The Jets acquired running back Kevan Barlow from the San Francisco 49ers yesterday for an undisclosed draft pick in 2007, their second attempt in a week to shore up the position.

The deal is contingent on Barlow passing a physical.

Last Monday, the Jets traded for Browns running back Lee Suggs, hoping to get help with Curtis Martin out. But Suggs failed his physical Tuesday and the deal was voided.The Jets are in desperate need of help at running back. Martin has been on the physically-unable-to-perform list since training camp opened with a lingering knee injury.

Though the 33-year-old Martin hopes to play again, his future is uncertain. The Jets have refused to disclose when Martin could return. Without him, the Jets have relied on Derrick Blaylock, Cedric Houston and rookie Leon Washington. The three played well in their preseason game Friday against Washington.

Blaylock ran for 46 yards on 10 carries, while Houston had 53 yards on 14 carries.

“We have been impressed with Kevan’s production in both the running and passing game,” Jets general manager Mike Tannenbaum said. “We feel Kevan will complement our running back group, and he will come in and compete for playing time.”

The 6-foot-1, 234-pound Barlow has 3,614 yards and 24 touchdowns in his career.

“This is a great opportunity for Kevan because of New York’s need at running back,” 49ers coach Mike Nolan said. “Kevan has been committed to our program and done well. With the depth at running back we felt we could make this move.”

Martin, the NFL’s fourth all-time leading rusher, underwent surgery on his right knee in December. He has yet to practice, and reports have said he has a “bone on bone” condition in his knee.

Still, Martin has been an ironman his entire career, known as much for his running as his ability to play through pain. When he went out last season, he broke a string of 119 consecutive regular-season starts and ended his streak of 10 straight 1,000-yard seasons to start a career, a record he shares with Barry Sanders.