On a plane trip to Michigan to campaign for President Reagan in 1984, Commerce Secretary Malcolm Baldrige was obviously in pain. He had broken his right thumb the day before roping calves with friends in Virginia and he was unable to button his shirt cuffs or tear open the sugar package for his coffee.

But Mr. Baldrige, stoic and proud in the best tradition of a western cowboy, would not accept help or go to a doctor. Minor injuries were part of rodeo life, and Mr. Baldrige was going to play that role even though he was a member of the Cabinet. He had a nurse in the Commerce Department bandage the thumb, saying that it would heal in the same amount of time no matter whether he saw a doctor.

Mr. Baldrige, 64, died yesterday doing what he loved to do most -- roping calves rodeo-style. He maintained that hobby, picked up when he worked on a Nebraska ranch one summer when he was going to school, despite his eastern prep school education and a degree in English from Yale University.

He wore a big cowboy belt buckle, engraved with his nickname -- "Mac" -- with his favorite pin-striped double-breasted suits. And among the decorations in his office was a hand-tooled saddle that he won in rodeo competition.

He once saddled a Commerce Department secretary, with her permission, to show a group of visitors how it was done, and invited a reporter to a special rodeo at Capital Centre and a White House barbecue to teach him how real people live outside Washington.

He admired cowboys, he said, because "they don't talk unless they have something to say." And cowboys liked his down-to-earth manner that belied his position of a former corporate chief executive and a Cabinet secretary. Mr. Baldrige was named Professional Rodeo Man of the Year in 1980, before he joined the Reagan Cabinet, and was elected to the National Cowboy Hall of Fame in 1984.

Mr. Baldrige fought government bureaucratese, trying to force Commerce Department officials to write in straightforward English. He programmed word processors in his office to reject language that was not direct, but was not as successful with most of the 38,000 agency employes.

The toughness of the rodeo roper came through to his Cabinet position, as Mr. Baldrige became one of the most influential commerce secretaries in history, transferring what had been a second-tier Cabinet position into the mainstream of the Reagan administration's economic decision-making.

He battled within the Cabinet against what he saw as ideological free traders who had no idea how the real world worked. And after four years of frustration he saw many of the trade policies that he espoused adopted by the president.

He pushed for action to weaken the dollar because its high value hurt American businesses trying to sell abroad, and in 1985 Treasury Secretary James A. Baker III started a coordinated policy with Japan and Germany to bring the value of the dollar down. Similarly, he pressed for a tougher stance against unfair trade practices, which was adopted in 1985.

At the same time that he called for sanctions against trading partners such as Japan, Mr. Baldrige fought against business, labor unions and members of Congress who he thought wanted to steer the United States on a dangerously protectionist course. He warned 10 days ago that other nations were just waiting for the United States to turn protectionist so they could do the same. And he said growth in global trade barriers would be a major setback to the economies of the United States and the world.

Mr. Baldrige rose to corporate executive after starting on the shop floor. After graduating from Yale and after serving in the infantry in World War II, he took a job as a mill hand in a Cleveland foundry. He was promoted to superintendent, and often told of how he stopped a rash of sitdown strikes by going as far as he could to meet the workers' gripes, and then dumping molten metal on the foundry floor in a cloud of dust, smoke and broken glass when they tried one more work stoppage. He said that ended the strike because the men realized they could deal with him, but they had better not push him too far.

He moved from the shop floor to become president of Eastern Malleable Iron Co. of Naugatuck, Conn., in 1960. Two years later he joined Scovill Inc. of Waterbury, Conn., transforming it from a financially troubled brass mill into a diversified manufacturer of consumer, housing and industrial goods with 81 plants in the United States and 22 other countries.

While at Scovill, Mr. Baldrige became chairman of the Connecticut Bush for President Committee. When Reagan was nominated, he switched to become cochairman of Connecticut Reagan-Bush for President Committee. He remained close to the vice president and recently denied rumors that he planned to resign to work in the Bush campaign.

He transformed the Commerce Department from an agency concerned mainly with domestic industries to one that pressed the United States' global trade concerns. He said that among his greatest accomplishments was leading the fight -- against the opposition of the Pentagon and Defense Secretary Caspar W. Weinberger -- to ease restrictions on high-technology sales to China and India.