COLUMBUS, Ohio (AP) _ Bus service resumed Tuesday for 90,000 daily riders after a court order provided at least a three-day break from the 2-month-old strike by drivers and mechanics.

But both sides in the dispute said resumption of service did not mean a resolution of differences.

Buses began running as scheduled about 4:30 a.m., Central Ohio Transit Authority general manager Richard Simonetta said.

''It's been going very smoothly,'' transit authority spokeswoman Mari-jean Porterfield said Tuesday afternoon. ''The buses got out on time, and everybody showed up for work.''

She said ridership was lighter than normal, which was expected because of uncertainty about how long bus service would continue.

The strikers returned to work under an order issued Sunday by Franklin County Common Pleas Judge Frederick T. Williams. The judge accepted the transit authority's argument that the strike may be a threat to public health and safety.

But the order expires at 12:01 a.m. Friday. Under the state's public employees collective bargaining law, the State Employment Relations Board must make the final decision on whether the strike hurts the public welfare.

Late Tuesday, the transit authority filed a petition with the Franklin County Court of Appeals asking it to prohibit the board from conducting a hearing set for Wednesday morning.

The petition claims that jurisdiction lies with Williams. But if the appeals court disagrees, the state board's decision still will be sent back to Williams, who could continue the back-to-work order for 60 days or cancel it.

No negotiations are scheduled in the strike, which began Dec. 9 over wage and holiday issues and use of part-time workers. Top scale for drivers is $12.31 an hour. The top hourly rate for mechanics is $13.33.

The union has sought a 15 percent wage increase over three years. The transit authority has offered a 5.3 percent raise and a cost-of-living adjustment.