The automatic storage system is defined heavy if the load unit it moves weighs more than 500 kg. The majority of heavyweight automatic storage systems have load units weighing between 1,000 and 1,500 kg, but can accommodate weights of 3,000 kg and over.In this type of storage system the load units are usually wooden pallets or metal cases but special load units are often used, specific for the goods contained, such as the coil cradles. Usually the loads are retrieved by means of telescopic forks that operate in single, double or triple depth. The storage systems for heavy loads are characterised by very sturdy stacker cranes. In the majority of cases translation is performed by means of a pair of metal wheels, at least one of which is motorised. The load unit is lifted by means of chains or steel ropes. The stacker cranes for heavy loads can be provided with operator cab , useful in the case of inspection and maintenance, in particular when operating at a height. Although not at the same level as the storage systems for light loads, these automatic storage systems nevertheless perform well. The translation speed is usually 3 m/s with a lifting speed of 0.6 m/s, often reaching or exceeding 1 m/s.

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