In a V-belt continuously variable transmission (CVT), a sheave drive
mechanism includes a movable tube coupled to a movable sheave half of a
primary sheave so as to be rotatable with respect thereto and axially
movable together therewith, a fixed tube disposed internally of and
coaxially with the movable tube, and a ball screw mechanism provided
between the fixed tube and the movable tube. The sheave drive mechanism
further includes an outer peripheral wall arranged to cover the area from
a fixed end of the fixed tube to the outer periphery of the movable tube,
an oil seal provided between the movable tube and the outer peripheral
wall to seal an internal space for enclosing the working surface of the
ball screw mechanism, and a communication path for communication between
the internal space and the outside of the outer peripheral wall. The
V-belt (CVT) has a smooth feed operation of the ball screw mechanism in
the sheave drive mechanism and has a high durability attained by
waterproofing.