Warehouse stacker cranes and their technical supervision
Storage stacker cranes
Stacker cranes are machines used for the automated storage of loads. They are the result of the development of handling equipment such as forklift trucks. They are used as means of internal transport and have applications in warehouse operations. The main purpose of owning and using a stacker crane is to form part of the warehouse system.
Stacker crane equipment
The stacker crane is constructed of:
- upper guidance assembly,
- maintenance platform,
- lift truck,
- lifting motor,
- control cabinet,
- driving engine,
Among the technical parameters to look out for in a stacker crane are:
- maximum height of storage level,
- load capacity,
- as large a load as possible, stating that it can be accommodated in the aisles of the warehouse and placed on the rack,
- work rate.
Types of stacker cranes
Among the stacker cranes, the following types are mentioned:
- mobile - moving on rails built into the floor,
- suspended - attached to previously prepared vaults,
- pole-mounted - with a passable pole on which the chiefs are moved,
- frame - with a drive-through gate over which the chiefs are moved.
The chiefs, incorporating a mechanical system, are usually in the form of extending forks, a conveyor or gripper, designed to hold the goods being transported.
Stacker cranes are also classified by taking into account:
- type of control,
- supporting structure,
- type of collection mechanism.
Another division is stacker cranes subdivided by control mode:
- automatic mode,
- semi-automatic mode,
- manual mode.
Functionality of stacker cranes
The stacker cranes, which move between the warehouse racks, serve to store loads on the warehouse racks or retrieve them at the user's convenience.
The stacker cranes have the ability to function autonomously with the help of a microprocessor, enabling work to be carried out by means of a warehouse information system, WMS, which makes it possible to record the distribution of the materials managed in the warehouse. By the way, this system also works as an inventory tool.
Advantages of storage stacker cranes:
- Safety - enabling the stacker cranes reduces the risk of accidents and damage to goods to a minimum, thanks to the fact that the operation is automatic;
- Ability to generate the right amount of energy - the stacker cranes have the ability to reduce energy consumption by having energy regenerators, returning energy to the grid as the load is lowered;
- Space optimisation;
- Easy access to one's loads - the stacker cranes have it all stored. Receiving and releasing pallets takes place within two types of cycle: single (only receiving or releasing loads) or combined (simultaneous receiving and releasing loads);
- Warehouse management system (WMS) - this enables precise, constant, regular stock-taking, which is very good for the correct control of the location of specific pallets and eliminates errors associated with manual management.
Disadvantages of storage stacker cranes:
- High initial costs - the operations of such an automated warehouse are definitely much more expensive at the beginning than a manually operated warehouse;
- The requirement to have conveyors - opting for stacker cranes also implies a requirement to have other transport systems and above all conveyors from which the stacker crane picks up or deposits the loads handled
According to Polish law, as each warehouse stacker crane is a piece of equipment with a (closer) transport application, it requires technical supervision. Therefore, in order to be able to manage stacker cranes legally and to assemble, repair and modernise them, it is necessary to undergo specific UDT training, available only in a professional and qualified training centre, completed by a commission exam.
The Office of Technical Inspection (UDT) is a national legal entity that has been operating for more than 100 years in the field of safety of technical devices, based, inter alia, on the Act of 21 December 2000 and other legal acts. On the territory of Poland there are more than 9 field branches of the UDT and more than 20 offices.
The duties of the UDT include:
- to control compliance with applicable technical supervision regulations and other applicable regulations,
- carrying out technical supervision of technical equipment, as defined by the legislation (for example, fuel vapour recovery equipment or stacker cranes),
- determination of decisions and their official issuing on the basis of applications after technical supervision,
- keeping of technical records,
- activities to motivate people to improve their skills and competences to work with equipment,
- arranging lesson programmes for UDT courses,
- certification of quality systems for technical equipment.
It is interesting to note that storage stacker cranes weighing less than 250 kilograms do not require the necessary notification to the UDT and training completed with a successful examination. Nonetheless, the company is obliged to send people with the necessary qualifications for maintenance and operation.