Without actually saying so, three Supreme Court justices unexpectedly asked Congress yesterday to ease their swollen and still-growing work-load by creating a brand-new tribunal mainly to decide cases that the Supreme Court would spin off.

But Chief Justice Warren E. Burger and Justices Byron R. White and Harry A. Blackmun not only fell two signatures short of a majority, but elicited a brief, tart dissent from Justice William J. Brennan Jr.

He reminded his colleagues that he had told a commission formed to study the issue that he "remains completely unpersuaded... that there is any need for a new national court." That was in 1972, but, obviously, Brennan holds the same view today.

The court's most junior justice, John Paul Stevens, wasn't heard from yesterday. But he may have made a comment of sorts last July, when he reduced the number of his clerks from three to two. Most of the justices have four clerks.

More recently, Stevens pointedly said that the court shouldn't waste scarce time and energies writing dissents when it denies petitions for review of decisions by lower courts.

If yesterday's Supreme Court output was a clue, Stevens' advice isn't being taken by most of his eight colleagues.

White, joined by Blackmun, wrote a perfunctory two-page dissent to denial of review in a freight-rate case.

Justice William H. Rehnquist, joined by Justice Lewis F. Powell Jr., wrote an eight-page dissent to the court's refusal to hear two relatively minor school-desegregation cases.

Powell, joined by Blackmun, dissented, in five pages, to his colleagues' refusal to decide a personal-injury case.

Brennan, joined by Justice Thur-good Marshall, wrote a two-page dissent to a denial of review in a search-and-seizure case.

White, using his two-page freight-case dissent as a vehicle, wrote a nine-page essay on a proposed national court of appeals. A bill for such a court, he noted pointedly in his final sentence, "did not proceed beyond the hearing stage."

The gist of White's argument, bolstered by a brief description of two dozen meritorious cases that fell by the wayside at the start of the term in October, was this:

Forty years ago, the court was able to give full consideration to all the cases that deserved it. But then the number of new filings on the court docket was fewer than 1,000. It is about 4,000 today.

During the 24 years ending in 1970, the court annually decided an average of 101 cases a year with full opinions. Since then the court's average has climbed to 170 -- a total "we cannot hope substantially to exceed..."

Even by 1972, a study group headed by Havard Law professor Paul Freund said, the court's "staggering" workload was "incompatible with the appropriate fulfillment of its historic and essential functions."

Burger, in a seven-page supporting statement, said that Justices Blackmun, Powell and Rehnquist all share White's views "on the need for some relief if this court is to achieve and maintain the optinum level of quality in its work." And, he said, Justice Potter Stewart has said it is "likely that the day would come when a new court would be needed."