Kyle Shanahan, who added veteran center Alex Mack to his offense a year ago, has made a similar move this year with the 49ers.
The team traded for Ravens center Jeremy Zuttah, 30, who made the Pro Bowl as an alternate this past season but who was set to be released by Baltimore because of salary-cap reasons.
The Ravens web site reported that the 49ers, who have more salary-cap space than any other team, will take on Zuttah's salary. Zuttah has two years remaining on his current contract. The teams also will swap sixth-round picks in the upcoming draft; The Ravens get pick No.