Patent ID: 7422515

Claim:
A wide belt sander comprising: a base ( 10 ); a driving axle ( 20 ) rotatably mounted on the base ( 10 ) and having a central axis; a driving device mounted on the base ( 10 ) and connected to the driving axle ( 20 ); a driven axle bracket ( 30 ) rotatably mounted on the base ( 10 ) along a longitudinal axis perpendicular to the central axis of the driving axle ( 20 ); a driven axle ( 40 ) rotatably mounted on the driven axle bracket ( 30 ) along a rotating axis parallel with the central axis of the driving axle ( 20 ); a belt ( 60 ) endlessly mounted around the driving and driven axles ( 20 , 40 ); and an automatic adjustment device ( 70 ) mounted between the base ( 10 ) and the driven axle bracket ( 30 ) to drive the driven axle bracket ( 30 ) to swing relative to the base ( 10 ) along the longitudinal axis in a simple harmonic motion and comprising two cams ( 71 , 712 ) rotatably mounted on the base ( 10 ) at an interval and corresponding to the driven axle bracket ( 30 ); a pushed element ( 36 ) securely attached to the driven axle bracket ( 30 ) and mounted between and alternatively pushed by the cams ( 71 , 712 ) to swing the driven axle bracket ( 30 ) relative to the base ( 10 ); and a driving assembly mounted on the base ( 10 ) to drive the cams ( 71 , 712 ) to rotate.