A team of New York University scientists has created a gear mechanism that relies on fluids to generate rotation. The invention holds potential for a new generation of mechanical devices that offer greater flexibility and durability than do existing gears—whose origins date back to ancient China.

"We invented new types of gears that engage by spinning up fluid rather than interlocking teeth—and we discovered new capabilities for controlling the rotation speed and even direction," says Jun Zhang, a professor of mathematics and physics at NYU and NYU Shanghai and the senior author of the paper.

Gears are among the oldest machine parts, dating back to 3,000 BCE in China, where they were used in two-wheeled chariots to cross the Gobi Desert. Over time, they've been deployed in the famous Antikythera mechanism, which predicted astronomical positions in ancient Greece, as well as in windmills, clocks, and, now, robotics.

However, gears' teeth, whether wood, metal, or plastic, are inflexible, so they are vulnerable to breaking—and they must interlock perfectly to work.