Below-the-Hook Lifting Beams for Cranes
- CP&A Staff
- May 4
- 4 min read
Updated: May 7
A business that works in the shadows of hulking cranes every day must also appreciate components, especially those below-the-hook.
Casper, Phillips & Associates Inc. (CP&A) recently completed a project where rail-mounted gantry (RMG) cranes had a lifting capacity of 40 long tons (2,240 lbs.), and both the trolley and gantry could travel at 150 m/min. The cranes spanned 175 ft. (approx. 53.34m) over nine rail tracks. They had a cantilever, giving the trolley a total travel distance of 213 ft. (approx. 65m) and the cranes a total length of 245 ft. (approx. 74.67m).
Who cares about the minutiae, then? Who’s interested in the meager when we’ve got the mighty?
Container Handling
“Container handling is a bit different in terms of below-the-hook,” says Richard Phillips, mechanical engineer at CP&A, a company that offers a wide variety of services, including procurement, specification, design, manufacturing review, modification, and accident investigation. “But, actually, we can use the industry as something of a barometer by which to measure safety and efficiency under the jib.”
He continues, “The biggest difference is that [for container handling] you have four independent hoist ropes. This enables the lift system to perform controlled trim, list, and skew operations to precisely pick up and place containers. Container cranes are built to pick up and move as much cargo as possible. The standard design of containers allows for much faster loading and unloading than below-the-hook equipment. But the principles are shared.
“Typically, container cranes are purchased with a second lifting device called a cargo beam. Depending on the specification, the cargo beam can have a single hook or multiple hooks. The beam connects to the headblock with either twist-locks or pins. The cargo beam is used for general non-containerized cargo since it has a hook, or multiple hooks.
Cargo Beams
“The standard lifting device on a container crane is called a spreader; it can lift standard containers. There can also be special spreaders that rotate the container or tilt the container to dump bulk material such as grain or coal. Think of the headblock as a universal mount where different lifting devices can be swapped in or out. The headblock also allows quick swapping of spreaders during normal operation if a spreader needs maintenance in the middle of unloading a ship, this minimizes the interruption.”
Phillips says below-the-hook lives from the point where the standard crane hook starts and ends at the load. There are “lots of reasons,” for the discussion turning from hook to special attachment to rigging gear. “One of the more common reasons,” Phillips says, “Is that the object being lifted needs to be supported a certain way. A simple example would be a long span truss; if you pick it up from the middle it is being loaded in a way that it may not be designed for. A special lifting device can help spread the load out and lift the truss from hard points.”
Sum-of-the-parts
There’s an irony to the fact that, as CP&A is contracted to work on or with large equipment, that the stakeholders involved have already placed huge importance on the rigging gear.
“When we are involved,” resumes Phillips, “There is usually a unique lifting requirement. This makes it obvious specialty equipment is required. We only get involved when it’s a one-off or has special requirements, where the off-the-shelf products won’t work. Contractors are very motivated to try to find the cheapest way to lift something, so I’m sure there is some effort to find a way to lift the load with the standard crane setup.
“Remember, as purely engineers, someone needs to build the equipment we design. A common arrangement for us is that a specialist doesn’t have any available engineers for a project, so they subcontract the above- or below-the-hook engineering to companies like us.”
At this sharp end of the industry, Phillips sees some good—exemplary, even—practice. And he points to slowdowns as a moment where the smart gets to work. All things below-the-hook are here given due consideration.
“Smart companies take advantage of slowdowns in engineering work,” he says. “They use this time putting their engineers to task designing new, innovative equipment, or even reducing the cost of their existing products. If there are no slowdowns and a company needs to innovate, they can hire outside engineers like us. Many countries recognize and understand the importance of having a licensed engineer from a country with a reputation for engineering excellence, and some of the best out there resides between hook and load.”
Bridging the gap
Casper, Phillips & Associates Inc. (CP&A) still revisits the Hong Kong-Zhuhai-Macau Bridge (HZMB) project when consulted on below-the-hook engineering. As the name suggests, Hong Kong, Macau, and Zhuhai, three major cities on the Pearl River Delta. CP&A was onsite in 2011 to observe the fabrication of the lift system that held the 8 pile drivers named “The Ocktakong”. At the time, the 34-mile bridge set world records, including a 72 ft diameter steel pile a world record at the time.
Richard Phillips, mechanical engineer at CP&A, recalls, “We designed a custom lift system that holds an array of eight vibrating pile drivers for driving the main columns of the bridge. A floating crane was used, which presented a huge area exposed to the wind load in addition to the motions of the vessel. Our team was able to overcome these challenges and the project was a success.”
