The Liberty Ship has a triple expansion engine. The High Pressure "HP" cylinder is the forward cylinder, about 26 inches in dia. The Intermediate Cylinder "MP" is about 42  inches dia. and the Low Pressure "LP" cylinder about 70 inches in dia. The engine developes about 2500 horsepower and propelles the ship at a maximum speed of about eleven knots. The engine room is quite roomy compared to other type ships.

The rear of the engine is connected to the propeller shaft. The propeller shaft is a heavy steel tube some 15 inches in diameter that runs some 150 feet from the engine to the propeller. The shaft is separated from the cargo hold by a watertight cover shaft alley, big enough for a man to walk through and inspect the several bearings supporting the shaft. It is required that the oiler inspect these bearings, and the steering engine twice a watch. J.H.

One of the interesting things about the triple expansion engine is that the diameter of each cylinder was designed so that the power coming from each was balanced with the other other two. The incoming pressure to the HP cylinder was 230 PSIG, the MP piston inlet pressure was 75 PSIG and the LP inlet pressure was 15 PSIG. A.B.

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