Safe spreader operations are of utmost importance for container terminals. The risks related to damage, loss or fall of a container can lead to serious consequences. Accidental damage to containers and the spreader can also result in damage to the container vessels, with a subsequent delay in the sailing schedule. To help our customers avoid these risks Bromma offers to equip spreaders with TTDS – Twin-Twenty Detection System. 

TTDS  assists the crane operator in detecting a dangerous situation of two 20-foot containers under a spreader positioned to lift one 40-foot container. The system is designed to detect the gap between two 20-foot containers situated next to each other.

The TTDS is only active when the spreader is in the 40-foot position. The TTDS checks for a gap, i.e. if it is two 20-foot containers.  When a gap is detected, TTDS sends a signal to spreader’s PLC, which activates interlocking action and prohibits locking onto two twenty-foot containers when the spreader is in single-mode and in 40-foot position. 

Bromma’s TTDS technology revolves around seven photoelectric sensors. Five sensors are used to detect a gap. Two sensors are used to detect the existence of the containers. 

There are several benefits, which you can expect when choosing to add the Bromma TTDS to your spreader specifications: 

  • Reduced amount of false twin-twenty indications Many twin-twenty detection systems have a limited number of sensors and are restricted in differentiating between potential accidental twin-twenty situations compared to situations without risks. The Bromma twin-twenty detection system is designed to better differentiate between such situations and thereby reducing the amount of false twin-twenty indications that need to be bypassed, implying a more reliable and productive system.
  • Easy Mounting. The Bromma TTDS can be mounted anywhere along the centre of the spreader. It is recommended that the TTDS be mounted inside the mainframe for maximum protection. All Bromma spreaders are prepared with a mounting plate for the TTDS inside the main frame.
  • Ability to detect an unsafe twin-twenty lift even without a gap. The Bromma TTDS can detect an unsafe twin-twenty lift even if the containers are butted together and there is no gap. The algorithm is based on the fact that an unsafe twin-twenty lift will lift the ends of the containers that are locked onto the spreader and the ends at the center will not be lifted. 
  • Reliable even if one of the gap sensors fails. The TTDS design prevents the failure of a sensor from causing the system to also fail and send a ”go” signal during a twin-twenty condition. Since the definition of a gap is two or more sensors, the system will not shut down if one of the gap sensors fails. The system will become more sensitive to a twin-twenty condition.
  • Detecting overheight frame. The Bromma overheight frame OSR45 can be equipped with the optional TTDS plate, on top of the OSR45, helping the TTDS to detect empty spaces during handling

The Bromma TTDS can be used with all Bromma spreaders and other spreader brands. It is also available for both new orders and upgrades. To learn more about TTDS and if it is a solution for you, contact our sales representative.