Equipping an excavator for underwater or amphibious applications requires careful planning. While the applications will vary, they all have a couple of things in common - you will be working in environmentally sensitive areas, and the machines will be constantly exposed to water. This calls for some added precautions.
"Equip the excavator with an automatic greasing system," advises Matt Hendry, Deere & Company. "Water does not compress and will get in and force the grease out of pins/bushings. Small amounts of grease pumped into joints at regular intervals will lengthen [pin/bushing] life."
Lubricants should also be compatible with the environment. "We usually go with lithium grease for anything that is going to be extended life in the water," says Kent Pellegrini, Caterpillar.
Kokosing Construction Company Inc. is a large contractor that performs underwater excavation work around the Great Lakes. "We do a lot of water outflows and we lay pipe underwater," says Aaron Harke.
Because of the nature of its work, the company voluntarily takes precautions with lubricants. "We convert everything over to environmentally friendly materials," says Harke. "If we do have a hydraulic leak, we theoretically have not caused anybody any heartache. We just made a mess [that we] have to clean up."
Such steps provide peace of mind, says Harke. "As a manager, not having to worry about a hydraulic leak is a big deal," he says. "Things are going to fail. I don't care if you are on land or water, you need to be prepared for it."
Working near saltwater may require further adaptations of the equipment, such as specialized paint to minimize wear and corrosion. For issues unique to your jobsites, your equipment dealer is your best resource. "Dealers do a little extra depending upon what you're getting into," says Pellegrini.
Available options can further transform your excavators into highly efficient underwater tools. Take GPS grade control, for example.
Traditionally, Kokosing Construction has relied heavily on cranes with clamshell buckets for underwater excavation. But recently, it has been using excavators more for jobs where reach isn't an issue.
"Part of the reason is it has become so much easier to control grade and elevations," says Harke. "We installed Trimble systems on our excavators. That allows us to be within a couple tenths when we are digging with the excavator. That is a tremendous benefit.
"We have been easing into the whole GPS program for some time," he adds. It started with positioning of barges. "We know the barge is facing the right direction, so we could cut a straight trench and keep track of stationing."
The recent advancement of GPS with Real Time Kinematic (RTK) now allows Kokosing to more easily control grades and elevations. "It shows you the position of the bucket, so you know if you are teeth down or teeth up," Harke explains. "It has both plan and profile views when you are working, so the operator can toggle between them or he can set up two screens so he knows if he is on the centerline. He knows exactly where he is."
Obstacles are also easy to locate and mark. "When we are dredging and they run across a rock formation, they can put the bucket right on the rock and tell us within feet where it is in relation to the rest of the world," says Harke. "That is pretty helpful."
Caterpillar's AccuGrade system is also suited for underwater projects. "The AccuGrade really plays into this well in knowing where your slope is underwater," says Pellegrini. "You can stay within 5% to 10% deviation, if that is what the bid recommends."
Trying to account for all of the variables when working underwater can be daunting. "That is why you will see deviations from 5% to 10%, because they are usually adjusting for water rising or lowering or tides [going] in or out," says Pellegrini.