The invention provides a mechanical engine, belonging to the field of mechanical equipment. The mechanical engine is characterized by comprising a primary power generating mechanism, a power transition mechanism and a power release mechanism which are arranged on a stander; the mechanical engine has reasonable structure and simple operation, and can be applied to tool vehicles instead of walk, soas to be convenient and practical as well as have low cost, no pollution and low energy consumption, thus being more beneficial to popularization and application within large scope.