LOGAN, W.Va. (AP) _ United Mine Workers leaders are urging striking members to remain peaceful in their efforts to force the Pittston Coal Group Inc. to sign a contract.

About 1,500 UMW members gathered this morning for what had been billed as a rally at a football field. The meeting was moved into Logan Memorial Field House, and union officials barred reporters.

Danny Wells, who becomes a UMW District 17 international board member Saturday, said the miners wanted to discuss certain matters in private. He would not say what those issues were.

Four coal trucks in West Virginia and Virginia have been hit by bullets this week and two others damaged by steel balls fired from slingshots, police said. Striking Pittston employees and wildcat sympathy strikers blocked traffic on coal-hauling roads Thursday. No arrests were reported, but Pittston said a security employee suffered a cut on his head in a confrontation.

''We are doing our best to make sure our people are still in a non-violent frame of mind,'' said Roger Horton, vice president of UMW Local 5958 in Dehue. ''We cannot win with any type of violence.''

Horton was an organizer of the meeting today in support of 1,900 union members on strike against Pittston in West Virginia, Virginia and Kentucky.

At Elkem Metals Co. in Alloy this morning, 300 members of the Oil, Chemical and Atomic Workers union walked off the job for half an hour in support of the Pittston strikers.

''We're willing to tolerate it if it's limited to 30 minutes,'' said Gary Moore, the plant's employee relations manager.

The Pittston workers went on strike peacefully in April after 14 months without a contract. But there have been scattered violent incidents since thousands of union miners in Appalachia and the Midwest went on a wildcat strike in sympathy with the Pittston workers 2 1/2 weeks ago.

Union and coal company officials estimate about 37,000 miners in eight states are on strike, although the start of the traditional summer vacation period this week has made it difficult to determine precise numbers. States affected include Alabama, Illinois, Indiana, Kentucky, Ohio, Pennsylvania, Tennessee and West Virginia.

The UMW has not publicly sanctioned the sympathy walkout and has urged wildcatters to go back to work.

The head of West Virginia's third-leading coal producer, frustrated that UMW officials won't answer his phone calls, says he blames the shutdown on the union.

''As far as I'm concerned, I'm for calling this contract null and void right now,'' said Paul Kiser, president of Beckley-based Maben Energy Corp. ''If the union can't live up to its agreement, what good is it?''

Danny Wells, a UMW district spokesman, said Maben Energy remains under contract until 1993.

''Companies haven't been living up to their contracts with the union, either,'' Wells said. ''But we still have an agreement. Mr. Kiser will find that pulling out of his contract will be easier said than done.''

The Pittston miners have concentrated on the company's withdrawal from a national contract to win work rule changes it says are necessary to meet competition from foreign producers.

The strike's focus has turned to health benefits in recent days, though. Pittston has refused to contribute to two health plans and two related retirement funds since its contract with the UMW expired in February 1988, court documents show.

The union and the UMW Health and Retirement Funds have filed lawsuits against the company. UMW spokesman John Duray estimates Pittston owes as much as $10 million to the UMW Health and Benefits Fund, a figure Pittston wouldn't confirm, the Charleston Daily Mail reported Thursday.

Documents show that the two health plans spent more money than they earned last year, and the Daily Mail said both funds continue to lose money.

Pittston lawyer John Wood contends Pittston had the right to pull out of the benefit plans when its UMW contract expired in February 1988.