpm.
In general, the structure of the PC-4 engine is similar in appearance to the PC-2 Series. It has a monobloc frame made of cast steel components and steel plates welded together. It has an underslung crankshaft, with each bearing cap being fixed through two vertical tie-bolts. Individual cylinders, including water jacket, liner, and head are tightened on the frame through eight long studs. The inlet manifolds are located outside the engine, and the exhaust manifold inside the Vee. Lateral camshafts are located in the frame.
With the PC-4 it is feasible to supply up to 54,000 bhp with two engines, which approximates the maximum power that can be absorbed by one propeller. A 100,000-bhp marine propulsion system is possible with four engines on two propeller shafts. Four engines can be set side by side in a ship's hull through a new design configuration. This design also allows far-aft placement of propelling machinery and permits maximum use of space for cargo. PC-4s are available as reversible engines, with full power output in reverse, and can be equipped for automatic operation.
During the past year, Colt-Pielstick activity has been highlighted by the U.S. Navy LSD-41 application and the three Catugs built by Avondale for subsidiaries of Occidental Petroleum.