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Federal-Mogul says piston makes vehicles more fuel efficient

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Mike Gerulski
Mike Gerulski

SOUTHFIELD, Mich.—Federal-Mogul Powertrain has developed clutch piston technology that will allow vehicles with automatic or dual-clutch transmissions to become more fuel efficient.

The firm said its Unipiston allows transmission designers more flexibility, including increased clutch apply pressures, higher rotational clutch speeds and larger diameter clutches. These flexibilities enable transmissions with additional clutches to be packaged in a smaller space.

Federal-Mogul Powertrain—which is a division of Federal-Mogul Holdings Corp.—said it developed a new elastomer material and introduced a number of innovations into the molding process to produce the high-modulus bonded piston.

“What we were trying to do was to develop a material and a process combined that would allow us to take a high-modulus material similar to what we were using in the compression molding process and bring that to bear in products that are injection molded,” said Mike Gerulski, director, advanced technology for Federal-Mogul Powertrain Sealing and Gaskets.

While Gerulski would not divulge the exact nature of the new elastomer or the proprietary innovations the firm incorporated into the molding process, he said that the new material is like an ethylene acrylic rubber based polymer.

Federal-Mogul said conventional bonded piston seal materials manufactured using traditional injection molding techniques are limited in their modulus to about 10 megapascals, which results in challenges when filling the mold cavity.

Federal-Mogul's Unipiston has a modulus of more than 20 MPa.

Unipiston was developed in response to the ever-growing transmission requirements. Gerulski said customers have been evolving from what were four or six speed transmissions to eight, nine or 10 speeds.

“In some cases the clutches are getting larger in diameter, and the rotational speed is potentially higher, so the centrifugal force on the lift is increasing,” he said. “Having a higher-modulus material gives you the ability to handle those kinds of pressures better than if you had a like lower-modulus material.”

Gerulski said the next step for Federal-Mogul is to take Unipiston and expand it throughout its European base through some of its other customers in the region.

“I don't know that it will be required everywhere around the globe, but it certainly gives us some opportunity and flexibility to expand where we would not have been able to from a compression molding standpoint,” he said.