my The Transition between Single and Tandem Container Lifting

As the demand for moving more containers in less time increases, ports and terminals are turning to tandem lift operations to increase their container throughput.  But what should terminals be looking for when choosing a tandem system for their operations? Especially for transhipment terminals that perform many mode changes between single and twin spreaders during busy and complex lifting schedules?

A crucial factor – speed and method of spreader change-over

One of the most important factors when choosing the right tandem headblock system is the speed and the method of transition between spreaders (single to twin spreader or twin to single spreader).  RAM, which has for many years, been at the forefront of innovation, has been providing a tandem headblock system called “SingFlex” that performs spreader change-over at the push of a button, in a record-breaking 46 seconds, when placed in the purpose-built docking station located on the sill beam of the crane.

How does SingFlex help terminal operators?

As the process of switching between single and twin spreaders takes place in the docking station at the touch of a button, no ground staff are required to assist in the transition.  This means the change-over is done quicker and safer, leaving the crane operator the ability to move more boxes per hour, without risk to the safety of ground staff.

Whilst the concept of tandem lifting is the same with other tandem headblock systems, with twin lift spreaders side by side, the method and speed of change-over differ considerably. Some tandem systems need trailer transportation of the second spreader brought to the quayside, others require detachment of headlock and single spreader before re-attaching both spreaders to the headlock. These methods are labour intensive and time-consuming.

SingFlex – quick and simple

Consisting of a primary and secondary headblock, the single spreader on SingFlex is always connected to the primary headblock for a single spreader twin lift operation.  When tandem is needed, the crane operator lowers the single spreader into the docking station located on the sill beam, which contains the secondary headblock connected to the second spreader.

At the push of a button, SingFlex patented sliding mechanism moves and extends the sheaves between the primary and secondary headblock.  Once completed (46 seconds), a signal to the crane operator indicates mode change is complete, and the tandem spreaders can be lifted clear from the docking station.  The system also works in reverse, changing from tandem to single spreader mode in the same record-breaking time.


When speaking to our customers they are often surprised by the flexibility of the headblock system. They note they weren’t aware their crane operator did not have to transition out of tandem (twin spreaders) to lift a single container or to remove a hatch, as it can be done whilst in tandem.


Want to know more? 

The battle between single vs dual hoist cranes for tandem lift operations

We consider the reasons why a single hoist crane and tandem headblock attachment is a more cost-effective investment than a dual hoist crane. 

Read more