Rock around the clock

New York -The new G300 polymer bearing material from igus (East Providence, RI) is helping New Yorkers keep accurate time. The bearing material keeps custom clocks from Electric Time (Medfield, MA) running outside of the Tourneau Store.

Electric Time's outdoor clocks are regularly subjected to temperature changes from well below freezing to above 100F, rain, snow, and debris carried by the wind.

The company's design engineer Mike Elson grew dissatisfied with bronze bearings because they tended to seize when exposed to the elements. Lubrication eliminated the seizing, but created another problem-oil leaking onto the clock face, requiring servicing, which is something that both Electric Time and Tourneau wanted to avoid. "A lack of oil and maintenance were primary reasons for selecting the G300 material," says Elson. "And the igus polymer also dampens vibration from the wind."

The new bearing material is a combination of solid lubricants such as Teflon or silicone, polymer alloys, and "fiber". During the clock's break-in phase, microscopic abrasion transfers solid lubricants from the bearing to the shaft surface. Eventually, the shaft surface becomes saturated with dry lubricant, and then rides on the lubricant buildup. The profile of the shaft surface fills with solid lubricant that lasts for the life of the bearing.

"Since switching to these bearings, we have not had any movements fail due to seized shafting," says Elson. The company is in the process of completing the changeover to the new bearing material within the next year.