the boom arm. A rolloader crane is a loader crane mounted on a chassis with wheels. This chassis can ride on the trailer. Because the crane can move on the trailer, it can be a light crane, so the trailer is allowed to transport more goods. Stacker A crane with a forklift type mechanism used in automated (computer-controlled) warehouses (known as an automated storage and retrieval system (AS/RS)). The crane moves on a track in an aisle of the warehouse. The fork can be raised or lowered to any of the levels of a storage rack and can be extended into the rack to store and retrieve the product. The product can in some cases be as large as an automobile. Stacker cranes are often used in the large freezer warehouses of frozen food manufacturers. This automation avoids requiring forklift drivers to work in below-freezing temperatures every day. Block-setting crane A block-setting crane is a form of crane. They were used for installing the large stone blocks used to build breakwaters, moles and stone piers. Efficiency increase of cranes Lifetime of existing cranes made of welded metal structures can often be extended for many years by aftertreatment of welds. During development of cranes, load level (lifting load) can be significantly increased by taking into account the IIW recommendations, leading in most cases to an increase of the permissible lifting load and thus to an efficiency increase. Similar machines The generally accepted definition of a crane is a machine for lifting and moving heavy objects by means of ropes or cables suspended from a movable arm. As such, a lifting machine that does not use cables, or else provides only vertical and not horizontal movement, cannot strictly be called a 'crane'. Types of crane-like lifting machine include: Block and tackle Capstan (nautical) Hoist (device) Winch Windlass Cherry picker More technically advanced types of such lifting machines are often known as "cranes", regardless of the official definition of the term. Special examples Finnieston Crane, a.k.a. the Stobcross Crane – Category A-listed example of a "hammerhead" (cantilever) crane in Glasgow's former docks, built by the William Arrol company. – tall, capacity, built 1926 Taisun – double bridge crane at Yantai, China. – capacity, World Record Holder – tall, span, lift-height Kockums Crane – shipyard crane formerly at Kockums, Sweden. – tall, capacity, since moved to Ulsan, South Korea Samson and Goliath (cranes) –