Swedish machinery manufacturer Atlas Copco AB agreed to sell the bulk of its U.S. equipment rental business for $3.8 billion to private equity firms Ripplewood Holdings LLC and Oak Hill Capital Management LLC .

Atlas Copco, the world's largest manufacturer of air compressors, will keep 14.5 percent of RSC Equipment Rental , which it created by purchasing several machine rental businesses in the 1990s.

Scottsdale, Ariz.-based RSC is the second-largest construction equipment rental company in the United States, after Greenwich, Conn.-based United Rentals .

Atlas Copco said it decided to sell RSC because construction equipment rental is not a good fit for its industrial equipment operations. The company will focus on making building and mining machinery, said president and CEO Gunnar Brock.

“We are very satisfied with the deal. It results in substantial cash proceeds, a capital gain and a minority stake in the best equipment rental company in North America,” Brock said in a statement. “With three very strong, very profitable industrial business areas, all with leading market positions, Atlas Copco will have excellent opportunities for strong growth and value creation.”

Atlas Copco will receive about $3.3 billion in cash and the remainder in securities from the deal, which is the third major acquisition this year in the equipment rental market.

In May, the New York City-based private equity firm Diamond Castle Holding LLC bought NES Rental of Chicago for $850 million.

And in July, the British owner of Charlotte, N.C.-based Sunbelt Rental bought NationsRent Co. of Ft. Lauderdale, Fla., for $600 million, making it the country's third-largest equipment rental company.