side lever engine

side lever engine, a development of the Watt beam engine and used for driving the paddle wheels of early paddle steamers. Unlike the American walking beam engine, the beam, which was driven by the steam cylinder at one end and connected with the paddle wheel at the other, was entirely within the ship. There were actually two beams, or levers, and these were placed low down at the sides of the engine. This low positioning was essential in order to allow the use of a long connecting rod attached to the paddle-wheel crankshaft. A long connecting rod was essential in order to minimize the side thrust which would act on the crankshaft if a short connecting rod was used. The steam cylinder was located at one end of the engine and the connection with the paddle shaft at the other end. The piston rod connected with the two side levers by means of a crosshead and two connecting rods. The opposite ends of the side levers were joined by a pin and this drove the paddle shaft with a connecting rod. The condenser was located at the base of the engine; this was normally of the jet type although some engines were fitted with early tubular condensers. The side levers operated the air pump which removed water and air from the condenser, and discharged them into the hot well, the water from the hot well then being pumped back into the boiler.

See also steam propulsion.

Denis Griffiths