Liebherr Overhead Cranes

The Liebherr Group is a German corporation that manufactures a wide variety of equipment including quite a few cranes. Liebherr makes construction cranes, maritime cranes, shipboard cranes, construction cranes, mobile cranes, mobile construction cranes and port equipment. Some of this equipment includes Liebherr overhead cranes.

Liebherr overhead cranes for industrial uses come in all shapes and sizes. Most of Liebherr’s cranes are self propelled so they can be used indoors and out doors. Port and cargo handling cranes are a specialty of Liebherr’s.

Liebherr Cargo Handling Cranes

The Reachstacker is a small but very powerful wheeled crane with an extendable jib that is ideal for stacking cargo containers. A special mechanism on the end of the jib allows the Reachstacker to actually pick up and stack cargo containers the way a child stacks blocks.

The Reachstacker can actually stack cargo containers up to six high yet it is quite small. The Reachstacker is small enough to be used on a ship or inside a warehouse but it can also be used outside in the yard as well. The Reachstacker is one of the smallest and most versatile cargo handling solutions available.

One of Liebherr’s specialties is cranes designed to move cargo containers from ship to port and back again. Liebherr overhead cranes designed for moving containers include rubber wheeled gantry cranes.

Liebherr’s rubber tired gantry cranes are mobile gantry self propelled gantry cranes that can stack several containers at once. These are ideal for moving containers around in a yard or loading them onto railcars or trucks.

A larger solution intended for moving a much higher volume of cargo containers is rail mounted stacking cranes. These Liebherr overhead cranes are designed to move containers from one side of the yard to another. They would be ideal for loading a train or ship or stacking containers for storage.

Ship to shore container cranes are Liebherr overhead cranes specifically designed for loading and unloading ships. These cranes enable crews to stack containers right on the ship for easy transport.

Electric Excavators

A specialized crane manufactured by the Liebherr group is the electric excavator. This is a smaller crane that looks like the excavators and cranes used in construction and similar work. The difference is that it sits in one place and it is electrically powered.

Electric excavators are used for lifting odd sized materials such as scrap metal or garbage. They are often equipped with grapplers or magnets to increase their lifting capacity.

Mobile Harbor Cranes

Another specialty of Liebherr’s is mobile harbor cranes. These are large mobile cranes intended to move around a port facility on their own power. These cranes can lift cargo containers and other large objects on and off of ships. They are also often used for moving bulk cargos.

Liebherr overhead cranes include a number of cranes specifically designed for use on shipboard. These include materials handling cranes, cranes for moving cargo containers and hose handling cranes. Liebherr also manufacturers gantry cranes specifically designed to move cargo containers on shipboard.

Design Guide for Overhead Crane

The basic design for an overhead crane is pretty simple, a hoist mechanism is suspended or mounted upon a guide way running between two supports. A design guide for overhead cranes is needed because of all of the features being added to them.

In the United States a wide variety of safety features and mechanisms are mandated on overhead cranes by the Occupational Health and Safety Administration (OSHA). OSHA is the federal agency charged with overseeing workplace safety which includes overhead cranes.

Any overhead crane installed in the United States will have to comply with OSHA regulations and standards. This means that OSHA regulations and standards will have to be part of any design guide for overhead cranes in the United States.

All overhead cranes in the United States also have to pass an OSHA mandated inspection every two years. Cranes that don’t can not be legally operated in the US. This means the design guide should take this inspection into account as well.

Increasing Complexity of Overhead Cranes

The main reason for the design guide for overhead cranes is the increasing complexity of overhead cranes. A wide variety of features and accessories are being added to overhead cranes as more and more uses are found for these useful devices.

The design guide will have to take the use for which the crane is intended into consideration. One of the main considerations is the load capacity or the amount that the crane will be designed to lift. The heavier the load capacity the stronger the hoist and the more substantial the crane support structure that will be needed.

Another consideration is the way in which the crane will be used. Will it be used primarily as a lifting mechanism or a transportation system? If the crane is to be used as a transportation system, it will have to be a traveling crane which will require more engineering.

The degree of automation required will also have to be considered in the design guide for overhead cranes. Completely automated cranes will require more electronic controls and different safety features.

The degree of operator control will have to be considered as well. Will there be one crane operator or several? Some organizations require special training for crane operators, while others let anybody use the crane.

Crane Location

The location of the crane determines the type of crane to be used and the requirements of the design guide for overhead cranes. Cranes that will be used outside will have to be bridge or gantry cranes. Cranes used inside can be monorail and other cranes that can be mounted on the ceiling.

When a crane is to be mounted on the ceiling or directly to a building the load capacity of the building has to be taken into account. The building must be capable of supporting the loads lifted by the crane. The crane must also be able to operate safely without interfering with the work done on the factory floor.

There maybe separate design guides for different types of overhead cranes. Cranes inside buildings can be part of integrated materials handling systems or production process. This requires an entirely different design guide for overhead cranes.

How Do Gantry Cranes Work?

In its simplest form, a gantry crane is a member of the fixed family of cranes, with the other main family being the mobile variant. Similar crane types which are members of the fixed family include the overhead crane, jib crane, loader crane etc. A gantry crane, also called a portal crane is a type of crane that has a vertical support on one end, and moves horizontally at the other end, either on rail tracks or on rubber tyres. Usually, gantry cranes lift large or small objects by the means of a hoist which is fitted in a trolley and allowed to move horizontally across an area over which it picks and drops items. Gantry cranes are found in most port locations around the world, as they are used for lifting heavy objects around ships, which is a major advantage for gantry cranes in the shipping and heavy duty industries.

The major types of gantry cranes in use today include the container gantry crane, rail mounted or Electrical Overhead Travelling (EOT) gantry crane and the workstation gantry crane, mobile gantry crane.

Applications Of The Gantry Crane

As earlier noted, gantry cranes are utilized mainly in heavy industries, with its largest types being found in ship-building and port locations around the world. This is because they are specifically designed for lifting very large and heavy objects. At their prime locations, these objects include containers and ship-engines. Smaller gantry cranes can be found in car workshops and are used for lifting engines and their components in and out of cars. These variants are usually mobile units or free standing gantry cranes.

Power for operation of gantry cranes is usually derived from two main sources via diesel engine power generators and electrical power. The diesel powered generators can be found at the top of the crane and emits Direct Current (DC) while the electrical power source is usually located at the dock. This is also referred to as shore power and emits Alternating Current (AC).

Gantry cranes can be classified either based on their operational capability and size or physical mode of operation. The most advanced of the pack is the automated gantry crane, also referred to as the Stacker. It is usually unmanned and controlled from a remote operations center. This is used when volumes of large loads, especially containers are to be moved between two holding bays, e.g. from ship to train or truck to ship and vice versa. In terms of size, the rail container gantry cranes are the largest available anywhere in the world. Two famous gantry cranes nicknamed Samson and Goliath, built in 1974 and 1969 respectively are one of the largest in the world today. In combination, they have a lifting capacity of over 1,600 tonnes at heights up to 70metres. They currently reside and execute lifting assignments in the largest dry dock in the world at Belfast.

The hoist, that is, load lifter on gantry cranes can either be located in a fixed machinery enclosure or on a trolley. Trolley hoist systems usually run horizontally along rails and can be fitted either on a single beam or on two beams, that is, a mono girder and twin girder respectively. When gantry cranes run on rubber tyres, there is no need for a rail system, thus reducing cost and earth impact.