Anti-Two Block system reduces risk of dropped loads

Over the years, the offshore and marine industry has witnessed multiple crane incidents and dropped loads due to two-block collisions. To address this problem, Keppel LeTourneau developed a simple yet innovative solution to reduce the risk of dropped loads. The company says that the result is an Anti-Two Block system (A2B) that can be modified to fit most cranes in the market today.

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Over theyears, the offshore and marine industry has witnessed multiple crane incidents and dropped loads due to two-block collisions. To address this problem, Keppel LeTourneau developed a simple yet innovative solution to reduce the risk of dropped loads.

The company says that the result is an Anti-Two Block system (A2B) that can be modified to fit most cranes in the market today.

Weighing under 50 lbs and with a compact body, the newly designed A2B can be installed on all LeTourneau cranes and is also customizable to other brands upon request. It has an expected life span of over 10 years and is made of forged stainless steel and high impact polymer to resist corrosion.

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A distinguishing feature of the A2B system are the versatile and reliable sensors that are not dependent on chain length or weight unlike other A2B designs.

The company says that the A2B utilizes a dual chain suspension system which ensures that it is highly resistant to spinning, thereby preventing it from being dragged up by the wire rope. On top of this, the wide stabilizing arms cater for high winds, and pitch and roll motions.

A distinguishing feature of the A2B is its versatile and reliable sensors, says Keppel LeTourneau. The redundant NAMUR proximity sensors are integrated in an easily replaceable cap and the activation of limit sensors is not dependent on chain length or weight unlike other A2B designs.

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The newly designed A2B with field adjustable chains that allows for flexible stopping distances for a variety of applications. (Images courtesy Keppel LeTourneau)

The innovative design also allows for the A2B to be installed without removing the block and disconnecting the wire rope. The A2B interlocks onto the wire rope with multiple fasteners and will not come off the wire rope if the chains break or if several fasteners are removed.

One of the key advantages of the newly upgraded A2B is that it can be visually inspected without disassembly. Unlike existing systems in the market, this A2B has no springs, seals, lubrication, precision wear points or mechanical switches, making it practically maintenance free. It is resistant to wire rope lubricant, sand, water, ice and other contaminants that normally disable other A2B designs. •

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