The Montgomery County Library Board has warned that if the tax-cutting charter amendment known as TRIM (Tax Relief in Montgomery) passes in November, the county would have to close five libraries and require several others to operate part time.

While declining to take an official stand on TRIM, which is Question E on the ballot, the Library Board said in a press release that it unanimously opposes the $700,000 in library reductions that TRIM would force.

Hazel Snyder, former board chairman, said that most of the savings would be achieved by curtailing library service. Snyder's term as chairman ended last week when the board elected Donald Roha to replace her. She will remain as a board member.

The Four Corners, Potomac, Sherwood, Noyes and Western County branches would be closed, she said. Twenty hours would be eliminated weekly from the operating times of Silver Spring, Chevy Chase, Kensington Park, Little Falls, Long Branch and Twinbrook.

They would be open three days a week from 1 to 9 p.m. and three days from 9 a.m. to 5 p.m. Friday night service would stop at Aspen Hill, Bethesda, Davis, Gaithesburg, Rockville, Wheaton and White Oak.

In addition, the rental collection and certain reference services would end and purchases of films and phonograph records would be cut by half, according to the library board. The reductions also would result in the firming of 60 employes, the board said.