I-B. Cranes

Cranes are used to move materials over variable paths within a restricted area. The major types of cranes are:

General characteristics of cranes:

• Used to move loads over variable (horizontal and vertical) paths within a restricted area
• Used when there is insufficient (or intermittent) flow volume such that the use of a conveyor cannot be justified
• Provide more flexibility in movement than conveyors
• Provide less flexibility in movement than industrial trucks
• Loads handled are more varied with respect to their shape and weight than those handled by a conveyor
• Most cranes utilize hoists for vertical movement, although manipulators can be used if precise positioning of the load is required

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1. Jib Crane

Operates like an arm in a work area, where it can function as a manipulator for positioning tasks

A hoist is attached to the arm for lifting

Arm mounted on the wall or attached to a floor mounted support

Arm can rotate 360°

The hoist can move along the arm

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2. Bridge Crane

Bridge mounted on tracks that are located on opposite walls of the facility

Enables three-dimensional handling

Top riding (heavier loads) or underhung (more versatile) versions of the crane

Underhung crane can transfer loads and interface with other MHS (e.g., monorail systems)

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3. Gantry Crane

Single leg, double leg, and mobile types of gantry cranes

Similar to a bridge crane except that it is floor supported at one or both ends instead of overhead (wall) supported

Used to span a smaller portion of the work area as compared to a bridge crane

The supports can be fixed in position or they can travel on runways

Can be used outdoors when "floor" supported at both ends

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4. Stacker Crane

Similar to a bridge crane except that, instead of a hoist, it uses a mast with forks or a platform to handle unit loads

Considered "fork trucks on a rail"

Used for storing and retrieving unit loads in storage racks, especially in high-rise applications in which the racks are more than 50 feet high

Can be controlled remotely or by an operator in a cab on the mast

Can be rack supported

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Last modified: September 30, 1999