Actually, the original purpose of a filibuster is to prevent a vote on the bill. At some times, a group would get together and pass the speaker's role to each other, to allow some rest.. Other times an individual will speak for as long as he can before giving up.
the use of irregular or obstructive tactics by a member of a
legislative assembly to prevent the adoption of a measure generally
favored or to force a decision against the will of the majority
Filibuster in the United States Senate
A filibuster in the United States Senate is a dilatory or obstructive
tactic used in the United States Senate to prevent a measure from
being brought to a vote. The most common form of filibuster occurs
when a senator attempts to delay or entirely prevent a vote on a bill
by extending the debate on the measure, but other dilatory tactics
exist. The rules permit a senator, or a series of senators, to speak
for as long as they wish and on any topic they choose, unless
"three-fifths of the Senators duly chosen and sworn" (usually 60
out of 100 senators) bring debate to a close by invoking cloture under
Senate Rule XXII.
While many times a Senator will speak to an empty chamber, he can call for a quorum which forces senators to appear for roll call. Additionally, quorum calls themselves can be used to delay matters. Also if the opposition is present during a filibuster, they can vote down the bill before the actual majority of for votes make it to the floor.
The intended purpose of a quorum call is to establish the presence of
a constitutional quorum, but senators routinely use them to waste time
while waiting for the next speaker to come to the floor or for leaders
to negotiate off the floor. In those cases, a senator asks unanimous
consent to dispense with the quorum call. If a member objects, the
clerk must continue to call the roll of senators just as is done with
a vote. When a call shows no quorum, the minority can force another
vote by moving to request or compel the attendance of absent senators
As an example
During the 1930s, Senator Huey Long used the filibuster to promote his
populist policies. The Louisiana senator recited Shakespeare and read
out recipes for "pot-likkers" during his filibusters, one of which
occupied 15 hours of "debate".
One of the most notable filibusters of the 1960s occurred when
southern Democratic senators attempted to block the passage of the
Civil Rights Act of 1964 by making a filibuster that lasted for 75
hours, which included a 14-hour-and-13-minute address by Senator
Robert Byrd. The filibuster failed when the Senate invoked cloture for
only the second time since 1927.