This child group gathers mechanical engineering inventions that produce mechanical power or carry it between the parts of a machine, including the steam engine, internal combustion engine, diesel engine, gas and steam turbines, and the crankshafts, pistons, flywheels, gears, clutches, bearings, pulleys, levers, shock absorbers and universal joints that transmit or smooth that power once produced. Their shared work is generating rotational or reciprocating force and moving it through a mechanism, as distinct from the specific machines built to manufacture, farm or move materials with that power.