Having evolved from the early piston and cylinder steam engines used to pump water out of mines, maritime steam engines were developed in the late eighteenth century. Experimentation with various engine types and placements led to the walking beam design.

Called a “walking beam” because of its steady rocking action, the diamond-shaped beam pivots in the center, transmitting the vertical motion of the engines single large piston to the shaft that turns the paddlewheels. The beams and supporting structure were originally constructed of wood and later of iron and steel.

Paddle wheels also varied in design from the fixed paddle wheel to the moveable paddle or feather wheel design. A series of rods and cams in the feather wheel kept the paddles in a vertical position while they were in the water, thereby increasing their efficiency.

Walking beam engines and paddle wheels were eventually replaced in the 1850s by faster, more efficient steam engines developed to turn propellers. However, paddle-wheelers continued to be used into the 1940s on inland waterways.

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