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Everything You Need To Know About Anti-Two-Block Warning System

Updated: Jun 21, 2019

Everything You Need To Know About Anti-Two-Block Warning System

Imagine there’s a lifting project being conducted on a construction site. A rigger and a crane operator are working together to complete the task.

The rigger was putting slings on the crane’s hook when the crane operator decided to extend the boom a little further.

But then, the hook and ball assembly got attached to the boom tip, putting extra stress on the hoist line.

While the workers were busy with their tasks, the hoist line suddenly snapped, causing the ball and hook to free-fall to the ground. Because the rigger was standing right below the assembly, he was severely injured!

What caused this accident? The reason behind it is two-blocking. Could the accident have been prevented? Yes, it could’ve been prevented if the rigger or the operator were paying close attention to the hook when the boom was being extended.

What’s Two Blocking?

Two blocking refers to a situation when a crane’s lower load block for instance the hook assembly, comes in contact with its upper load block, i.e. the boom tip. This can cause the hoist line to fail as it puts a lot of stress on the assembly and damages it.

According to statistics from 1984-94, 2% of all crane related deaths in the U.S construction industry were caused because of two-blocking.

The good news is that, technological advancements have made it extremely easy to prevent two-blocking accidents. With anti-two-blocking warning systems, crane operators can ensure the proper functioning of the machine and keep the hook from getting into contact with the boom tip.

Everything You Need To Know About Anti-Two-Block Warning System

Anti-Two-Blocking Warning Systems

According to the ASME, American National Standards for Mobile and Locomotive Cranes, every crane manufactured after second February 1992, must have an anti-two-blocking warning system installed.

The two most popular types of anti-two-blocking warning systems are wireless and hardwired ATB system.

Wireless ATB systems

Wireless anti-two-blocking warning systems don’t have cable reels to go up to the boom. These easy-to-install devices are one of the best designs on the market, as they provide both audio and visual alarms to indicate that the crane’s hook has reached the maximum safe height.

If your operations don’t require lifting personnel and you have a telescopic or lattice boom crane, then a wireless crane ATB system is the perfect option for you.

Hardwired ATB Systems

Just like the wireless ATB systems, Hardwired systems also provide audio and visuals alarms when hook get to the maximum safe height. This gives the operator a much needed heads up to prevent the hook assembly to cinch up with the boom tip.

This type of ATB system has a cable which makes it perfect for fixed boom cranes. If your operations require lifting personnel and using a lock-out then you should get a hardwired ATB system for your crane.

Both types of ATB Warning systems are cost-effective for guarding against boom damage and accidents and are the minimum safety indicator all cranes should have!

Get in touch with Crane Warning Systems Atlanta to purchase high-quality ATB Warning Systems today!

Besides ATB warning systems, we’ve also been providing safe load indicator system, wind-speed indicators, two-way-radios and camera systems, to clients for the past two decades!

Contact us today for more information.

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