The power stroke extracts work from these gases as they expand and force the piston to BDC. In the exhaust stroke, the exhaust valve is open and the combustion products are expelled from the cylinder.

The patented engine ... stroke internal combustion engine design. It uses a special crankshaft to create extra compression and power strokes per cycle. Nearly all combustion-powered vehicles use a ...

Richard Trevithick’s design had a boiler but this was removed to make the internal combustion engine. The German inventor Nicklaus Otto developed the first four stroke engine in 1876.