Stacker Crane

It is a crane which uses a mast; single/twin (for heavy loads) with forks or platform to handle unit loads. It can be considered as "forklifts on a rail".

The crane moves on a track in an aisle of the warehouse.


The fork can be raised or lowered to any level of a storage rack and can be extended into the rack to store or retrieve products on either side of the crane aisle.

It can either be controlled remotely or by operator in a cab on the mast.

Each stacker crane is manufactured with safety precautionary such as an elevator-type free-fall safety device which is enabled in the event of slack in the chain, a rack mounted above the head as well as the screen-guarding on the front of the stacker to ensure that the operator is protected from being struck by any falling parts.

These stacker cranes are mostly used in automated warehouse known as Automated Storage and Retrieval System (AS/RS) and fully operated using electrical system.

Advantages:

• Ability to cater to high-rise applications where the racks are more than 50 feet high. Thus through this high rack heights, extra storage space are made available.
  
• The stacker crane uses proprietary speed controllers and mechanisms to improve performance and speed up the handling of goods.
  
• Additional space freed up through the absence of passageways and working areas normally required for forklift operations. This enables the company to make use of the additional spaces for other intended operation purposes which is beneficial for them.
• Avoid hazardous working-environment for employees.
  
• High cubic capacity utilization rate and throughput efficiency in the automated warehouse.
• There would be an overall low in maintenance and operating costs incurred by the company.
  
• Allows servicing of several aisles by one crane.
  
• Staffs are more productive as waiting time for forklifts to be available is eliminated soon as they are being replaced by stacker cranes.
  
• The company does not necessarily require skilled labour for operating the stacker crane.
  
• The warehouse can be easily expanded by just adding new rack and crane rail to meet with growing needs of the company.
  

http://www.gaffey.com/html/stackcon.html
http://www.answers.com/topic/crane-machine

www.ise.ncsu.edu/kay/mhetax/index.htm
http://www.okamura.co.jp/english/product/material/pallet/