Mack Trucks and its corporate parent, Volvo, have agreed to pay $525 million to settle a class action suit brought by more than 9,300 Mack retirees to challenge threatened reductions to their lifetime health benefits.

Senior U.S. District Judge R. Barclay Surrick has granted preliminary approval of the settlement in Mack Trucks Inc. v. United Auto Workers and has scheduled a hearing for Sept. 7 to consider whether it is fair and reasonable.