My machine/machinery challenge arises only from my having a few images of what I considered machines are, and the reflection that I had never seen a challenge on these terms. I am not an expert, or even an enthusiast, neither do I have a great collection of stunning machine images, but I know a lot of hoggers do.

Checking the web for definitions, I first found that there are just 6 machines – "Six types of simple machines are Lever, Pulley, Inclined plane, Wedge, Screw, Wheel, and Axle". That turned out to be a pre-industrial revolution approach. Other definitions appear more appropriate to modern times: “a combination of parts that transmit forces, motion, and energy to do some desired work. a sewing machine. : an instrument (as a lever or pulley) designed to transmit or change slightly the application of power, force, or motion. : an organized group that controls a political party.” That last might be extended to include unorganised groups, even disorganised groups!

“A machine is a physical system using power to apply forces and control movement to perform an action. . . artificial devices, such as those employing engines or motors, but also to natural biological macromolecules, such as molecular machines. Machines can be driven by animals and people, by natural forces such as wind and water, and by chemical, thermal, or electrical power, and include a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement. They can also include computers and sensors that monitor performance and plan movement, often called mechanical systems.”

I dared ask the difference between a machine and an engine: “A machine consumes energy whereas an engine produces energy. Engine converts heat energy to Mechanical Energy but machine converts all forms of energy to mechanical energy except heat energy. A engine runs a machine, without an engine a machine can't run.”

Enough of that! Let’s see what you clever photographers come up with.