What is a Twistlock?
A Twistlock is a device for securing a shipping container into place on a ship, a truck or trailer and on rail carriages.
Each industry, Shipping, Rail Transport and Road Transport, all use similar but different styles of twistlocks.
They all do the same job but are slightly different in their design.
The basic make up of a twistlock consists of a couple of different sections.
They all have some sort of housing, a throw bolt or guts & the handle to lock the twistlock in place.
On a container, the corners both top and bottom, have a corner cast. This corner cast has a female opening that the twistlock fits into and then the head of the bolt or guts, twists and therefore locks the twistlock and container together. The head of the twistlock is shaped so that when it is engaged, it can’t release the container until it is physically disengaged
Marine twistlocks are generally welded to the deck of a Ship or a base plate can be welded to the deck and the twistlock is then mounted into the base plate. The purpose of the twistlock in shipping is to keep the container restrained to the deck. Along with other measure like locking bars, turnbuckles and double stacking twistlocks, ships can mount multiple containers on top of one another with relative safety.
Marine Twistlocks come in a range of shapes for different applications but all work on the same basic principle.
They are usually manually locked and unlocked by moving the handle from side to side.
Rail Twistlocks are a little different to Marine Twistlocks as they tend to be automatic or semi-automatic when they are engaging with the container. The basic principle is the same but because of the sheer length and amount of carriages available, it would be very time consuming and labour intensive to manually lock and unlock the four corners of each container.
These are typically operated in conjunction with the carriages air brake system.
Truck Twistlocks are the most basic of the Twistlock range. They consist of a housing that is welded to the truck bed or to the corners of a trailer. Trailers could be a multi-purpose flat bed or a Skel trailer – specifically designed to carry containers.
Like the other forms of twistlock, the container is lowered onto the twistlock and then the bolt or guts, is positioned so that the head of the twistlock is sitting inside the corner cast. It is then engaged by moving the handle to the side and therefore turning the head to engage the container. No other form of restraint is required with all 4 corners locked into position.
With the truck twistlock, the 3 main components can be replaced. The housing, the bolt or guts and the handles. Handles come in different styles and lengths. There are also extensions that can be used as well as spacer blocks, for when the container does not sit horizontally flat. This could be due to the trailer’s configuration ie: a drop deck trailer.
When you need to stack multiple containers on top of each other, Double Stacking Twistlocks are used in conjunction with other securement items.
The basic operation of the Double Stacking Twistlock is similar to a normal twistlock except it has 2 locking heads mounted top and bottom. The twistlock is mounted into the top corner cast and positioned so that another container can be placed on top. Once the 2 containers are in position, the twistlock can be engaged to secure both containers together.
Depending on the situation and environment, other devises should be used to ensure that the containers remain secure.
Bridge fittings are a type of turn buckle that locks containers together horizontally. They mount on top of the 2 containers and have a threaded bar with hooks on each end. When the hooks are in place, turning the threaded bar brings the hooks together, pulling the containers together. Locking bars, turnbuckles and other restraining devices can also be used, especially in a high wind or unstable environment
ANC Distributions carry a range of twistlocks for both Marine and Road Transport.
We also stock accessories like Double Stacking Twistlocks, Bridge Fittings, Container Bolt Seals, Container Replacement Parts,
Desiccants and Container Care products for securing and maintaining goods inside the container.