Different Twistlocks on containers
Twistlocks are devices used for securing containers to the deck or to other containers. While the design principles and functionalities of all twist locks are similar, their specific positions and roles may vary in practical applications. In maritime transport, there are three common types of twistlocks used for container fastening: manual twistlocks, semi-automatic twistlocks, and fully automatic twistlocks. Clear differences and understanding specific applications of twistlocks can greatly enhance the safety of your maritime transportation.
Overview
Manual Twistlocks:
The end of the twistlock is mushroom-shaped. When in use, the twistlock is first inserted into the bottom holes of the four corner castings of the container, and then the handle is pushed and twisted 90° to lock the container. Dovetail bottom twistlocks can only be used with dovetail bottom foundations.
Semi-automatic Twistlocks:
During loading, when the container is lifted to a height equivalent to a person raising their arm, the semi-automatic twist lock is inserted from below into the corner casting of the container. Once the container is lifted onto the ship and aligned with the protruding base or another corner casting of the container, and the lock's automatic mechanism engages, securing the connection with the container. When unloading the container, the operator uses a control rod to pull out the lock pin, opening the twist lock and releasing the connection with the protruding base or another top corner casting of the container. The twist lock is then removed when the container is lowered to the terminal by the personnel.
Fully Automatic Twistlocks:
One end of the twist lock is spiral-shaped. When the container's weight is applied to the spiral-shaped lock head, it generates a torque, causing the lock head to rotate automatically and secure the connection between containers. When the container is lifted, the twistlock unlocks under the force of a spring.
The positions of twistlocks and stackers
1：mid twistlock
2：stacking cone
3：bottom stacking cone
4：double stacking cone
5：bottom twistlock
6：flush bottom twistlock
7，8：dovetail bottom twistlock
9：automatic bottom twistlock
10：automatic mid twistlock
11：height compensator
12：bridge compensating stacking cone
13：bridge fitting
14：high-low container bridge fitting
15：semi-automatic twistlock
