It's a little unusual for major political campaigns to switch campaign managers less then two months before the election, but that's what has happened in City Council member Arlington Dixon's organization. Barry Campbell is out, and Vivien Cunningham is in as the person responsible for day-to-day operations of Dixon's drive to become the council chairman.

The announced reason for Campbell's departure is also unusual. Dixon was getting concerned that the campaign had placed too much of a strain on the operations of his office at city hall, according to Cunningham. Not only had Campbell, his former executive assistant, left to run the campaign. But Bruce French, chief clerk of the government operations committee of which Dixon is chairman, had also left.

So, Cunningham said, Dixon decided that Campbell should go back to the District Building. "He wasn't asked to go. He was asked if he would go," Cunningham said. "We had two people who could be the campaign manager and one who could go to the City Council. If we're campaigning on efficiency in government, we couldn't allow the government operations committee to fall apart." Campbell returned to city hall this week to head up the committee staff.

The timing of his return is odd. There are only two weeks left before the Council takes a month-long summer recess. And less than two weeks after the recess ends, the all-important Sept. 12 Democratic primary will be over. If Dixon wins the primary, his chairmanship of the committee will have to be balanced with his preparation to assume the job of running the council. If he loses to his major rival in the election, council member Douglas E. Moore, some city hall sources say Dixon would probably be lucky to be named chairman of a standing committee on paper clips.

So why did Campbell go?

A primary reason, according t sources close to the campaign, was continuing differences between Campbell on the one hand and, on the other, Cunningham and Sharon Pratt Dixon, the candidate's wife. In the view of many political observers, Mrs. Dixon is her husband's chief political adviser.

"Either Barry had to go or Sharon had to go," one source said. "Barry didin't have much leverage in that situation."

The differences, according to sources, involved campaign strategy, location of campaign offices and Campbell's involvement in the decision-making process of the campaign. Shortly before his departure, there was disagreement over whether to locate a campaign office at 4228 Wisconsin Ave. NW. Campbell opposed that site.

Cunningham acknowledged that there were disagreements over the office site and other things, but, she said, "he actually didn't leave because he was opposed to the office." Campbell, who has been Dixon's executive assistant on the council since 1974 and was expected by many to run for Dixon's Ward 4 seat if his boss wins, will not talk about why he left.

The new campaign manager, Cunningham, was formerly the chairman of the campaign organization and was often designated as its principal spokesperson. Cunningham will remain co-chairman of the campaign, a title she will now share with Sharon Pratt Dixon.

The Washington, D.C. Area Trucking Association, which represents more than 150 truck-hauling firms in the metropolitan area, knows the right people in city government to invite to its monthly meetings.

Not only has the group invited all three of the major candidates for mayor to attend one of the luncheon meetings. But last week, when Mayor Walter E. Washington made his appearance, one of the guests at the head table was Capt. Wayne Layfield, who is in charge of the Traffic Enforcement Bureau of the D.C. Police Department.

That bureau is the liaison between the city government on such matters as traffic flow, parking and tickets. Tickets, often given for double parking when loading zones are otherwise occupied, are a major problem for association members, according to the group's executive vice-president, Roalia Furr.

There was no ticket fixing at this luncheon, however, even though the mayor, who outshined Layfield as the star of the show, jokingly made reference to it. "You park double, and the captain puts one on you. He told me he was going to reform," Washington said. "He made that promise before, and he couldn't keep it."

Washington lauded the group for its use of bumper stickers to promote the 55 mile-per-hour speed limit. But he also warned, "You've got a speed limit of 55, and I hope you don't use it on 16th Street, because then the captain will have to break another promise," he said.

"I know some of you have been approached by other candidates to see if they could engage your services in moving their offices (after the election)," the mayor said. "I want you to know that that's a losing business. The mayor doesn't plan on moving anywhere."

City Council member and council chairman candidate Douglas E. Moore claims to have scored a coup on his arch council rival, Marion Barry, last week by being the one to formally make the motion that the council pass legislation giving teachers, police and firefighters pay raises at the same time other city employes receive them.

The bill was sponsored by Barry, who himself scored a coup on Mayor Walter E. Washington last year by getting representatives of these groups to agree to pay raises equal to those of other city employes at a time when union negotiators were still hassling with the mayor's representatives.

When this year's legislation came up for a vote last week, however, Barry has stepped out of the council chambers. So Moore quickly spoke up and made the motion, much to Barry's mild chagrin. Barry said later that the unions will still know who their friends are and who did most of the work. But a gleeful Moore disagreed, saying the workers should now see that Barry is "not dependable.

"I'm always on the alert for my constituents' interests, and there are 17 teachers in my family. We're a teaching clan," Moore boasted.