Gravitational conveyors, also known as line-shaft conveyors, are widely used in warehouses to move boxes weighing up to 50kg. These conveyors use freely rotating rollers to allow boxes to move down due to gravity, which explains the name of this solution. Typically, gravitational conveyors are not powered and are run by a shaft below the rollers, making them economical for high-volume, fast-moving applications like modern e-commerce warehouses.