BREMERTON, Wash. –
Cranes could be considered part of the Puget Sound Naval Shipyard & Intermediate Maintenance Facility “brand” due to their visibility throughout the local community. People all around Sinclair Inlet can regularly see various portal cranes at PSNS & IMF trundling about, carrying large objects. Conversely, the Hammerhead Crane is one of the first large and stationary things ferry passengers see when they exit Rich Passage on their way to Bremerton.
While cranes are one of most essential pieces of heavy equipment at a shipyard, the professionals in Code 700, Lifting and Handling, actually have a wide variety of ways to lift and move very heavy things. One of the most versatile pieces of equipment they use is a self-propelled modular transporter.
SPMTs look a bit like the trailers towed behind semi-trucks, except they have rows of wheels running their entire length. A qualified operator wearing a wireless remote controlled device called a “belly box” walks beside the SPMT.
According to Joe Mick-Hager, Material Handling Equipment supervisor, Code 740, Rigging & Operations, PSNS & IMF, an SPMT is actually comprised of two different units; a module and a power pack. They can be used together in various configurations to move very heavy things, very precisely, just about anywhere. Each six-axle trailer has a working load limit of 240,000 pounds, and they can be used in tight spaces, including inside dry docks.
“SPMTs are made up of individual units called ‘modules’ that can be connected — both longitudinally and laterally — to create larger platforms tailored to the specific loads,” Mick-Hager said. “Each trailer has its own set of wheels that can turn independently, which allows for omnidirectional movement.”
“This is all controlled by a sophisticated computer system,” he continued. “The trailers have a hydraulic suspension system that controls the platform height by using hydraulics, ensuring stability and even weight distribution across all modules. They do not have a built-in crane or ramp, so forklifts or cranes are used set the load onto the trailer.”
According to Mick-Hager, PSNS & IMF is continually finding new things SPMTs can be used to lift or move.
“From lifting an entire aft submarine assembly and enclosure weighing in at just under 300,000 pounds, to carrying an empty CONEX box, they can do anything,” he said. “When we initially got the units in 2020, we put out that if someone thought we could move something with an SPMT, let us know. That list just keeps growing. We have been able to modify lifting and handling processes by using SPMTs that have saved the command hundreds of man hours, sometimes on a single process.”
Mick-Hager credits the versatility of SPMTs for much of the savings.
“They have a little bit of crane in them, some forklift, a touch of high-lift platform and some flatbed tractor-trailer too,” said Mick-Hager. “Plain and simple though, they are mobile and adaptable. Our portal cranes are restricted to our crane rails, and our mobile cranes cannot drive on their wheels with a load attached to the hook. Loads can be placed onto the SPMT and be transported to their final destination anywhere in the shipyard.”
Mick-Hager said an SPMT isn’t always the right tool for the job. Which material handling equipment Code 700 uses, depends on the size and weight of the item being moved. If an item fits on a flatbed trailer and it has the capacity, a flatbed trailer would most likely be the correct choice. The SPMT’s are used for very different things than flatbed trailers.
“These machines can be used to transport material, but their main function is to assist with installation and removal of large and/or heavy items on the ships and submarines,” he said. “The uses are not limited to that. If there is a use for the SPMT and it is the correct tool for the job, we will utilize it. There are a lot of things to like about them, but if I were to narrow it down to one thing, it would be the carrying capacity and how maneuverable they are.”
According to Mick-Hager, Code 700 has 19 qualified operators, and Code 730, Crane Maintenance Division, has 10 qualified operators. These professionals, who must complete a week-long certification course, work across all shifts at the command. They not only have to know the operating characteristics of the SPMTs, they also need to know how the hydraulic system works and how to properly set up the unit. They have to know how to adjust the hydraulic system and how to properly set up the programing on them. Code 730 has a team of qualified operators who have also received additional training to maintain and troubleshoot problems with the units.
“Code 730 handles everything on the maintenance side, from scheduled maintenance, troubleshooting issues, weight testing and assistance to set up or assemble the units,” said Mick-Hager. “Whether it’s connecting the PPU to the trailer, connecting multiple trailers together or the initial valve set up."