More than 130 union supporters carrying bottles of champagne and noise makers crowded into two school buses and drove downtown yesterday afternoon to file their petition for a union election.

The enthusiastic supporters filled the seats and aisles of streamer-covered buses, passing song sheets, multi-colored buttons and plastic cups of champagne back and forth, while singing and congratulating each other.

"It's unreal. It's so wierd that this is actually happening, when we've waited for so long," said one support staff member, clipping a Harvard Union of Clerical and Technical Workers (HUCTW) button onto her lapel.

As they passed Holyoke Center, where the University's anti-union strategist Anne H. Taylor has her office, the buses slowed down long enough for the supporters to cheer, sing and wave fists out the window.

"We'll see how far the University goes to stop us," said one employee. "Whatever measures they take to stop us, we're going to get our union now."

When the buses arrived at the Thomas P. O'Neill Federal Building in downtown Boston, where the National Labor Relations Board (NLRB) has its regional headquarters, the workers walked into the building cheering, "When do we want? A union. When do we want it? Now."

"I thought this day might never come--it's thrilling," said a support staff member who has been organizing with the union since the mid-1970s.

The crowd gathered in the building's auditorium, and members of the NLRB spoke briefly, commenting that this was the largest group ever to accompany the filing of a petition for election.

HUCTW had originally planned to take only one busload of supporters to the NLRB, said Kris Rondeau, HUCTW director. But when employees' enthusiasm indicated that one bus would not carry everyone who wanted to go, the union hired a second bus yesterday morning.

"We've all just been waiting for this moment. Now the ball is rolling," said another employee. "It's the culmination of years of work."

"I am ecstatic," said Leslie Sullivan, who started the union organizing drive 17 years ago in the medical area but left the campaign in 1981. "I always knew it could be done."