Container crane

In a nutshell

A container crane is a large gantry crane used for loading and unloading container ships. Positioned at the edge of a container terminal quay, it moves containers between the ship and the shore using a spreader. In English, it is known as a ship-to-shore crane, or STS crane for short.

How does a container crane work?

The steel structure of the container crane spans the work area at the quay edge. A waterside boom extends over the moored container ship, along which a trolley moves horizontally between the ship and the terminal.

The hoist lowers the spreader onto the container, where its twistlocks lock into the container's top corner fittings. The container is then lifted, moved horizontally by the trolley, and set down on the shore side or within the ship.

When unloading, the process generally follows this sequence:

  1. Position the spreader on the container and lock it
  2. Lift the container out of the ship
  3. Move the container to the shore side using the trolley
  4. Set the container down on a terminal vehicle or transfer area
  5. Unlock the twistlocks and lift the spreader

When loading, the process runs in reverse.

Why is it called a container bridge?

The name comes from its bridge-like steel structure. The crane spans the quay edge and the landside work area. Its boom extends over the ship, allowing the trolley to move containers between the vessel and the terminal.

The terms container bridge and container crane are often used interchangeably. In a port context, "container bridge" usually refers specifically to the large quay crane used for handling between ship and shore.

What are the components of a container crane?

The essential components include:

  • Gantry and steel support structure
  • waterside boom
  • trolley
  • hoisting gear and hoist ropes
  • spreader with twistlocks
  • gantry travel gear on the quay edge
  • control and safety technology
  • operator cabin or remote control station, depending on the system

Many ship-to-shore cranes can travel along the quay edge. This allows them to be used at different sections of the ship.

What is a spreader?

The spreader is the load-handling device between the ship-to-shore crane and the container. Its twistlocks engage with the top corner castings of the container and lock into place.

Telescopic spreaders can be adjusted to different container lengths. Depending on the design, cranes can also move multiple containers in a single lift. Whether this is possible depends on the ship-to-shore crane, the spreader, the container weights, and the operating conditions.

Which containers can a ship-to-shore crane move?

Ship-to-shore cranes are designed for handling standardized freight containers . Depending on the spreader and crane, this includes, for example, 20-, 40-, and 45-foot containers as well as various container types.

For special containers, oversized cargo, or cargo on flat racks, additional lifting gear and specific work procedures may be required. The permissible load capacity of the ship-to-shore crane and the load-handling device used must not be exceeded.

Where are ship-to-shore cranes used?

Ship-to-shore cranes are located at the berths of sea and inland port terminals. Their primary task is handling cargo between the ship and the landside.

Once set down, other vehicles and cranes take over transport within the terminal. These include, for example:

  • straddle carriers
  • Terminal tractors
  • Automated guided vehicles
  • Reach stackers
  • Rubber-tired or rail-mounted stacking cranes

The container crane itself is therefore only one part of the entire transport chain at the terminal.

Difference between container crane and reach stacker

A container crane is a large crane system located at the quay edge. It moves containers between the ship and the terminal and only travels along its crane runway.

A reach stacker, on the other hand, is a free-moving handling vehicle with a telescopic boom. It transports and stacks containers within a depot, freight yard, or terminal. It is not used for the direct loading and unloading of large container ships.

Difference between container crane and stacking crane

The container crane handles the transfer between the ship and the landside. Stacking cranes, by contrast, organize storage within the container block.

Stacking cranes include, among others:

  • RTG: rubber-tired gantry crane
  • RMG: rail-mounted gantry crane

These machines move containers, for example, between storage rows and terminal vehicles or railway wagons.

How is a container crane operated?

In conventional systems, a crane operator controls the movements from a cabin. Modern container cranes may also feature camera-assisted, remote-controlled, or semi-automated functions.

The level of automation varies from terminal to terminal. Even with automated processes, monitoring, safety systems, and clearly defined operating areas remain necessary.

Frequently asked questions

What is a container crane in simple terms?

A container crane is a large harbor crane that moves containers between a ship and the terminal. It lifts the container using a spreader attached to the top corner fittings.

Is a container crane a gantry crane?

Yes. A container crane has a gantry-style support structure. It is specifically designed for handling containers between a ship and the quay edge.

What does STS crane mean?

STS stands for "Ship to Shore." An STS crane is the standard industry term for a container crane located at the quay edge.

Can a container crane lift multiple containers at once?

Some container cranes and spreaders are designed for twin-lift or other multiple-lift operations. Whether multiple containers can be lifted together depends on the technical equipment, the total weight, and the operating conditions.

How does the container get to the storage area after being unloaded?

The container crane typically places the container onto a terminal vehicle or a transfer area. Further transport to the storage block is then handled by equipment such as terminal tractors, straddle carriers, or automated guided vehicles.