The Montgomery County Board of Education, constrained by a tight economy and orders from county officials to lower its sights, grimly slashed the 1991-92 school budget yesterday while complaining that the cuts would erode programs at all levels of the system.

One new school board member cried openly, saying the county's fiscal crisis had dashed her election-year promises to improve Montgomery's well-regarded schools.

"There is no way we cannot hurt kids," said member Carol Fanconi, her eyes filling with tears. "I am angry about having to cut into something I care very deeply about."

In a preliminary round of cuts yesterday, board members decided to eliminate all but $900,000 of the $4 million that Superintendent Harry Pitt had recommended in initiatives. As a result, school officials said they will abandon plans to make elementary school classes smaller, to add elementary school counselors and to create more all-day kindergarten classes.

"This one is a real killer," board President Blair Ewing said after voting to reduce the kindergarten expenditures, one of his priorities during 14 years on the board.

In an 8 1/2-hour session that lasted late into the evening, board members pored over the budget page by page, debating how to cut the school system's programs in ways that would hurt children the least.

By the time they quit, they had tentatively pared $18 million -- an unprecedented amount -- from the $782 million budget that Pitt proposed last month. The board cut funds for field trips in half, ordered central administration reduced by 5 percent, and decided not to buy 16 buses -- a savings that will force some elementary schools to start earlier or end later.

The board also voted preliminarily to abolish one of the school system's four regional offices, a major change in the organization of the 103,500-student system.

Although they had planned to adopt final recommendations last night, board members decided to continue next week, when they will take up some of the most delicate questions, including whether to eliminate one of seven class periods in county high schools.

Pitt said the school system "got beaten up pretty good tonight," but cautioned the cuts may need to be still more dire.end. I want to make that very clear," he said.END NOTES

The superintendent's initial budget proposal, an 11 percent increase over current spending, was intended to pay for a few initiatives and accommodate an expected influx of 5,000 students next year.

Pitt's spending plan drew immediate criticism, however, from County Council members and County Executive Neal Potter, who said it was out of step with the county's financial circumstances. Potter has said the school system may have to carve as much as $70 million from the superintendent's proposal, a sum several times larger than any previous cuts in the school budget.

Trying to comply with political realities, the board broke sharply yesterday with local tradition, in which board members have added to the superintendent's recommendations before sending their budgetary advice to the county executive. The executive gives his recommendation, in turn, to the council, which must adopt a final version by mid-May. The school system accounts for more than half of county expenditures.

In an unprecedented move, Pitt advised the board to make millions of dollars in cuts in his own proposal. But the superintendent, who has prided himself on conciliatory budget dealings with the county government, said the reductions Potter envisions would break state law.

The superintendent, who plans to retire in June, said the cut would violate a state requirement that school systems spend at least as much on each pupil as they did the previous year. As a result, he said, the school system could jeopardize its state aid and ruin Montgomery's reputation as a county in which education is paramount.

"That is a legimate concern. We are very concerned about that," said County Council member Michael L. Subin, who leads the council's Education Committee.

Board members also contended that the council needed to ease the revenue crisis. The school board voted unanimously to urge the council to override a November referendum that limits property tax increases to the rate of inflation, in order for the council to raise an additional $70 million. The reversal would require the approval of seven of the council's nine members.

One of the board's few additions to Pitt's proposal was to its own staff. Complaining that it was overworked and, with four new members, underinformed, the board voted to give itself a staff analyst.

As a result of the grim financial picture, the board's budget decisions had several odd political twists.

In the past, board member Ewing has criticized Pitt's budget proposals as unimaginative and inadequate. But in his new role as board president, Ewing said cuts were inevitable and praised the outgoing superintendent, saying, "Dr. Pitt's budget is responsible in terms of what it does for education."

The budget problems also jarred the board's new members. "We just came out of campaigns talking about our visions for the future and our priorities," said Frances Brenneman. "Now we are in a position where some of our visions might not come to fruition. It is a very unpleasant task."