The Senate Commerce Committee took a major step yesterday toward passage of a trucking deregulation package, narrowly defeating a move to kill a provision that would lift the antitrust immunity allowing truckers to set rates jointly.

The committee rejected by a 9-to-8 vote a proposal by Sen. Ernest Hollings (D-S.C.) that would have eliminated the rate-making section from trucking package.

Although the committee did not pass the deregulation package, a final vote on the measure is expected Tuesday.

In addition to retaining the antitrust section, which stems from the 1948 Reed-Bulwinkle Act, the committee also defeated a proposal by Sen. Warren Magnuson, (D-Wash.), that would have retained the portion of the Interstate commerce Commission's mandate that forces new truck firms to show their entry into the marketplace would serve the public interest. f

The provisions of the bill considered yesterday require the ICC to grant entry unless such a move would be inconsistent with the public interest, thus reversing the standard and easing entry into the industry.

The bill under consideration was introduced by Sens. Howard Cannon (D-Nev.), the committee chairman, and Robert Packwood (R-Ore.), the ranking minority member.

The Cannon-Packwood proposal is a less sweeping version of another deregulation package introduced by the Carter administration, Sen. Edward Kennedy (D-Mass.) a leading trucking deregulation proponent -- and others.

The Carter administration has been urging Congress to act this year on trucking legislation. The votes yesterday signified a major victory for the administration and other deregulation advocates.

But the vote indicates that the committee, despite predictions to the contrary in recent months, is willing to take on the powerful industry. In fact, the antitrust immunity issue is the single question on which industry lobbyists appear least willing to compromise.

The antitrust part of the bill applies only to single-line rates, or rates involving single trucking companies rather than two firms offering joint rates. Hollings, who emerged as the bill's most outspoken opponent, said lifting the immunity would give large trucking firms "financial leverage to gut the entire system."

Cannon, on the other hand, strongly defended the ending of that part of the rate bureau system. "I can't for the life of me understand . . . giving them an antitrust immunity that we don't give to anyone else under comparable circumstances," Cannon said.

Cannon and Packwood did suffer a defeat when the committee voted to lift a section of the package dealing with owner-operators. That proposal would have effectively deregualted that sector of the industry.

In addition, the committee also voted to consider an expansion of the "zone of reasonableness" -- the range in which truckers could freely raise or lower their rates. Committee members agreed to a proposal that would allow rate increases to include a measurement of the inflation, rate, so that those rate hikes would take a truckers' costs into consideration.

Despite the results favorable to deregulation at the committee session, Hollings repeatedly cited decreasing air service to South Carolina, his home state, as evidence of the failures of airline deregulation. He appeared ready to push again Tuesday for maintaining much of the regulatory status quo.

Committee members said there would be a barrage of industry lobbying before their session next week in an effort to convince the nine members who voted for the immunity repeal to change their votes.

Transportation Secretary Neil Goldschmidt issued a statement after the session praising the legislation as "strong and effective" and saying the members had "successfully resisted efforts so far to water it down."

Several committee sources including Cannon, and Carter administration officials said that the nine votes in favor of the key antitrust provision were firm.