Cranes

conveyors-header


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


Cranes

 






1. Jib Crane

  • Horizontal boom (jib) supported from a stationary vertical support
  • Hoist can move along the jib and can be used for lifting
  • Operates like an arm in a work area, where it can function as a manipulator for positioning tasks
  • Jib can also be mounted on the wall
  • Arm can rotate up to 360°



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)



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



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