PC26B design details

Frame: a stiff nodular cast iron crankcase construction.

Cylinders: each cylinder, including a water jacket and bore-cooled liner, is fitted into the crankcase. Only the upper part of the liner is cooled, avoiding any flow of water in the crankcase and hence possibility of corrosion.

Crankshaft: the one-piece forged unit rests on underslung main bearings fitted with thin bearing shells. A temperature sensor is fitted

on each main bearing, preventing the development of shell bearing abnormality.

Connecting rods: the bevel cut big end cap is secured by serrations on the rod. In V-type engines the connecting rods of a cylinder pair are mounted side-by-side on the same crankpin.

Piston: the composite-type piston comprises a steel crown ('shaker' oil cooled) and a light alloy skirt of the stepped boss type to reduce stresses under peak combustion pressure. The floating piston pin permits free rotation. The five-ring pack includes two compression rings while two spring-loaded scraper rings control lube oil consumption, their position in the upper part of the skirt facilitating easier piston and liner lubrication.

Cylinder head: a vermicular cast iron component attached to the water jacket and to the liner by eight tie-bolts anchored in the crankcase bosses.

Valves: both inlet and exhaust valves have a tight guide bush and the exhaust valves feature a turning device. The entire water flow across the cylinder head passes through the exhaust valve cages, substantially decreasing the valve seat temperature.

Fuel injection: the injectors are cooled by a separate freshwater system. The fuel pumps provide a pressure exceeding 1000 bar.

Camshaft: the bearings are secured with four bolts directly below the injection pump supports, an arrangement which avoids the transmission of injection stresses to the crankcase. Each camshaft and its bearings can be removed laterally from the side of the engine. The fuel pump driving gear design secures a low contact pressure between cam and roller.

Turbocharging: a patented modular pulse converter (MPC) system represents a compromise between impulse and constant pressure systems, and also fosters easier maintenance of piping and expansion bellows.

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