Patent ID: 7175554

Claim:
Hydraulically controllable constant speed drive, comprising: an input shaft ( 10 ) provided with an input pulley ( 1 ), an output shaft ( 20 ) provided with an output pulley ( 2 ), and a drive belt ( 3 ), each of the input pulley ( 1 ) and the output pulley ( 2 ) provided with two pulley sheaves ( 11 , 12 ; 21 , 22 ), the two pulley sheaves of each pulley comprising a fixed sheave ( 11 , 21 ) and a displaceable sheave ( 12 , 22 ) axially displaceable, toward the fixed sheave ( 11 , 22 ), under the influence of a hydraulic pressure to be exerted in a piston-cylinder assembly ( 14 , 15 ; 24 , 25 ) associated with the pulley ( 1 , 2 ), each set of the fixed and displaceable sheaves defining a tapered groove of variable axial width wherein the drive belt ( 3 ) is accommodated, an input spring ( 17 ) bearing against the displaceable sheave ( 12 ) of the input pulley ( 1 ) that realizes an axial force urging the displaceable sheave ( 12 ) of the input pulley ( 1 ) towards the fixed sheave ( 12 ) of the input pulley ( 1 ), wherein, the drive is configured as an hydraulically controllable constant speed drive with the output shaft driven at a virtually constant rotational speed.