Caterpillar Inc., the world's biggest maker of earthmoving equipment, agreed to buy railroad repair company Progress Rail Services Inc. for $800 million in stock and cash.

Progress Rail is majority owned by One Equity Partners, JPMorgan Chase & Co.'s private equity arm, Peoria, Illinois- based Caterpillar said in a statement today. Albertville, Alabama-based Progress has 3,700 employees and had $1.2 billion in annual sales last year.

Caterpillar will pay 53 percent in cash, 47 percent in stock and assume about $200 million in debt. Progress Rail, which will keep its name, gives Caterpillar customers that include regional railroads, short lines, public transit authorities and private car owners. Caterpillar is trying to broaden its services and parts divisions.