The Orioles went after the free agent right-hander after learning that Kris Benson could be lost for the season with a partially torn rotator cuff.
Trachsel, 36, was 15-8 with a 4.97 ERA last season with the New York Mets. The 14-year major league veteran has a career record of 134-143 with a 4.28 ERA.
"Obviously, he brings a veteran presence and veteran leadership," Jim Duquette, Baltimore's vice president of baseball operations, said in a statement.
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"He's averaged 180 to 190 innings, with the exception of 2005, for the past six or seven years. That's exactly what we're lacking with the Benson injury."
Trachsel was expected at the Orioles' spring training camp at Fort Lauderdale Stadium on Friday
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