What human-powered vehicle did Leonardo da Vinci design with armor and internal hand cranks?

Leonardo da Vinci designed an armored vehicle powered by internal hand cranks.

The machine appears in a drawing from about 1487 and is commonly described as an early tank concept. Its conical protective shell was intended to deflect incoming projectiles, while several crew members inside would turn cranks connected to the wheels. The vehicle also included openings for weapons.

The design is sometimes called a tank, but that modern label can be misleading. Leonardo was not designing a tracked vehicle with an engine, turret, or modern armor. The machine would have been a slow, wheeled fighting platform, and its practical military value is uncertain.

One famous drawing contains a gearing problem that would prevent the vehicle from moving if built exactly as shown. Historians debate whether that mismatch was deliberate concealment or simply an error in the surviving plan. The concept remains important because it combined protection, mobility, and offensive firepower centuries before modern tanks.