The most difficult engines riddles

A stepper motor is used in devices that need precise positioning and speed control. Because it moves in precise repeatable steps, the stepper motor is used in devices like 3D printers, camera platforms, plotters, scanners, analog quartz watches. etc.

A desmodromic valve is a reciprocating engine poppet valve that is positively closed by a cam and leverage system, rather than by a more conventional spring. The main benefit of the desmodromic system is the prevention of valve float at high RPM. It has been applied to top-of-the-range production Ducati motorcycles since 1968.

The Wankel engine is a type of internal combustion engine using an eccentric rotary design to convert pressure into rotating motion. Wankel began development in the early 1950s at NSU, and completed a working prototype in 1957.

Honda is the largest engine manufacturer in the world. Honda also provides engines for sport cars, although it withdrew from Formula 1 series in 2008.

Since Volvo introduced their Volvo 850 in 1992, much of their lineup has switched to straight-five power, with their engines also seeing use in Fords. Currently, Volvo Cars are using the straight five-cylinder engine of own design in every vehicle in the lineup.

In this engine the pistol has a triangular shape (Reuleaux triangle with a slightly convex edges).