September 3, 1985

The Khmer Rouge rebel movement in Cambodia announced today that its leader, Pol Pot, was retiring from command of the organization. The announcement on the Khmer Rouge radio said that Mr. Pol Pot, who ruled Cambodia for four years until Vietnam invaded the country in 1979, would assume a vaguely defined military advisory role. Diplomats and experts on the Khmer Rouge, whose rule of Cambodia was marked by a reign of terror and policies that left as many as two million people dead, reacted to the report with caution. They said it was unclear whether the announced change in leadership would be substantive.

The Economy President Reagan began his drive for income tax overhaul with a blunt attack on the current system in a campaign-style Labor Day speech. He said that his program would benefit middle-class and working-class families and that it was opposed by special interests. [Page A1.] Members of the tax-writing committees in Congress reported lackluster voter support for tax revision but said they would still work for sweeping changes. [D20.]

Prime Minister Margaret Thatcher announced a sweeping realignment of her Cabinet this evening in a what appeared to be a bold attempt to reverse a recent sharp decline in her political fortunes. With her Conservative Party in third place in the opinion polls and back-bench Tories in Parliament demanding a new initiative, Mrs. Thatcher carried out the most extensive shuffle of her six years in office. She installed new ministers in a third of the governmental departments, and chose a new party chairman - Norman Tebbit, a tough right-winger - to prepare for an election in 1987 or 1988. The major surprise of the shake-up, which had been predicted for months, was the demotion of Home Secretary Leon Brittan. From one of the so-called ''great offices of state,'' he was moved to the Department of Trade and Industry, where he replaces Mr. Tebbit. Mr. Brittan has been criticized as a poor communicator and may have damaged himself by his role in the suppression last month of a BBC television program on Northern Ireland.

When Henry Ford perfected the continuously moving assembly line around the turn of the century, he made mass production and a consumer society possible at the price of forcing factory workers to keep pace with machines. Now -compelled by increasing competition from abroad and concerned about outcries over American quality -major manufacturers are beginning to abandon this cornerstone of the industrial economy. Workers today are being retrained to handle the more thoughtful and complicated operations of the new manufacturing process. They are now permitted to stop what was once the unrelenting moving of parts in order to make sure that quality is maintained, and they are switching tasks among team members to alleviate the boredom of repetition. Robots, instead, are doing the types of tedious and unpleasant chores that Henry Ford's workers once sweated over. All this change is taking place in the pursuit of profit and manufacturing efficiency. But one unmistakable result is an increasing assault on the tyranny of the assembly line.

Junior Beeson was shot on a budding day this summer on a subway ride they used to call the ''Zoo Train.'' The car was crowded, an argument developed and someone pulled a gun. The detective on the case said the incident was ''spontaneous'' and that crime on New York's subways knows no particular zone or time of day. The old Zoo Train, which may be just as safe and just as dangerous as any other ride, is an emblem, as it were, for a system that has been troubled for decades. Starts From Eastchester The train, the IRT No. 5 express, begins its downtown run on the elevated tracks above Dyre Avenue in the Eastchester section of the Bronx, a worn but stable part of the borough near the Westchester County border.