The components are not made at the Centre, of course, but transported there from the contractors’ factories. Nonetheless, they still need to be lifted at the Centre to run tests or for storage.
For example, NASA engineers need to make sure that elements of the international space station, each built by a different supplier, connect properly. One good way to do that is with a pair of overhead cranes. Cranes also lift space shuttle engine assemblies into, and out of, pressure testing machines. Others service satellites and other payloads. Still others organise storage in warehouses.
The Marshall space flight centre facility consists of dozens of buildings, each with its own overhead crane. There are about 300 cranes on site.
“Sometimes NASA doesn’t tell you; they get the building ready for a top-secret project before the flight hardware is arriving,” says Jeff Daugherty, sales engineer for local crane builder Atlanta Crane and Automated Handling.
“Every building is set up to do a particular test that NASA wants done,” Daugherty adds. “Because we know we are going to get this part of the mission, they will go ahead and start refurbishing the cranes.”
Daugherty worked with crane builder Andress Engineering to get the contract to refurbish four 45/45 US ton (81t) capacity cranes last year. “One of the cranes was lifting segments of the space station. These sections are worth hundreds of millions of dollars. You have to make sure the cranes are 100% before they make lifts,” he says. These cranes had 130ft (40m) bridges and had 90ft (27m) of lift.
NASA certifies cranes that are lifting flight hardware as ‘critical-lift cranes’ – and it requires redundancies to improve safety and reduce the chances of dropping a load. As part of this spec, maintenance contractor EG&G inspects these cranes every month.
Atlanta won the competitive tender to refurbish five double-girder cranes at the facility, with lifting capacities ranging from 5 US tons to 35 US tons (4t-32t), including two 30/5 cranes for pressure testing. Spans range from 60ft (18m) for the 5 US ton crane down to 28ft (9m) for the 7.5 US ton crane.
All of the cranes lift with R&M SX wire rope hoists with several special features. They feature frequency-controlled motion in all directions, an extra drum brake, and paddle upper limit switch that must be manually reset.
“Operators get used to working with the crane, and they don’t keep the load in sight – when it clicks, they let go of the button,” Daugherty says.
Atlanta installed Drivecon travel drives for long and cross-travel motion. The closed-loop vector drives use wheels to measure their position along the girders.
The contract calls for the steel structure to be stripped of components, testing the support structure for fatigue cracks, and installing new hardware and controls. Then Atlanta grinds down rough surfaces on the structure and repaints it.
“Most of these cranes were installed 30 or 40 years ago,” says Dennis Bethel, Atlanta Crane president. “The control panels are the size of small homes. They’re old. A lot of their efficiencies are gone. They have been idle a long time, been used once in a while, and now they are going into production.”
The R&M hoists are so much lighter than the equipment being replaced that they can actually increase the life of the crane, Bethel says. “We’re cutting more than half the weight on the crane sometimes.
“We keep the old redundancies that they wanted and convert the controls to AC variable frequency. In addition, now they are more electrically efficient and consume less power.”
Atlanta Crane and Automated Handling sells R&M and Demag cranes and hoists, Gorbel light cranes, and supplies Insul-8 conductor systems. Its other large customers include Nissan, Michelin, JVC and John Deere.
