Originally Published MPMN January/February 2008

ENGINEERING SOLUTIONS

Linear Rails Bear the Weight of Revamped X-Ray Table

Redesigned for use with overweight patients, an imaging table required rails with a high load capacity and extended stroke.

When Arcoma (Växjö, Sweden; www.arcoma.se), a provider of automatic x-ray equipment, originally designed its mobile imaging table, it aimed to create a flexible system that was easy to operate and kept the ergonomics of the hospital staff in mind. With a minimum table height of only 55.5 cm, the low tabletop enables patients to sit down easily, which increases their feeling of security while hospital staff avoid heavy lifting. Most importantly, the table is configured to allow radiographs on trauma patients without having to reposition them.

However, several pain management and orthopedic studies revealed new applications for the table that would require modifications in order to support obese patients and comply with associated FDA requirements. In light of the new weight-based demands, the company sought to alter the design so that the table could support up to 500 lb.

Facing the challenge of redesigning one of its flagship products, Arcoma delegated the reworking of the system to its California-based tech support and service center. “The increased load capacity would have been too great a strain on our existing tables, so the key was to find a linear motion system that could not only hold weight, but also had a long enough stroke for the applications,” says Brian Gogan, executive vice president of Arcoma North America. “Because the tables move around the imaging equipment, rather than moving the patients themselves, there is a huge extended load on the bearings, and the stress on the parts can be tremendous.” Along with extra load capacity, the system needed a reliable linear bearing system, Gogan adds.

Arcoma investigated several linear motion options and finally partnered with Rollon Corp. (Sparta, NJ; www.rollon.com). The linear motion product supplier brought to the table its telescopic rails, which feature the load capacity and extended stroke desired for the redesign.

“Drawer slides [traditionally] were simple bent-steel products suited for desk drawers, filing cabinets, keyboard trays, and other light-duty applications,” explains Rollon general manager Andrew Cook.
“In fields where high load capacities, reliability, low deflection, and smoothness of movement are important for a drawer-slide-type extension, there was no solution.

“By creating the telescopic rail family, Rollon’s engineers succeeded in creating a telescopic linear bearing––similar in movement to a drawer slide, but closer in function to a linear bearing,” Cook says.

Demonstrating the necessary flexibility for mobile imaging with reach strokes of more than 200 cm, the slides also showed zero deflection despite extremely high loading during testing phases, according to Gogan. “They also have 60 hardness rating raceways to ensure a smooth movement, which is critical for patient safety and comfort,” he notes.

Incorporating Rollon’s telescopic rails into its mobile imaging table enabled Arcoma to achieve the desired flexibility and weight capacity, while maintaining the features that had originally established the system on the market. The modified system was introduced to the marketplace in 2007.

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