A pulley (80, 80', 80") for a continuously variable transmission comprising: a shaft; a first sheave disposed on the shaft, the first sheave having a belt engaging surface; a second sheave disposed on the shaft, the second sheave having a belt engaging surface facing the belt engaging surface of the first sheave; a spring biasing the first sheave and the second sheave away from one another; a spider (90, 90') mounted on the shaft, the second sheave being disposed axially between the spider (90, 90') and the first sheave, the second sheave being axially moveable, the spider (90, 90') being axially fixed, the first sheave, the second sheave and the spider (90, 90') being adapted to rotate with the shaft; and a plurality of centrifugal weights connected to one of: the spider (90, 90'), and the second sheave, at least a portion of each of the plurality of centrifugal weights moving in a radially outward direction with respect to the shaft in response to rotation of the shaft, a radial position of the portion depending on a rotational speed of the shaft, the axial distance between the spider (90, 90') and the second sheave depending at least in part on the radial position of the portion, at least the portion of each of the plurality of centrifugal weights being adapted to move radially outwardly and thereby push the second sheave away from the spider (90, 90') and towards the first sheave at least in part in response to increasing rotational speed of the shaft; the pulley being characterized in that the pulley further comprises at least one cylinder (124, 144) adapted to receive fluid therein; and at least one piston (94, 94', 94"), the at least one piston (94, 94', 94") being moveable in the at least one cylinder (124, 144), the at least one piston (94, 94', 94") being adapted to move in response to the at least one cylinder (124, 144) receiving fluid therein, and being adapted to thereby selectively exert force on one of the first and second sheaves (82, 84) towards the other of the first and second sheaves (82, 84). a shaft; a first sheave disposed on the shaft, the first sheave having a belt engaging surface; a second sheave disposed on the shaft, the second sheave having a belt engaging surface facing the belt engaging surface of the first sheave; a spring biasing the first sheave and the second sheave away from one another; a spider (90, 90') mounted on the shaft, the second sheave being disposed axially between the spider (90, 90') and the first sheave, the second sheave being axially moveable, the spider (90, 90') being axially fixed, the first sheave, the second sheave and the spider (90, 90') being adapted to rotate with the shaft; and a plurality of centrifugal weights connected to one of: the spider (90, 90'), and the second sheave, at least a portion of each of the plurality of centrifugal weights moving in a radially outward direction with respect to the shaft in response to rotation of the shaft, a radial position of the portion depending on a rotational speed of the shaft, the axial distance between the spider (90, 90') and the second sheave depending at least in part on the radial position of the portion, at least the portion of each of the plurality of centrifugal weights being adapted to move radially outwardly and thereby push the second sheave away from the spider (90, 90') and towards the first sheave at least in part in response to increasing rotational speed of the shaft; the pulley being characterized in that the pulley further comprises at least one cylinder (124, 144) adapted to receive fluid therein; and at least one piston (94, 94', 94"), the at least one piston (94, 94', 94") being moveable in the at least one cylinder (124, 144), the at least one piston (94, 94', 94") being adapted to move in response to the at least one cylinder (124, 144) receiving fluid therein, and being adapted to thereby selectively exert force on one of the first and second sheaves (82, 84) towards the other of the first and second sheaves (82, 84). the spider (90, 90'), and the second sheave,