Metro officials said Monday that crews had completed inspections of brake assemblies on 464 rail cars in its 2000- , 3000- and 4000-series rail cars after an incident last week in which a brake part fell off of a rail car.

Over the weekend, Metro said the rail cars were inspected.

The review came after an incident Friday in which a friction ring detached from an Orange Line train. The cause of that incident remains under investigation.

Metro said over the weekend that it has “taken the precaution of replacing more than 290 friction rings from brake assemblies that are showing wear.” They said that effort “exceed the standards set by the original equipment manufacturer.”

Dan Stessel, Metro’s chief spokesman, said Monday that the replacement of the friction rings was done from “an abundance of caution.”

He said the replaced rings represent about 8 percent of the rings on the 464 cars.

He said Friday’s incident is different from an earlier incident in which a friction ring fell off of a 5000-series rail car.

“They’re both friction rings,” he said. But Friday’s ring is a “different type of manufacturer, different design, and it was on a different type of car.” He said the way the friction ring “broke away” in Friday’s incident was also different.

“While we’re working to identify the cause,” he said, “anytime we identify wear, we will replace a ring.”

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