WASHINGTON – Amtrak cobbled together enough cars and equipment Saturday to run regular trains on the four Acela Express trips scheduled between Washington and Boston after brake problems forced the beleaguered passenger railroad on Friday to suspend high-speed service in the Northeast at least through Wednesday and probably for more than two months.

But just one high-speed train was to be back in service today, according to Amtrak spokeswoman Tracy Connell.

She said the 8 a.m. Acela Express from New York to Washington will operate today and be turned around to make a 2 p.m. run from Washington to Boston.

She said crews were working around the clock to inspect and repair other express equipment and hoped to be able to place a second high-speed train back in service today.

Yesterday, the railroad planned to run three out of its 10 Acela trips with substitute trains, Ms. Connell said.

Amtrak normally runs 15 Acela weekday roundtrips between New York and Washington and 11 between New York and Boston.

The Acela trains are built by Bombardier, Inc., based at Montreal, and the brakes are under warranty. Bombardier has started to replace some parts and has brought in extra people who are working 24 hours a day in Washington, Boston and New York to replace the faulty brakes, Helene Gagnon, a company spokeswoman in Quebec, said Saturday.

Millimeter-sized cracks were found in 300 of the Acela fleet’s 1,440 disc brake rotors. The problem surfaced when a Federal Railroad Administration worker did a routine inspection Thursday night after a high-speed run to test whether Amtrak could speed up the Acela trains slightly in New Jersey on curves between Trenton and Newark.

Amtrak’s 20 Acela trains each have 72 brakes.

Acela accounts for about one-fifth of Amtrak’s service along the Northeast corridor, carrying an average of between 9,000 and 10,000 riders on weekdays.

Ms. Gagnon said that Bombardier was still trying to determine what caused the brakes to crack. No decision has been made yet who will pay for the repairs.