Twist lock

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The standardized container corner (corner casting) enables easy stacking and loading.

Twist locks ( twist Engl. For "twist" lock Engl. For "Castle") are locks that swap bodies or ISO containers with each other and / or connect to the carrier vehicle. The twistlocks are inserted into the standardized corner fittings (corner castings) of the container or the container is placed on the locks that are fixed to the vehicle. Then part of the twistlock is turned by 90 °, creating a positive connection.

The locking direction of the twistlocks is different. Left-locking twistlocks are common in Europe, right-locking twistlocks in the USA.


Land vehicles have lowerable and non-lowerable (foldable) locks that are often permanently connected to the vehicle. The container locking (twistlock) on a truck semi-trailer is done with a handwheel and safety device.


Various elements are used in shipping to secure containers on deck or in the hold. Twistlocks differ according to their place of use and the type of ship and are then referred to differently. On container ships, for example for securing the container to cover the normal to (ordinary) twistlocks used. They have a conical shape at each end and together with the shaft form the vertical axis to be rotated, which is brought into the locked position after being rotated by 90 ° . Twistlock foundations or pockets are attached to the hatch covers . One side of the twistlock is inserted into this recess. A container is placed on the twistlock from above, the upper end of which is now in a corner casting . Now the vertical axis of the twistlock is turned. Due to the shape of the twistlock ends, the container is now firmly connected to the hatch cover at this corner. Each container is secured with four twist locks.

With other types of ships (e.g. multi-purpose ships ) that are not only designed for container travel, there may be other types of twistlocks, as the twistlock foundations on deck or on the hatch cover interfere with the transport of other cargo can. Here you use bottom or sliding twist locks . These are in dovetail foundations (dovetail foundations) pushed. The system is similar to a foot that is put into a shoe. This twistlock looks like the normal twistlock on the upper half, but has only one plate on the lower side, which is pushed into the foundation on the deck or hatch cover.

Automatic twist locks

Originally, the twistlocks were inserted into the container or the deck fittings from above, then the container was put on and the locking mechanism was operated mechanically. For reasons of accident prevention, the development went from semi-automatic to fully automatic twist locks. These are hooked into the lower corner fittings (corner castings) of the container hanging on the container bridge. They lock and unlock automatically (corresponding pulling force of the bridge with vibrations of the contents) when they snap into the corresponding fittings of the already standing container.

Further material on container securing

Double cone
for connecting containers to each other in order to achieve block jams. Today it is hardly used any more, as this type of load securing makes it necessary to stow the remaining load when partially unloading cargo.
Bridge fitting
are connecting pieces that are placed in the last container layer. With bridge fittings, containers are connected transversely or longitudinally, depending on the fitting type. They are used to achieve a positive connection and greater load stability.
The construction of large container ships with a flat stern implies the risk that breakers rolling under the ship cause strong vertical acceleration forces. The twistlocks with which the stacked containers are attached to one another are not designed for this; they work against horizontal forces. Therefore bridge fittings are used to secure individual container towers. Cases like that of the large container ship MSC Zoe (loss of 345 containers) have shown that this is necessary.

See also

Bayonet lock


  1. June 21, 2019: Risk management on container ships